text:
One Ring
From Wikipedia, the free encyclopedia
Jump to: navigation, search
"Ring-bearer" and "The One Ring" redirect here. For the attendant in a wedding ceremony, see Page boy (wedding attendant). For the role-playing game, see The One Ring Roleplaying Game.
This Middle-earth-related article describes a work or element of fiction in a primarily in-universe style. Please help rewrite it to explain the fiction more clearly and provide non-fictional perspective. (January 2017) (Learn how and when to remove this template message)
The One Ring
Artist's unofficial representation of the One Ring
Plot element from the Lord of the Rings franchise
First appearance
The Hobbit (1937)
Created by
J. R. R. Tolkien
Genre
Fantasy
In-story information
Type
Magical ring
Function
Invisibility
Control over other Rings of Power
Specific traits and abilities
Plain gold ring; glowing inscription appears when ring is placed in flames
Affiliation
Sauron
Isildur
Gollum
Bilbo Baggins
Frodo Baggins
Samwise Gamgee
Celebrimbor
The One Ring is an artefact that appears as the central plot element in J. R. R. Tolkien's The Lord of the Rings (1954–55). It is described in an earlier story, The Hobbit (1937), as a magic ring of invisibility. In the sequel, The Lord of the Rings, Tolkien ascribes to the Ring a darker character, with malevolent power going far beyond conferring invisibility: it was created by Sauron the Dark Lord as part of his design to win domination over Middle-earth. The Lord of the Rings concerns the quest to destroy the Ring to keep Sauron from fulfilling his design.
Contents
[hide]
1 Literature
1.1 Description
1.2 Appearance
1.2.1 Inscription
1.3 Ring-bearers
1.4 Internal history
1.5 Powers
1.6 Fate of the Ring-bearers
2 Symbolism
3 Adaptations
4 See also
5 Notes
6 References
Literature[edit]
In The Lord of the Rings and the posthumously published The Silmarillion, Tolkien provides a detailed internal development from the forging of the Ring to its destruction. In the fictional context of Middle-earth, these events take place during several thousand years in the Second and Third Age of Arda.
Description[edit]
The One Ring was forged by the Dark Lord Sauron during the Second Age to gain dominion over the free peoples of Middle-earth. In disguise as Annatar, or "Lord of Gifts", he aided the Elven smiths of Eregion and their leader Celebrimbor in the making of the Rings of Power. He then forged the One Ring himself in the fires of Mount Doom.[1]
Sauron intended it to be the most powerful of all Rings, able to rule and control those who wore the others. Since the other Rings were themselves powerful, Sauron was obliged to place much of his own power into the One to achieve his purpose.[2]
Creating the Ring simultaneously strengthened and weakened Sauron's power. On the one hand, as long as Sauron had the Ring, he could control the power of all the other Rings, and thus he was significantly more powerful after its creation than before;[3] and putting such a great portion of his own power into the Ring ensured Sauron's continued existence so long as the Ring existed. On the other hand, by binding his power within the Ring, Sauron became dependent on it—without it his power was significantly diminished.[1][3]
Appearance[edit]
The Ring seemed to be made simply of gold, but it was impervious to damage. It could be destroyed only by throwing it into the pit of the volcanic Mount Doom where it was originally forged. Unlike other rings, the One Ring was not susceptible to dragon fire.[4] Like some lesser rings forged by the Elves as "essays in the craft"—but unlike the other Rings of Power—the One Ring bore no gem. Its identity could be determined by a little-known but simple test: when placed in a fire, it displayed a fiery Tengwar inscription in the Black Speech of Mordor, with two lines from a rhyme of lore describing the Rings:
Three Rings for the Elven-kings under the sky,
Seven for the Dwarf-lords in their halls of stone,
Nine for Mortal Men doomed to die,
One for the Dark Lord on his dark throne
In the Land of Mordor where the Shadows lie.
One Ring to rule them all, One Ring to find them,
One Ring to bring them all and in the darkness bind them
In the Land of Mordor where the Shadows lie.
The lines inscribed on the Ring (in boldface above) were pronounced by Sauron when he forged the Ring. The Elven smiths heard him chanting them, and thereupon became aware of his purpose and took off their own Rings to foil his plan.
A person wearing the Ring would enter a shadowy world revealing the physical world from a different aspect, from which physical objects were harder to see. The wearer was mostly invisible to ordinary beings, such as Men, but highly visible to the Nazgûl. The Ring dimmed the wearer's sight, while at the same time sharpening the other senses.
The enigmatic Tom Bombadil appeared to be unaffected by the Ring and to have some power over it; when he wore the Ring, it did not make him invisible, and Frodo could not become invisible to him by wearing the Ring. Also, Tom played with the Ring like a conjurer borrowing someone's watch for a trick, seemingly making it disappear and reappear.
The Ring slowly but inevitably corrupted its bearer, regardless of the bearer's initial intent. For this reason the Wise, including Gandalf, Elrond, and Galadriel, refused to wield it themselves, but determined instead that it should be destroyed. The corrupting power of the ring was apparently stronger on individuals more inclined to evil and selfishness: it took almost immediate hold of the greedy Sméagol as soon as he saw it, and corrupted Boromir after a few months of near proximity, while its effects were only starting to be seen in the well-meaning Bilbo after his sixty years' possession.
The Ring had the ability to change size. As well as adapting to fingers of varying size, from Sauron's to Frodo's, it sometimes suddenly expanded to escape from its wearer.[5]
Inscription[edit]
The words of the ring-inscription are in Black Speech, a language devised by Sauron and used in the land of Mordor. The inscription reflects the One Ring's power to control the other Rings of Power. The writing uses Elvish letters (tengwar), in a mode (i.e. orthography) adapted to the Black Speech.
Normally the One Ring appeared perfectly plain and featureless, but when heated its inscription appeared in fiery letters. A drawing of the inscription and a translation provided by Gandalf appears in Book I, Chapter 2 of The Fellowship of the Ring, "The Shadow of the Past".
Gandalf speaks the words in Black Speech in Book II, Chapter 2, "The Council of Elrond":
Ash nazg durbatulûk, ash nazg gimbatul,
Ash nazg thrakatulûk agh burzum-ishi krimpatul.
Translated, the words mean:
One ring to rule them all, one ring to find them,
One ring to bring them all and in the darkness bind them.
When Isildur took the Ring from Sauron's hand, it was burning hot, so the letters were legible. Isildur was able to transcribe the inscription before it faded as the Ring cooled. This transcription survived in a document Isildur left in Gondor before marching north to the Gladden Fields, where he was killed and the Ring lost.
Gandalf learned of the Ring's inscription when he read Isildur's account. When Gandalf subsequently heated the ring that Bilbo Baggins had left to Frodo, the inscription reappeared. The wizard then had no doubt that Frodo's ring was the One Ring. When Gandalf recited the inscription in Black Speech at the Council of Elrond, everyone trembled:
The change in the wizard's voice was astounding. Suddenly it became menacing, powerful, harsh as stone. A shadow seemed to pass over the high sun, and the porch for a moment grew dark. All trembled, and the Elves stopped their ears.
The first Ballantine paperback edition of The Fellowship of the Ring printed the inscription upside-down. Some recent editions[6] accidentally omit the first half of the translation in Book I, Chapter 2. This error was corrected in the 50th Anniversary edition.
Ring-bearers[edit]
The term Ring-bearer is used in The Lord of the Rings to describe a person who has possessed the One Ring. The term is also used to refer to bearers of other Rings of Power.
In The Lord of the Rings, Frodo Baggins was appointed Ring-bearer by the Council of Elrond in Rivendell. His task was to carry the One Ring from Rivendell to the Crack of Doom in Mordor and to destroy it before Sauron or his servants could recover it. During this journey, Frodo's companion Samwise Gamgee also carried the ring briefly while Frodo was held captive in the Tower of Cirith Ungol. Near the onset of this journey the Ring was handled also by Tom Bombadil, upon whom the Ring had no apparent effect, and by Gandalf, who cast it into Frodo's fireplace to verify that it was the One Ring.
Frodo inherited the Ring from his uncle Bilbo Baggins. In Tolkien's earlier novel, The Hobbit, Bilbo found the Ring in the caverns beneath the Misty Mountains. It had been lost in the caverns by Gollum, who used the invisibility it conferred to hunt orcs to eat. Gollum, a hobbit previously known as Sméagol, had kept the Ring for hundreds of years. He had murdered his friend Déagol to get the Ring shortly after Déagol found it in the river Anduin. Many centuries earlier the Ring had betrayed Isildur and fallen from his finger into the Anduin as he was eluding orcs—who killed him when he became visible. Isildur in turn had cut the Ring from the hand of Sauron, who had made the Ring and let much of his power flow into it. Sauron was the Ring's true master, and the only being who could bend it completely to his will.
Though Déagol and Gandalf had handled the Ring, the only individuals ever to wear it were Sauron, Isildur, Sméagol/Gollum, Bilbo, Frodo, Tom Bombadil, and Samwise. None but Bilbo, Frodo, and Samwise are actually called "Ring-bearers" in any of Tolkien's works. As Ring-bearers, they were granted passage to the Undying Lands, though Sam lived in the Shire for many years after the departure of Bilbo and Frodo before making the journey himself.
Internal history[edit]
Further information: Timeline of Arda
After its original forging (about S.A. 1600) Sauron waged the War of the Elves and Sauron against the Elves and all who opposed him. Sauron invaded and destroyed Eregion, and killed Celebrimbor, the maker of the three rings of the Elves. However, King Tar-Minastir of Númenor sent a great fleet to Middle-earth, and with this aid Gil-galad destroyed Sauron's army and forced Sauron to return to Mordor.
In S.A. 3261, Ar-Pharazôn, the last and most powerful king of Númenor, landed at Umbar at the head of an immense army to do battle with Sauron. The sheer size and might of the Númenórean army was enough to force Sauron's armies to flee. Sauron surrendered to Ar-Pharazôn and was taken back to Númenor as a prisoner. Tolkien, in a letter written in 1958 (#211) wrote that the surrender was both "voluntary and cunning" so he could gain access to Númenor. Sauron was able to use the Númenóreans' fear of death as a way to turn them against the Valar, and manipulate them into worshipping his master, Morgoth, and performing human sacrifice.
Although Sauron's body was destroyed in the Fall of Númenor, his spirit was able to travel back to Middle-earth and wield the One Ring in his renewed war against the Last Alliance of Elves and Men between S.A. 3429 and 3441. Tolkien emphasized that Sauron used his ring in Númenor to gain complete control over its people; and while Sauron's body perished in the Fall, the Ring somehow made it back to Middle-earth. Tolkien wrote, "I do not think one need boggle at this spirit carrying off the One Ring, upon which his power of dominating minds now largely depended." (letter #211).
Sauron was killed again by Gil-galad and Elendil at the end of the Last Alliance. The Ring was cut from Sauron's hand by Elendil's son, Isildur, on the slopes of Mount Doom. Though counselled to destroy the Ring, he was swayed by its power and kept it safe instead, "as weregild for my father, and my brother". A few years later, Isildur was ambushed by orcs by the River Anduin near the Gladden Fields; he put on the Ring to escape, but it slipped from his finger as he swam across the river, and, suddenly visible, he was killed by the orcs. Since the Ring indirectly caused Isildur's death, it was known in Gondorian lore as "Isildur's Bane".
The Ring remained hidden on the river bed for almost two and a half millennia, until it was discovered on a fishing trip by a Stoor hobbit named Déagol. His friend and relative Sméagol, who had gone fishing with him, was immediately ensnared by the Ring's power and demanded that Déagol give it to him as a "birthday present"; when Déagol refused, Sméagol strangled him and took it for himself. The Ring corrupted his body and mind, turning him into the creature known as Gollum. The Ring, which Sauron had endowed with a will of its own, manipulated Gollum into hiding in a cave under the Misty Mountains near Mirkwood, where Sauron was beginning to resurface. There Gollum remained for nearly 500 years, until the Ring tired of him and fell off his finger as he was hunting an orc.
As is told in The Hobbit, Bilbo found the Ring shortly afterward while lost in the tunnels near Gollum's lair. When The Hobbit was written, Tolkien had not yet conceived of the Ring's sinister history. Thus, in the first edition of The Hobbit, Gollum surrenders the Ring to Bilbo as a reward for winning the Riddle Game. When Tolkien revised the nature of the Ring for The Lord of the Rings, he realized that the Ring's grip on Gollum would never permit him to give it up willingly. Tolkien therefore revised the second edition of The Hobbit: after losing the Riddle Game to Bilbo, Gollum went to get his "Precious" (as he always called it) so he could kill and eat Bilbo, but flew into a rage when he found the Ring missing. Deducing from Bilbo's last question—"What have I got in my pocket?"—that Bilbo had found the Ring, Gollum chased him through the caves, not realizing that the hobbit had discovered the Ring's powers of invisibility and was following him to the cave's exit. Bilbo escaped Gollum and the goblins by remaining invisible, but when he rejoined Gandalf and the dwarves he was travelling with, he decided not to tell them that the Ring had made him invisible. In fact he told them a story that closely followed the first edition of The Hobbit: that Gollum had given him the Ring and showed him the way out. Gandalf was not convinced and later forced the real story from Bilbo; he was thus immediately suspicious of the Ring.
Gollum eventually left the Misty Mountains to track down and reclaim the Ring. He wandered for decades, and was drawn to Mordor, where he was captured by Sauron's forces. He was interrogated by Sauron himself, who learned that the Ring had been found and was currently held by one "Baggins" in the land of "Shire".
In T.A. 3001, the Ring was beginning to strain Bilbo, leaving him feeling "stretched-out and thin", and so he decided to leave the Shire, intending to pass the Ring to his adopted heir Frodo Baggins. He briefly gave in to the Ring's power, even calling it "my precious"; alarmed, Gandalf spoke harshly to his old friend to persuade him to give it up, which Bilbo eventually did, becoming the first Ringbearer to surrender it willingly.
By this time Sauron had regained much of his power, and the Dark Tower in Mordor had been rebuilt. Gollum, released from Mordor, was captured by Gandalf and Aragorn, and from him Gandalf learned that Sauron now knew where to find the Ring. To prevent Sauron from reclaiming his Ring, Frodo and eight other companions set out from Rivendell for Mordor in an attempt to destroy the Ring in the fires of Mount Doom. During the quest, Frodo gradually became more and more susceptible to the Ring's power, and feared that it was going to corrupt him. When he and his faithful companion Samwise Gamgee discovered Gollum on their trail and "tamed" him into guiding them to Mordor, Frodo began to feel a strange bond with the wretched, treacherous creature, while Gollum warmed to Frodo's kindness and made at least some effort to keep his promise. Gollum eventually gave in to the Ring's temptation, however, and betrayed them to the spider Shelob. Believing Frodo to be dead, Sam bore the Ring himself for a short time and experienced the temptation it induced; he wore it briefly twice, but never succumbed to it.
Sam rescued Frodo from a band of orcs at the Tower of Cirith Ungol. The hobbits, followed by Gollum, eventually arrived at Mount Doom, where Frodo was overcome by the Ring's power and claimed it for himself. At that moment, however, Gollum attacked him and bit off his finger, taking back the Ring. Gollum was too close to the edge: as he gloated over his prize he fell into the fires of Mount Doom, taking the Ring with him, thus destroying it and Sauron's power.
Powers[edit]
The Ring's primary power was control of the other Rings of Power and domination of the wills of their users.[7] The Ring also conferred power to dominate the wills of other beings whether they were wearing Rings or not—but only in proportion to the user's native capacity. In the same way, it amplified any inherent power its owner possessed.[7]
A mortal wearing the Ring became effectively invisible except to those able to perceive the non-physical world, with only a thin, shaky shadow discernible in the brightest sunlight.[7] The Ring would also extend the life of a mortal possessor indefinitely by preventing natural aging. Gandalf explained that it does not "grant new life", but that the possessor merely "continues" until life becomes unbearably wearisome. However, the Ring could not protect its bearer from destruction; Gollum perished in the Crack of Doom while in possession of the Ring, and even Sauron himself could not preserve his body from destruction during the downfall of Númenor. Likewise, the Ring could not protect its bearer from physical harm; Frodo was seriously injured by the Witch-king on Weathertop, and lost a finger when Gollum bit it off—on both occasions while wearing the Ring. Sauron himself suffered the death of his physical body at the hands of Gil-galad and Elendil while wearing the Ring. Like the Nine Rings, the One Ring could physically corrupt mortals who wear it for extended periods of time, eventually transforming them into wraiths. Hobbits were more resistant to this process than Men: Gollum, who possessed the ring for five-hundred years did not become wraith-like because he did not wear the ring often after taking it to the tunnels of the Misty Mountains.[8]
The Ring might also have given its wielder the ability to read minds, as Galadriel suggested to Frodo when he wondered why he could not read the thoughts of others as she did.
Within the land of Mordor where it was forged, the Ring's power increased so significantly that even without wearing it the bearer could draw upon it, and could acquire an aura of terrible power. When Sam encountered an orc in the Tower of Cirith Ungol while holding the Ring, he appeared to the orc as a powerful warrior cloaked in shadow "[holding] some nameless menace of power and doom." The orc was so terrified that it fled. Similarly at Mount Doom, when Frodo and Sam were attacked by Gollum, Frodo grabbed the Ring and appeared as "a figure robed in white... [that] held a wheel of fire." Frodo told Gollum "in a commanding voice" that "If you touch me ever again, you shall be cast yourself into the Fire of Doom," a statement fulfilled when Gollum fell into Mount Doom with the Ring. Although the Ring was certainly invoked with this statement, it is unclear whether Frodo was prophesying (Frodo had previously seen less sinister visions while in possession of the Ring), or if Frodo was actively laying a curse upon Gollum.
As the Ring contained a large part of Sauron's power, it was endowed with a malevolent sentience of sorts. While separated from Sauron, the Ring would strive to return to him by manipulating its bearer to claim ownership of it, or by abandoning the bearer at an opportune moment.[9] For example, it slipped from Isildur's finger during the ambush at Gladden Fields; moments later he was killed by orcs, leaving the Ring's whereabouts unknown to Sauron's enemies. It also slipped off Gollum's finger when the time was right for it to be brought back into the world at large. Warned by Bilbo of the Ring's tendency to slip off, Frodo carried the Ring on a chain.
To master all of the Ring's capabilities, a Ring wielder would need a disciplined and well-trained mind, a strong will, and great native power. Those with weaker minds, such as Hobbits and lesser Men, would gain little benefit from the Ring, let alone realize its full potential. Even for someone with the necessary strength, it would have taken time to master the Ring's power to the point where he was strong enough to overthrow Sauron.[9] The prospect of mastery is the main appeal that the Ring holds for those who come in contact with it. The Ring appears as a symbol of hope, offering the power to defeat Sauron and bring peace to the world. Yet in the end, its inherent malevolence would twist its bearer into another Dark Lord as evil as Sauron, regardless of one's intentions at the outset.
Despite its power, the Ring did not render its bearer omnipotent. Three times Sauron suffered military defeat while bearing the Ring, first by Gil-galad in the War of Sauron and the Elves, again by Ar-Pharazôn when Númenórean power so overawed his armies that they deserted him, and again at the end of the Second Age with his personal defeat by Gil-galad and Elendil. Tolkien indicates, however, that such a defeat would not have been possible in the waning years of the Third Age, when the strength of the free peoples was greatly diminished. There were no remaining heroes of the stature of Gil-galad, Elendil, or Isildur; the strength of the Elves was fading and they were departing to the Blessed Realm; the Dwarves had been driven out of Moria and would have been unwilling to concentrate their strength in any event; and the Númenórean kingdoms had either declined or been destroyed, and had few allies.
Fate of the Ring-bearers[edit]
Of the several bearers of the One Ring, three were still alive following the Ring's destruction, the hobbits Bilbo Baggins, Frodo Baggins, and Samwise Gamgee. Bilbo, having borne the Ring longest of the three, had reached a very advanced age for a hobbit. Frodo suffered both physical and psychological scars from his strenuous quest to destroy the Ring. Samwise, having only briefly kept the Ring, was affected the least and simply carried on a normal life following the Ring's destruction.
In consideration of the trials the Ring-bearers had endured, special dispensation was granted them by the Valar to travel to the Undying Lands, where it was hoped they could find rest and healing. At the close of The Return of the King, Bilbo and Frodo embark for the voyage to the West along with Galadriel, Elrond, and many of their folk, as well as Gandalf. Near the end of his life, Samwise is also said to have been taken to the Undying Lands, after living in the Shire for many years and raising a large family.
Tolkien emphasized that the restorative sojourn of the Ring-bearers in the Undying Lands would not have been permanent. As mortals, subject to the Gift of Men, they would eventually die and leave the world of Eä.[10]
Symbolism[edit]
Tolkien wrote the following about the idea behind the One Ring: "I should say that it was a mythical way of representing the truth that potency (or perhaps potentiality) if it is to be exercised, and produce results, has to be externalized and so as it were passes, to a greater or lesser degree, out of one's direct control." (Letter #211, 1958).
Tolkien always strongly held that The Lord of the Rings was not allegorical, particularly in reference to political events of his time such as World War II or the Cold War. At the same time he conceded "applicability" as being within the "freedom" of the reader,[11] and indeed many people have been inclined to view the One Ring as a symbol or metaphor. The notion of a power too great for humans to safely possess is an evocative one, and already in the 1930s there were technologies available to suggest the idea. By the time the work was published, though not when most of it was written, the existence of nuclear power and nuclear weapons were common knowledge, and the Ring was often taken as symbolic of them.[12] The effect of the Ring and its physical and spiritual after-effects on Bilbo and Frodo are obsessions that have been compared with drug addiction; actor Andy Serkis who played Gollum in the film trilogy cited drug addiction as an inspiration for his performance.[13]
Parallels have been drawn between the literary device of Tolkien's Cursed Ring and the titular ring in Richard Wagner's Der Ring des Nibelungen.[14] Tolkien dismissed critics' direct comparisons to Wagner, telling his publisher, "Both rings were round, and there the resemblance ceases."[15] According to Humphrey Carpenter's biography of Tolkien, the author held Wagner's interpretation of the relevant Germanic myths in contempt.[16] In the contrary sense, some critics hold that Tolkien's work borrows so liberally from Wagner that Tolkien's work exists in the shadow of Wagner's.[14] Others, such as Tom Shippey[17] and Gloriana St. Clair,[18] attribute the resemblances to the fact that Tolkien and Wagner have created homologue works based in the same sources. However, Shippey and other researchers have written on an intermediary position, stating that both the authors, indeed, used the same source materials but that Tolkien was, in fact, indebted to some of the original developments, insights and artistic uses made upon those sources that first appeared in Wagner, and sought to improve upon them.[19][20]
Adaptations[edit]
The One Ring in Peter Jackson's films.
In the 1981 BBC Radio serial of The Lord of the Rings, the Nazgûl chant the Ring-inscription.
In The Lord of the Rings film trilogy, the wearer of the Ring is always portrayed as moving through a shadowy realm where everything is distorted. In the book, neither Bilbo Baggins nor Frodo Baggins ever mentioned anything about this while using the Ring, but when Sam puts on the Ring at the end of The Two Towers he does experience something similar to this. Sam never wore the Ring on screen in Jackson's films. The actual Ring for the movies was designed and created by Jens Hansen Gold & Silversmith in Nelson, New Zealand, and was based on a simple wedding ring.
See also[edit]
Middle-earth portal
Ring of Gyges
Ring of the Nibelung
Notes[edit]
^ Jump up to: a b Tolkien, J. R. R. (1954), The Fellowship of the Ring, The Lord of the Rings, Boston: Houghton Mifflin (published 1987), "The Shadow of the Past", ISBN 0-395-08254-4
Jump up ^ Tolkien, J. R. R. (1977), Christopher Tolkien, ed., The Silmarillion, Boston: Houghton Mifflin, "Of the Rings of Power and the Third Age", p. 287–288, ISBN 0-395-25730-1
^ Jump up to: a b Carpenter, Humphrey, ed. (1981), The Letters of J. R. R. Tolkien, Boston: Houghton Mifflin, "Letter 131", p. 153, ISBN 0-395-31555-7
Jump up ^ J.R.R. Tolkien, The Lord of the Rings, "The Shadow of the Past", p. 61 (Houghton Mifflin, 50th Anniversary Edition, Boston & New York, 2004).
Jump up ^ J R R Tolkien: The Lord of the Rings. George Allen & Unwin, London, 1968. ISBN 0-04-823087-1. Page 60.
Jump up ^ For example, The Fellowship of the Ring, ISBN 0-618-00222-7, from the Houghton-Mifflin boxed paperback set of 1999.
^ Jump up to: a b c Carpenter 1981, #131 pg 152
Jump up ^ Tolkien, J.R.R. The Lord of the Rings. p. 57.
^ Jump up to: a b Carpenter 1981, #246 pg 332
Jump up ^ Letters, Number 246, p. 328.
Jump up ^ Carpenter 1981, #203
Jump up ^ Carpenter 1981, #226
Jump up ^ "Andy Serkis BBC interview". BBC News. March 21, 2003. Retrieved January 6, 2010
^ Jump up to: a b Alex Ross, "The Ring and the Rings> Wagner vs Tolkien", The New Yorker, December 22, 2003
Jump up ^ Carpenter 1981, #229
Jump up ^ Carpenter, Humphrey (1977), Tolkien: A Biography, New York: Ballantine Books, ISBN 0-04-928037-6
Jump up ^ Tom Shippey, The Road to Middle-earth, page 296
Jump up ^ "CMU Libraries: Book: Tolkien's Cauldron". Shelf1.library.cmu.edu. 2001-10-11. Retrieved 2011-11-16.
Jump up ^ "Project MUSE - Tolkien Studies - Roots and Branches: Selected Papers on Tolkien (review)". Muse.jhu.edu. Retrieved 2011-11-16.
Jump up ^ Roots and Branches
References[edit]
Carpenter, Humphrey, ed. (1981), The Letters of J. R. R. Tolkien, Boston: Houghton Mifflin, ISBN 0-395-31555-7
[hide]
v
t
e
J. R. R. Tolkien's legendarium
Writings
Principal works
The Silmarillion
The Hobbit
The Lord of the Rings
The Fellowship of the Ring
The Two Towers
The Return of the King
Other works
The Adventures of Tom Bombadil
The Road Goes Ever On
Posthumous publications
Unfinished Tales
The Letters of J. R. R. Tolkien
The History of Middle-earth (12 volumes)
Bilbo's Last Song
The Children of Húrin
The History of The Hobbit
The Tale of Beren and Lúthien
Fictional universe
Characters
Peoples
Individual Dwarves
Individual Elves
Individual Hobbits
Hobbit families
Individual Númenóreans
Individual Orcs
Kings of Arnor
House of Isildur
Rangers of the North
Arvedui
Aragorn
Eldarion
Kings of Dale
Kings of Gondor
House of Anárion
Eärnil II
Kings of Rohan
Éomer
Théoden
Rulers of Númenor
Realms
Objects
Rings of Power
One Ring
Three Rings
Palantír
Silmarils
Mithril
Weapons and armour
Sting
Concepts
Cosmology
Ages or timeline
Animals
Plants
Food and drink
Wars and battles
Rivers
Anduin
Roads
Languages
Magic
Hobbit Day
Secondary works and legacy
The Atlas of Middle-earth
The Complete Guide to Middle-earth
A Guide to Middle-earth
The Individuated Hobbit
J. R. R. Tolkien: Author of the Century
J.R.R. Tolkien Encyclopedia
Journeys of Frodo
The Lord of the Rings: A Reader's Companion
Images of Middle-Earth
Related fiction
Things named after Tolkien and his works
Tolkien's Ring
Tolkien: A Look Behind "The Lord of the Rings"
Retrieved from "https://en.wikipedia.org/w/index.php?title=One_Ring&oldid=814223528"
Categories:
Fictional elements introduced in 1937
Magic objects
Middle-earth rings and jewels
Fictional gemstones and jewelry
Hidden categories:
Articles with inconsistent citation formats
Use dmy dates from October 2015
Articles that need to differentiate between fact and fiction from January 2017
All articles that need to differentiate between fact and fiction
Tolkien articles that need to differentiate between fact and fiction
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Create account
Log in
Namespaces
Article
Talk
Variants
Views
Read
Edit
View history
More
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Wikipedia store
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact page
Tools
What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Wikidata item
Cite this page
Print/export
Create a book
Download as PDF
Printable version
In other projects
Wikimedia Commons
Languages
Aragonés
Беларуская
Беларуская (тарашкевіца)
Català
Čeština
Dansk
Deutsch
Eesti
Español
Euskara
فارسی
Français
Galego
한국어
Հայերեն
Hrvatski
Interlingua
Italiano
ქართული
Latina
Magyar
Nederlands
日本語
Norsk
Polski
Português
Română
Русский
Scots
Slovenščina
Српски / srpski
Suomi
Svenska
ไทย
Türkçe
Українська
Zazaki
中文
Edit links
This page was last edited on 7 December 2017, at 15:09.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
Privacy policy
About Wikipedia
Disclaimers
Contact Wikipedia
Developers
Cookie statement
Mobile view
Enable previews

value: mw-page-base noprint

value: mw-head-base noprint

value: firstHeading firstHeading en

value: siteSub noprint

value: jump-to-nav mw-jump

attr: role class

value:
note
hatnote navigation-not-searchable

tag: td

value: Wikipedia:Manual of Style/Writing about fiction

tag: b

attr: class href

tag: span

tag: small

value: plainlinks metadata ambox ambox-content ambox-in-universe

value: text-align:center;font-size:125%;font-weight:bold;background: #DAA520; color: #000000;

value:
/wiki/Lord_of_the_Rings
mw-redirect
Lord of the Rings

value: text-align:center;background: #DAA520; color: #000000;

value:
/wiki/Artifact_(fantasy)
mw-redirect
Artifact (fantasy)

value:
/wiki/Ages_of_Middle-earth
mw-redirect
Ages of Middle-earth

value:
/wiki/Seven_Rings
mw-redirect
Seven Rings

value:
/wiki/Disaster_of_the_Gladden_Fields
mw-redirect
Disaster of the Gladden Fields

value:
/wiki/Council_of_Elrond
mw-redirect
Council of Elrond

value:
/wiki/Cirith_Ungol
mw-redirect
Cirith Ungol

value:
/wiki/Undying_Lands
mw-redirect
Undying Lands

value:
/wiki/War_of_the_Elves_and_Sauron
mw-redirect
War of the Elves and Sauron

value:
/wiki/Last_Alliance_of_Elves_and_Men
mw-redirect
Last Alliance of Elves and Men

value:
/wiki/Men_(Middle-earth)
mw-redirect
Men (Middle-earth)

value:
/wiki/Drug_addiction
mw-redirect
Drug addiction

value: The Lord of the Rings (1981 radio series)

value: display:table-cell;padding:0.2em 0.2em 0.2em 0.3em;vertical-align:middle

value: margin:0.5em 0 0.5em 1em;border:solid #aaa 1px

value:
/wiki/Ring_of_the_Nibelung
mw-redirect
Ring of the Nibelung

value:
/wiki/Tolkien,_J._R._R.
mw-redirect
Tolkien, J. R. R.

value:
/wiki/Houghton_Mifflin
mw-redirect
Houghton Mifflin

value: -moz-column-width: 30em; -webkit-column-width: 30em; column-width: 30em; list-style-type: decimal;

value:
/wiki/List_of_Middle-earth_Dwarves
mw-redirect
List of Middle-earth Dwarves

value:
/wiki/List_of_Hobbits
mw-redirect
List of Hobbits

value:
/wiki/List_of_Middle-earth_Orcs
mw-redirect
List of Middle-earth Orcs

value:
/wiki/List_of_Middle-earth_objects
mw-redirect
List of Middle-earth objects

value:
/wiki/List_of_Middle-earth_animals
mw-redirect
List of Middle-earth animals

value:
/wiki/List_of_Middle-earth_plants
mw-redirect
List of Middle-earth plants

value:
/wiki/List_of_Middle-earth_roads
mw-redirect
List of Middle-earth roads

value: Languages constructed by J. R. R. Tolkien

value: The Lord of the Rings: A Reader's Companion

value: List of things named after J. R. R. Tolkien and his works

value: nowraplinks collapsible autocollapse navbox-inner

value: Category:Fictional elements introduced in 1937

value: Category:Fictional gemstones and jewelry

value: Category:Articles with inconsistent citation formats

value: Category:Use dmy dates from October 2015

value: Category:Articles that need to differentiate between fact and fiction from January 2017

value: Category:All articles that need to differentiate between fact and fiction

value: Category:Tolkien articles that need to differentiate between fact and fiction

value: Discussion about edits from this IP address [ctrl-alt-n]

value: A list of edits made from this IP address [ctrl-alt-y]

value: You are encouraged to create an account and log in; however, it is not mandatory

value: You're encouraged to log in; however, it's not mandatory. [ctrl-alt-o]

value:
/wiki/One_Ring
View the content page [ctrl-alt-c]
c

value: Discussion about the content page [ctrl-alt-t]

value: p-namespaces navigation vectorTabs p-namespaces-label

value:
p-variants
navigation
vectorMenu emptyPortlet
p-variants-label

value:
/w/index.php?title=One_Ring&action=edit
Edit this page [ctrl-alt-e]
e

value: Past revisions of this page [ctrl-alt-h]

value: p-views navigation vectorTabs p-views-label

value:
p-cactions
navigation
vectorMenu emptyPortlet
p-cactions-label

value:
mw-wiki-logo
/wiki/Main_Page
Visit the main page

value:
/wiki/Main_Page
Visit the main page [ctrl-alt-z]
z

value: Featured content – the best of Wikipedia

value: Find background information on current events

value:
/wiki/Special:Random
Load a random article [ctrl-alt-x]
x

value: portal navigation p-navigation p-navigation-label

value: Guidance on how to use and edit Wikipedia

value: About the project, what you can do, where to find things

value: A list of recent changes in the wiki [ctrl-alt-r]

value: portal navigation p-interaction p-interaction-label

value: List of all English Wikipedia pages containing links to this page [ctrl-alt-j]

value: Recent changes in pages linked from this page [ctrl-alt-k]

value:
/wiki/Wikipedia:File_Upload_Wizard
Upload files [ctrl-alt-u]
u

value: A list of all special pages [ctrl-alt-q]

value: Permanent link to this revision of the page

value: Link to connected data repository item [ctrl-alt-g]

value: Printable version of this page [ctrl-alt-p]

value: Пярсцёнак Усеўладдзя – Belarusian

value: Пярсьцёнак Усеўладзьдзя – Belarusian (Taraškievica orthography)

value: حلقه یگانه – Persian

value: Համիշխանության մատանի – Armenian

value: interlanguage-link interwiki-it badge-Q17437798 badge-goodarticle

value: ერთი ბეჭედი – Georgian

value:
https://nl.wikipedia.org/wiki/Ene_Ring
Ene Ring – Dutch
nl
nl
interlanguage-link-target

value:
https://ro.wikipedia.org/wiki/Inelul
Inelul – Romanian
ro
ro
interlanguage-link-target

value: Кольцо Всевластья – Russian

value:
https://sco.wikipedia.org/wiki/Ane_Ring
Ane Ring – Scots
sco
sco
interlanguage-link-target

value: Јединствени прстен – Serbian

value: เอกธำมรงค์ – Thai

value: Перстень Влади – Ukrainian

value: mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-One_Ring rootpage-One_Ring skin-vector action-view


text:
pH
From Wikipedia, the free encyclopedia
Jump to: navigation, search
For other uses, see PH (disambiguation).
pH values of some common substances
Acids and bases
pH
Reaction
Titration
Extraction
Dissociation constant (acid)
Acid strength
Acidity function
Buffer solutions
Proton affinity
Self-ionization of water
Amphoterism
Acid types
Brønsted
Lewis
Mineral
Organic
Strong
Superacids
Weak
Monobasic acid
Dibasic acid
Tribasic acid
Solid
Base types
Brønsted
Lewis
Organic
Strong
Superbases
Non-nucleophilic
Weak
v
t
e
In chemistry, pH (/piːˈeɪtʃ/) (potential of hydrogen) is a logarithmic scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per liter, of hydrogen ions. More precisely it is the negative of the base 10 logarithm of the activity of the hydrogen ion.[1] Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. Pure water is neutral, at pH 7 (25 °C), being neither an acid nor a base. Contrary to popular belief, the pH value can be less than 0 or greater than 14 for very strong acids and bases respectively.[2]
Measurements of pH are important in agronomy, medicine, chemistry, water treatment, and many other applications.
The pH scale is traceable to a set of standard solutions whose pH is established by international agreement.[3] Primary pH standard values are determined using a concentration cell with transference, by measuring the potential difference between a hydrogen electrode and a standard electrode such as the silver chloride electrode. The pH of aqueous solutions can be measured with a glass electrode and a pH meter, or an indicator.
There are three current theories used to describe Acid–base reactions: Arrhenius, Bronsted-Lowry and Lewis when determining pH.
Contents
[hide]
1 History
2 Definition and measurement
2.1 pH
2.2 p[H]
2.3 pH indicators
2.4 pOH
2.5 Extremes of pH
2.6 Non-aqueous solutions
3 Applications
3.1 pH in soil
3.1.1 Classification of soil pH ranges
3.2 pH in nature
3.3 Seawater
3.4 Living systems
4 Calculations of pH
4.1 Strong acids and bases
4.2 Weak acids and bases
4.3 General method
5 See also
6 References
7 External links
History
The concept of pH was first introduced by the Danish chemist Søren Peder Lauritz Sørensen at the Carlsberg Laboratory in 1909[4] and revised to the modern pH in 1924 to accommodate definitions and measurements in terms of electrochemical cells. In the first papers, the notation had the "H" as a subscript to the lowercase "p", as so: pH.
The exact meaning of the "p" in "pH" is disputed, but according to the Carlsberg Foundation, pH stands for "power of hydrogen".[5] It has also been suggested that the "p" stands for the German Potenz[not in citation given] (meaning "power"), others refer to French puissance (also meaning "power", based on the fact that the Carlsberg Laboratory was French-speaking). Another suggestion is that the "p" stands for the Latin terms pondus hydrogenii (quantity of hydrogen), potentia hydrogenii (capacity of hydrogen), or potential hydrogen. It is also suggested that Sørensen used the letters "p" and "q" (commonly paired letters in mathematics) simply to label the test solution (p) and the reference solution (q).[6] Currently in chemistry, the p stands for "decimal cologarithm of", and is also used in the term pKa, used for acid dissociation constants.[7]
Bacteriologist Alice C. Evans, famed for her work's influence on dairying and food safety, credited William Mansfield Clark and colleagues (of whom she was one) with developing pH measuring methods in the 1910s, with wide influence on laboratory and industrial use thereafter. In her memoir, she does not mention how much, or how little, Clark and colleagues knew about Sørensen's work a few years prior.[8]:10 She said:
In these studies [of bacterial metabolism] Dr. Clark's attention was directed to the effect of acid on the growth of bacteria. He found that it is the intensity of the acid in terms of hydrogen-ion concentration that affects their growth. But existing methods of measuring acidity determined the quantity, not the intensity, of the acid. Next, with his collaborators, Dr. Clark developed accurate methods for measuring hydrogen-ion concentration. These methods replaced the inaccurate titration method of determining acid content in use in biologic laboratories throughout the world. Also they were found to be applicable in many industrial and other processes in which they came into wide usage.[8]:10
The first electronic method for measuring pH was invented by Arnold Orville Beckman, a professor at California Institute of Technology in 1934.[9] It was in response to local citrus grower Sunkist that wanted a better method for quickly testing the pH of lemons they were picking from their nearby orchards.[10]
Definition and measurement
pH
pH is defined as the decimal logarithm of the reciprocal of the hydrogen ion activity, aH+, in a solution.[3]
pH = − log 10  ( a H + ) = log 10  ( 1 a H + ) {\displaystyle {\ce {pH}}=-\log _{10}(a_{{\ce {H+}}})=\log _{10}\left({\frac {1}{a_{{\ce {H+}}}}}\right)}
For example, a solution with a hydrogen ion activity of 5×10−6 = 1/(2×105) (at that level essentially the number of moles of hydrogen ions per liter of solution) has a pH of log10(2×105) = 5.3. For a commonplace example based on the facts that the masses of a mole of water, a mole of hydrogen ions, and a mole of hydroxide ions are respectively 18 g, 1 g, and 17 g, a quantity of 107 moles of pure (pH 7) water, or 180 tonnes (18×107 g), contains close to 1 g of dissociated hydrogen ions (or rather 19 g of H3O+ hydronium ions) and 17 g of hydroxide ions.
Note that pH depends on temperature. For instance at 0 °C the pH of pure water is 7.47. At 25 °C it's 7.00, and at 100 °C it's 6.14.
This definition was adopted because ion-selective electrodes, which are used to measure pH, respond to activity. Ideally, electrode potential, E, follows the Nernst equation, which, for the hydrogen ion can be written as
E = E 0 + R T F ln  ( a H + ) = E 0 − 2.303 R T F pH {\displaystyle E=E^{0}+{\frac {RT}{F}}\ln(a_{{\ce {H+}}})=E^{0}-{\frac {2.303RT}{F}}{\ce {pH}}}
where E is a measured potential, E0 is the standard electrode potential, R is the gas constant, T is the temperature in kelvins, F is the Faraday constant. For H+ number of electrons transferred is one. It follows that electrode potential is proportional to pH when pH is defined in terms of activity. Precise measurement of pH is presented in International Standard ISO 31-8 as follows:[11] A galvanic cell is set up to measure the electromotive force (e.m.f.) between a reference electrode and an electrode sensitive to the hydrogen ion activity when they are both immersed in the same aqueous solution. The reference electrode may be a silver chloride electrode or a calomel electrode. The hydrogen-ion selective electrode is a standard hydrogen electrode.
Reference electrode | concentrated solution of KCl || test solution | H2 | Pt[clarification needed]
Firstly, the cell is filled with a solution of known hydrogen ion activity and the emf, ES, is measured. Then the emf, EX, of the same cell containing the solution of unknown pH is measured.
pH ( X ) = pH ( S ) + E S − E X z {\displaystyle {\ce {pH(X)}}={\ce {pH(S)}}+{\frac {E_{{\ce {S}}}-E_{{\ce {X}}}}{z}}}
The difference between the two measured emf values is proportional to pH. This method of calibration avoids the need to know the standard electrode potential. The proportionality constant, 1/z is ideally equal to 1 2.303 R T / F {\displaystyle {\frac {1}{2.303RT/F}}\ } the "Nernstian slope".
To apply this process in practice, a glass electrode is used rather than the cumbersome hydrogen electrode. A combined glass electrode has an in-built reference electrode. It is calibrated against buffer solutions of known hydrogen ion activity. IUPAC has proposed the use of a set of buffer solutions of known H+ activity.[3] Two or more buffer solutions are used in order to accommodate the fact that the "slope" may differ slightly from ideal. To implement this approach to calibration, the electrode is first immersed in a standard solution and the reading on a pH meter is adjusted to be equal to the standard buffer's value. The reading from a second standard buffer solution is then adjusted, using the "slope" control, to be equal to the pH for that solution. Further details, are given in the IUPAC recommendations.[3] When more than two buffer solutions are used the electrode is calibrated by fitting observed pH values to a straight line with respect to standard buffer values. Commercial standard buffer solutions usually come with information on the value at 25 °C and a correction factor to be applied for other temperatures.
The pH scale is logarithmic and therefore pH is a dimensionless quantity.
p[H]
This was the original definition of Sørensen,[5] which was superseded in favor of pH in 1909. However, it is possible to measure the concentration of hydrogen ions directly, if the electrode is calibrated in terms of hydrogen ion concentrations. One way to do this, which has been used extensively, is to titrate a solution of known concentration of a strong acid with a solution of known concentration of strong alkaline in the presence of a relatively high concentration of background electrolyte. Since the concentrations of acid and alkaline are known, it is easy to calculate the concentration of hydrogen ions so that the measured potential can be correlated with concentrations. The calibration is usually carried out using a Gran plot.[12] The calibration yields a value for the standard electrode potential, E0, and a slope factor, f, so that the Nernst equation in the form
E = E 0 + f 2.303 R T F log  [ H + ] {\displaystyle E=E^{0}+f{\frac {2.303RT}{F}}\log[{\ce {H+}}]}
can be used to derive hydrogen ion concentrations from experimental measurements of E. The slope factor, f, is usually slightly less than one. A slope factor of less than 0.95 indicates that the electrode is not functioning correctly. The presence of background electrolyte ensures that the hydrogen ion activity coefficient is effectively constant during the titration. As it is constant, its value can be set to one by defining the standard state as being the solution containing the background electrolyte. Thus, the effect of using this procedure is to make activity equal to the numerical value of concentration.
The glass electrode (and other ion selective electrodes) should be calibrated in a medium similar to the one being investigated. For instance, if one wishes to measure the pH of a seawater sample, the electrode should be calibrated in a solution resembling seawater in its chemical composition, as detailed below.
The difference between p[H] and pH is quite small. It has been stated[13] that pH = p[H] + 0.04. It is common practice to use the term "pH" for both types of measurement.
pH indicators
Main article: universal indicator
Chart showing the variation of color of universal indicator paper with pH
Indicators may be used to measure pH, by making use of the fact that their color changes with pH. Visual comparison of the color of a test solution with a standard color chart provides a means to measure pH accurate to the nearest whole number. More precise measurements are possible if the color is measured spectrophotometrically, using a colorimeter or spectrophotometer. Universal indicator consists of a mixture of indicators such that there is a continuous color change from about pH 2 to pH 10. Universal indicator paper is made from absorbent paper that has been impregnated with universal indicator. Another method of measuring pH is using an electronic pH meter.
pOH
Relation between p[OH] and p[H] (red = acidic region, blue = basic region)
pOH is sometimes used as a measure of the concentration of hydroxide ions. OH−. pOH values are derived from pH measurements. The concentration of hydroxide ions in water is related to the concentration of hydrogen ions by
[ OH − ] = K W [ H + ] {\displaystyle [{\ce {OH^-}}]={\frac {K_{{\ce {W}}}}{[{\ce {H^+}}]}}}
where KW is the self-ionisation constant of water. Taking logarithms
pOH = p K W − pH {\displaystyle {\ce {pOH}}={\ce {p}}K_{{\ce {W}}}-{\ce {pH}}}
So, at room temperature, pOH ≈ 14 − pH. However this relationship is not strictly valid in other circumstances, such as in measurements of soil alkalinity.
Extremes of pH
Measurement of pH below about 2.5 (ca. 0.003 mol dm−3 acid) and above about 10.5 (ca. 0.0003 mol dm−3 alkaline) requires special procedures because, when using the glass electrode, the Nernst law breaks down under those conditions. Various factors contribute to this. It cannot be assumed that liquid junction potentials are independent of pH.[14] Also, extreme pH implies that the solution is concentrated, so electrode potentials are affected by ionic strength variation. At high pH the glass electrode may be affected by "alkaline error", because the electrode becomes sensitive to the concentration of cations such as Na+ and K+ in the solution.[15] Specially constructed electrodes are available which partly overcome these problems.
Runoff from mines or mine tailings can produce some very low pH values.[16]
Non-aqueous solutions
Hydrogen ion concentrations (activities) can be measured in non-aqueous solvents. pH values based on these measurements belong to a different scale from aqueous pH values, because activities relate to different standard states. Hydrogen ion activity, aH+, can be defined[17][18] as:
a H + = exp  ( μ H + − μ H + ⊖ R T ) {\displaystyle a_{{\ce {H+}}}=\exp \left({\frac {\mu _{{\ce {H+}}}-\mu _{{\ce {H+}}}^{\ominus }}{RT}}\right)}
where μH+ is the chemical potential of the hydrogen ion, μ H + ⊖ {\displaystyle \mu _{{\ce {H+}}}^{\ominus }} is its chemical potential in the chosen standard state, R is the gas constant and T is the thermodynamic temperature. Therefore, pH values on the different scales cannot be compared directly due to different solvated proton ions such as lyonium ions, requiring an intersolvent scale which involves the transfer activity coefficient of hydronium/lyonium ion.
pH is an example of an acidity function. Other acidity functions can be defined. For example, the Hammett acidity function, H0, has been developed in connection with superacids.
The concept of "Unified pH scale" has been developed on the basis of the absolute chemical potential of the proton. This scale applies to liquids, gases and even solids.[19]
Applications
Pure water is neutral. When an acid is dissolved in water, the pH will be less than 7 (25 °C). When a base, or alkali, is dissolved in water, the pH will be greater than 7. A solution of a strong acid, such as hydrochloric acid, at concentration 1 mol dm−3 has a pH of 0. A solution of a strong alkali, such as sodium hydroxide, at concentration 1 mol dm−3, has a pH of 14. Thus, measured pH values will lie mostly in the range 0 to 14, though negative pH values and values above 14 are entirely possible. Since pH is a logarithmic scale, a difference of one pH unit is equivalent to a tenfold difference in hydrogen ion concentration.
The pH of neutrality is not exactly 7 (25 °C), although this is a good approximation in most cases. Neutrality is defined as the condition where [H+] = [OH−] (or the activities are equal). Since self-ionization of water holds the product of these concentration [H+]×[OH−] = Kw, it can be seen that at neutrality [H+] = [OH−] =√Kw, or pH = pKw/2. pKw is approximately 14 but depends on ionic strength and temperature, and so the pH of neutrality does also. Pure water and a solution of NaCl in pure water are both neutral, since dissociation of water produces equal numbers of both ions. However the pH of the neutral NaCl solution will be slightly different from that of neutral pure water because the hydrogen and hydroxide ions' activity is dependent on ionic strength, so Kw varies with ionic strength.
If pure water is exposed to air it becomes mildly acidic. This is because water absorbs carbon dioxide from the air, which is then slowly converted into bicarbonate and hydrogen ions (essentially creating carbonic acid).
CO 2 + H 2 O ↽ − − ⇀ HCO 3 − + H + {\displaystyle {\ce {CO2 + H2O <=> HCO3^- + H+}}}
pH in soil
Classification of soil pH ranges
The United States Department of Agriculture Natural Resources Conservation Service, formerly Soil Conservation Service classifies soil pH ranges as follows: [20]
Nutritional elements availability within soil varies with pH. Light blue color represents the ideal range for most of the plants.
Denomination
pH range
Ultra acidic < 3.5
Extremely acidic 3.5–4.4
Very strongly acidic 4.5–5.0
Strongly acidic 5.1–5.5
Moderately acidic 5.6–6.0
Slightly acidic 6.1–6.5
Neutral 6.6–7.3
Slightly alkaline 7.4–7.8
Moderately alkaline 7.9–8.4
Strongly alkaline 8.5–9.0
Very strongly alkaline > 9.0
pH in nature
Lemon juice tastes sour because it contains 5% to 6% citric acid and has a pH of 2.2. (high acidity)
pH-dependent plant pigments that can be used as pH indicators occur in many plants, including hibiscus, red cabbage (anthocyanin) and red wine. The juice of citrus fruits is acidic mainly because it contains citric acid. Other carboxylic acids occur in many living systems. For example, lactic acid is produced by muscle activity. The state of protonation of phosphate derivatives, such as ATP, is pH-dependent. The functioning of the oxygen-transport enzyme hemoglobin is affected by pH in a process known as the Root effect.
Seawater
See also: Ocean acidification
The pH of seawater is typically limited to a range between 7.5 and 8.4.[21] It plays an important role in the ocean's carbon cycle, and there is evidence of ongoing ocean acidification caused by carbon dioxide emissions.[22] However, pH measurement is complicated by the chemical properties of seawater, and several distinct pH scales exist in chemical oceanography.[23]
As part of its operational definition of the pH scale, the IUPAC defines a series of buffer solutions across a range of pH values (often denoted with NBS or NIST designation). These solutions have a relatively low ionic strength (≈0.1) compared to that of seawater (≈0.7), and, as a consequence, are not recommended for use in characterizing the pH of seawater, since the ionic strength differences cause changes in electrode potential. To resolve this problem, an alternative series of buffers based on artificial seawater was developed.[24] This new series resolves the problem of ionic strength differences between samples and the buffers, and the new pH scale is referred to as the 'total scale', often denoted as pHT. The total scale was defined using a medium containing sulfate ions. These ions experience protonation, H+ + SO2−
4 ⇌ HSO−
4, such that the total scale includes the effect of both protons (free hydrogen ions) and hydrogen sulfate ions:
[H+]T = [H+]F + [HSO−
4]
An alternative scale, the 'free scale', often denoted 'pHF', omits this consideration and focuses solely on [H+]F, in principle making it a simpler representation of hydrogen ion concentration. Only [H+]T can be determined,[25] therefore [H+]F must be estimated using the [SO2−
4] and the stability constant of HSO−
4, K*
S:
[H+]F = [H+]T − [HSO−
4] = [H+]T ( 1 + [SO2−
4] / K*
S )−1
However, it is difficult to estimate K*
S in seawater, limiting the utility of the otherwise more straightforward free scale.
Another scale, known as the 'seawater scale', often denoted 'pHSWS', takes account of a further protonation relationship between hydrogen ions and fluoride ions, H+ + F− ⇌ HF. Resulting in the following expression for [H+]SWS:
[H+]SWS = [H+]F + [HSO−
4] + [HF]
However, the advantage of considering this additional complexity is dependent upon the abundance of fluoride in the medium. In seawater, for instance, sulfate ions occur at much greater concentrations (>400 times) than those of fluoride. As a consequence, for most practical purposes, the difference between the total and seawater scales is very small.
The following three equations summarise the three scales of pH:
pHF = − log [H+]F
pHT = − log ( [H+]F + [HSO−
4] ) = − log [H+]T
pHSWS = − log ( [H+]F + [HSO−
4] + [HF] ) = − log [H+]SWS
In practical terms, the three seawater pH scales differ in their values by up to 0.12 pH units, differences that are much larger than the accuracy of pH measurements typically required, in particular, in relation to the ocean's carbonate system.[23] Since it omits consideration of sulfate and fluoride ions, the free scale is significantly different from both the total and seawater scales. Because of the relative unimportance of the fluoride ion, the total and seawater scales differ only very slightly.
Living systems
pH in living systems[26]
Compartment
pH
Gastric acid 1.5-3.5[27]
Lysosomes 4.5
Human skin 4.7[28]
Granules of chromaffin cells 5.5
Urine 6.0
Cytosol 7.2
Blood (natural pH) 7.34–7.45
Cerebrospinal fluid (CSF) 7.5
Mitochondrial matrix 7.5
Pancreas secretions 8.1
The pH of different cellular compartments, body fluids, and organs is usually tightly regulated in a process called acid-base homeostasis. The most common disorder in acid-base homeostasis is acidosis, which means an acid overload in the body, generally defined by pH falling below 7.35. Alkalosis is the opposite condition, with blood pH being excessively high.
The pH of blood is usually slightly basic with a value of pH 7.365. This value is often referred to as physiological pH in biology and medicine. Plaque can create a local acidic environment that can result in tooth decay by demineralization. Enzymes and other proteins have an optimum pH range and can become inactivated or denatured outside this range.
Calculations of pH
The calculation of the pH of a solution containing acids and/or bases is an example of a chemical speciation calculation, that is, a mathematical procedure for calculating the concentrations of all chemical species that are present in the solution. The complexity of the procedure depends on the nature of the solution. For strong acids and bases no calculations are necessary except in extreme situations. The pH of a solution containing a weak acid requires the solution of a quadratic equation. The pH of a solution containing a weak base may require the solution of a cubic equation. The general case requires the solution of a set of non-linear simultaneous equations.
A complicating factor is that water itself is a weak acid and a weak base (see amphoterism). It dissociates according to the equilibrium
2 H 2 O ↽ − − ⇀ H 3 O + ( aq ) + OH − ( aq ) {\displaystyle {\ce {2H2O<=>{H3O+(aq)}+{OH^{-}(aq)}}}}
with a dissociation constant, Kw defined as
K w = [ H + ] [ OH − ] {\displaystyle K_{w}={\ce {[H+][OH^-]}}}
where [H+] stands for the concentration of the aqueous hydronium ion and [OH−] represents the concentration of the hydroxide ion. This equilibrium needs to be taken into account at high pH and when the solute concentration is extremely low.
Strong acids and bases
Strong acids and bases are compounds that, for practical purposes, are completely dissociated in water. Under normal circumstances this means that the concentration of hydrogen ions in acidic solution can be taken to be equal to the concentration of the acid. The pH is then equal to minus the logarithm of the concentration value. Hydrochloric acid (HCl) is an example of a strong acid. The pH of a 0.01M solution of HCl is equal to −log10(0.01), that is, pH = 2. Sodium hydroxide, NaOH, is an example of a strong base. The p[OH] value of a 0.01M solution of NaOH is equal to −log10(0.01), that is, p[OH] = 2. From the definition of p[OH] above, this means that the pH is equal to about 12. For solutions of sodium hydroxide at higher concentrations the self-ionization equilibrium must be taken into account.
Self-ionization must also be considered when concentrations are extremely low. Consider, for example, a solution of hydrochloric acid at a concentration of 5×10−8M. The simple procedure given above would suggest that it has a pH of 7.3. This is clearly wrong as an acid solution should have a pH of less than 7. Treating the system as a mixture of hydrochloric acid and the amphoteric substance water, a pH of 6.89 results.[29]
Weak acids and bases
A weak acid or the conjugate acid of a weak base can be treated using the same formalism.
{ Acid : HA ↽ − − ⇀ H + + A − Base : HA + ↽ − − ⇀ H + + A {\displaystyle {\begin{cases}{\ce {Acid:}}&{\ce {HA <=> H+ + A^-}}\\{\ce {Base:}}&{\ce {HA+ <=> H+ + A}}\end{cases}}}
First, an acid dissociation constant is defined as follows. Electrical charges are omitted from subsequent equations for the sake of generality
K a = [ H ] [ A ] [ HA ] {\displaystyle K_{a}={\frac {{\ce {[H] [A]}}}{{\ce {[HA]}}}}}
and its value is assumed to have been determined by experiment. This being so, there are three unknown concentrations, [HA], [H+] and [A−] to determine by calculation. Two additional equations are needed. One way to provide them is to apply the law of mass conservation in terms of the two "reagents" H and A.
C A = [ A ] + [ HA ] {\displaystyle C_{{\ce {A}}}={\ce {[A]}}+{\ce {[HA]}}}
C H = [ H ] + [ HA ] {\displaystyle C_{{\ce {H}}}={\ce {[H]}}+{\ce {[HA]}}}
C stands for analytical concentration. In some texts, one mass balance equation is replaced by an equation of charge balance. This is satisfactory for simple cases like this one, but is more difficult to apply to more complicated cases as those below. Together with the equation defining Ka, there are now three equations in three unknowns. When an acid is dissolved in water CA = CH = Ca, the concentration of the acid, so [A] = [H]. After some further algebraic manipulation an equation in the hydrogen ion concentration may be obtained.
[ H ] 2 + K a [ H ] − K a C a = 0 {\displaystyle [{\ce {H}}]^{2}+K_{a}[{\ce {H}}]-K_{a}C_{a}=0}
Solution of this quadratic equation gives the hydrogen ion concentration and hence p[H] or, more loosely, pH. This procedure is illustrated in an ICE table which can also be used to calculate the pH when some additional (strong) acid or alkaline has been added to the system, that is, when CA ≠ CH.
For example, what is the pH of a 0.01M solution of benzoic acid, pKa = 4.19?
Step 1: K a = 10 − 4.19 = 6.46 × 10 − 5 {\displaystyle K_{a}=10^{-4.19}=6.46\times 10^{-5}}
Step 2: Set up the quadratic equation. [ H ] 2 + 6.46 × 10 − 5 [ H ] − 6.46 × 10 − 7 = 0 {\displaystyle [{\ce {H}}]^{2}+6.46\times 10^{-5}[{\ce {H}}]-6.46\times 10^{-7}=0}
Step 3: Solve the quadratic equation. [ H + ] = 7.74 × 10 − 4 ; p H = 3.11 {\displaystyle [{\ce {H+}}]=7.74\times 10^{-4};\quad \mathrm {pH} =3.11}
For alkaline solutions an additional term is added to the mass-balance equation for hydrogen. Since addition of hydroxide reduces the hydrogen ion concentration, and the hydroxide ion concentration is constrained by the self-ionization equilibrium to be equal to K w [ H + ] {\displaystyle {\frac {K_{w}}{{\ce {[H+]}}}}}
C H = [ H ] + [ HA ] − K w [ H ] {\displaystyle C_{\ce {H}}={\frac {[{\ce {H}}]+[{\ce {HA}}]-K_{w}}{\ce {[H]}}}}
In this case the resulting equation in [H] is a cubic equation.
General method
Some systems, such as with polyprotic acids, are amenable to spreadsheet calculations.[30] With three or more reagents or when many complexes are formed with general formulae such as ApBqHr,the following general method can be used to calculate the pH of a solution. For example, with three reagents, each equilibrium is characterized by an equilibrium constant, β.
[ A p B q H r ] = β p q r [ A ] p [ B ] q [ H ] r {\displaystyle [{\ce {A}}_{p}{\ce {B}}_{q}{\ce {H}}_{r}]=\beta _{pqr}[{\ce {A}}]^{p}[{\ce {B}}]^{q}[{\ce {H}}]^{r}}
Next, write down the mass-balance equations for each reagent:
C A = [ A ] + Σ p β p q r [ A ] p [ B ] q [ H ] r C B = [ B ] + Σ q β p q r [ A ] p [ B ] q [ H ] r C H = [ H ] + Σ r β p q r [ A ] p [ B ] q [ H ] r − K w [ H ] − 1 {\displaystyle {\begin{aligned}C_{\ce {A}}&=[{\ce {A}}]+\Sigma p\beta _{pqr}[{\ce {A}}]^{p}[{\ce {B}}]^{q}[{\ce {H}}]^{r}\\C_{\ce {B}}&=[{\ce {B}}]+\Sigma q\beta _{pqr}[{\ce {A}}]^{p}[{\ce {B}}]^{q}[{\ce {H}}]^{r}\\C_{\ce {H}}&=[{\ce {H}}]+\Sigma r\beta _{pqr}[{\ce {A}}]^{p}[{\ce {B}}]^{q}[{\ce {H}}]^{r}-K_{w}[{\ce {H}}]^{-1}\end{aligned}}}
Note that there are no approximations involved in these equations, except that each stability constant is defined as a quotient of concentrations, not activities. Much more complicated expressions are required if activities are to be used.
There are 3 non-linear simultaneous equations in the three unknowns, [A], [B] and [H]. Because the equations are non-linear, and because concentrations may range over many powers of 10, the solution of these equations is not straightforward. However, many computer programs are available which can be used to perform these calculations. There may be more than three reagents. The calculation of hydrogen ion concentrations, using this formalism, is a key element in the determination of equilibrium constants by potentiometric titration.
See also
Alkaline diet
Arterial blood gas
Bel
Chemical equilibrium
pCO2
References
Jump up ^ Bates, Roger G. Determination of pH: theory and practice. Wiley, 1973.
Jump up ^ Lim, Kieran F. (2006). "Negative pH Does Exist". Journal of Chemical Education. 83 (10): 1465. Bibcode:2006JChEd..83.1465L. doi:10.1021/ed083p1465.
^ Jump up to: a b c d Covington, A. K.; Bates, R. G.; Durst, R. A. (1985). "Definitions of pH scales, standard reference values, measurement of pH, and related terminology" (PDF). Pure Appl. Chem. 57 (3): 531–542. doi:10.1351/pac198557030531. Archived (PDF) from the original on 24 September 2007.
Jump up ^ Sørensen, S. P. L. (1909). "Über die Messung und die Bedeutung der Wasserstoffionenkonzentration bei enzymatischen Prozessen". Biochem. Zeitschr. 21: 131–304. Two other publications appeared in 1909 one in French and one in Danish
^ Jump up to: a b "Carlsberg Group Company History Page". Carlsberggroup.com. Archived from the original on 18 January 2014. Retrieved 7 May 2013.
Jump up ^ Myers, Rollie J. (2010). "One-Hundred Years of pH". Journal of Chemical Education. 87: 30–32. Bibcode:2010JChEd..87...30M. doi:10.1021/ed800002c.
Jump up ^ Nørby, Jens (2000). "The origin and the meaning of the little p in pH". Trends in Biochemical Sciences. 25 (1): 36–37. doi:10.1016/S0968-0004(99)01517-0. PMID 10637613.
^ Jump up to: a b Evans, Alice C. (1963). "Memoirs" (PDF). NIH Office of History. National Institutes of Health Office of History. Retrieved 2018-03-27.
Jump up ^ "ORIGINS: BIRTH OF THE PH METER". CalTech Engineering & Science Magazine. Retrieved 11 March 2018.
Jump up ^ Tetrault, Sharon. "The Beckmans". Orange Coast. Orange Coast Magazine. Retrieved 11 March 2018.
Jump up ^ Quantities and units – Part 8: Physical chemistry and molecular physics, Annex C (normative): pH. International Organization for Standardization, 1992.
Jump up ^ Rossotti, F.J.C.; Rossotti, H. (1965). "Potentiometric titrations using Gran plots: A textbook omission". J. Chem. Educ. 42 (7): 375–378. Bibcode:1965JChEd..42..375R. doi:10.1021/ed042p375.
Jump up ^ Mendham, J.; Denney, R. C.; Barnes, J. D.; Thomas, M. J. K. (2000), Vogel's Quantitative Chemical Analysis (6th ed.), New York: Prentice Hall, ISBN 0-582-22628-7 , Section 13.23, "Determination of pH"
Jump up ^ Feldman, Isaac (1956). "Use and Abuse of pH measurements". Analytical Chemistry. 28 (12): 1859–1866. doi:10.1021/ac60120a014.
Jump up ^ Mendham, J.; Denney, R. C.; Barnes, J. D.; Thomas, M. J. K. (2000), Vogel's Quantitative Chemical Analysis (6th ed.), New York: Prentice Hall, ISBN 0-582-22628-7 , Section 13.19 The glass electrode
Jump up ^ Nordstrom, D. Kirk; Alpers, Charles N. (March 1999). "Negative pH, efflorescent mineralogy, and consequences for environmental restoration at the Iron Mountain Superfund site, California". Proceedings of the National Academy of Sciences of the United States of America. PNAS. 96 (7): 3455–62. Bibcode:1999PNAS...96.3455N. doi:10.1073/pnas.96.7.3455. PMC 34288  . PMID 10097057.
Jump up ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "activity (relative activity), a".
Jump up ^ International Union of Pure and Applied Chemistry (1993). Quantities, Units and Symbols in Physical Chemistry, 2nd edition, Oxford: Blackwell Science. ISBN 0-632-03583-8. pp. 49–50. Electronic version.
Jump up ^ Himmel, D.; Goll, S. K.; Leito, I.; Krossing, I. (2010). "A Unified pH Scale for all Phases". Angew. Chem. Int. Ed. 49 (38): 6885–6888. doi:10.1002/anie.201000252.
Jump up ^ Soil Survey Division Staff. "Soil survey manual.1993. Chapter 3, selected chemical properties". Soil Conservation Service. U.S. Department of Agriculture Handbook 18. Archived from the original on 14 May 2011. Retrieved 12 March 2011.
Jump up ^ Chester, Jickells, Roy, Tim (2012). Marine Geochemistry. Blackwell Publishing. ISBN 978-1-118-34907-6.
Jump up ^ Royal Society (2005). Ocean acidification due to increasing atmospheric carbon dioxide (PDF). ISBN 0-85403-617-2. Archived (PDF) from the original on 16 July 2010.
^ Jump up to: a b Zeebe, R. E. and Wolf-Gladrow, D. (2001) CO2 in seawater: equilibrium, kinetics, isotopes, Elsevier Science B.V., Amsterdam, Netherlands ISBN 0-444-50946-1
Jump up ^ Hansson, I. (1973). "A new set of pH-scales and standard buffers for seawater". Deep-Sea Research. 20 (5): 479–491. Bibcode:1973DSROA..20..479H. doi:10.1016/0011-7471(73)90101-0.
Jump up ^ Dickson, A. G. (1984). "pH scales and proton-transfer reactions in saline media such as sea water". Geochim. Cosmochim. Acta. 48 (11): 2299–2308. Bibcode:1984GeCoA..48.2299D. doi:10.1016/0016-7037(84)90225-4.
Jump up ^ Boron, Walter, F.; Boulpaep, E.L. (2004). Medical Physiology: A Cellular And Molecular Approach. Elsevier/Saunders. ISBN 1-4160-2328-3.
Jump up ^ Marieb EN, Hoehn K (2010). Human anatomy & physiology. San Francisco: Benjamin Cummings. ISBN 0-8053-9591-1.
Jump up ^ Lambers, H.; Piessens, S.; Bloem, A.; Pronk, H.; Finkel, P. (2006-10-01). "Natural skin surface pH is on average below 5, which is beneficial for its resident flora". International Journal of Cosmetic Science. 28 (5): 359–370. doi:10.1111/j.1467-2494.2006.00344.x. ISSN 1468-2494. PMID 18489300.
Jump up ^ Maloney, Chris. "pH calculation of a very small concentration of a strong acid". Archived from the original on 8 July 2011. Retrieved 13 March 2011.
Jump up ^ Billo, E.J. (2011). EXCEL for Chemists (3rd ed.). Wiley-VCH. ISBN 978-0-470-38123-6.
External links
Wikimedia Commons has media related to pH.
The pH Scale
Chem1 Virtual Textbook, Acid-base Equilibria and Calculations
Red Cabbage pH Indicator
Food and Foodstuff – pH Values
Online pH Calculator for about 100 inorganic Acids, Bases, and Salts
[hide]
v
t
e
Wastewater
Sources
Acid mine drainage
Ballast water
Bathroom
Blackwater (coal)
Blackwater (waste)
Boiler blowdown
Brine
Combined sewer
Cooling tower
Cooling water
Fecal sludge
Greywater
Infiltration/Inflow
Industrial effluent
Ion exchange
Leachate
Manure
Papermaking
Produced water
Return flow
Reverse osmosis
Sanitary sewer
Septage
Sewage
Sewage sludge
Toilet
Urban runoff
Quality indicators
Adsorbable organic halides
Biochemical oxygen demand
Chemical oxygen demand
Coliform index
Dissolved oxygen
Heavy metals
pH
Salinity
Temperature
Total dissolved solids
Total suspended solids
Turbidity
Treatment options
Activated sludge
Aerated lagoon
Agricultural wastewater treatment
API oil-water separator
Carbon filtration
Chlorination
Clarifier
Constructed wetland
Decentralized wastewater system
Extended aeration
Facultative lagoon
Fecal sludge management
Filtration
Imhoff tank
Industrial wastewater treatment
Ion exchange
Membrane bioreactor
Reverse osmosis
Rotating biological contactor
Secondary treatment
Sedimentation
Septic tank
Settling basin
Sewage sludge treatment
Sewage treatment
Sewer mining
Stabilization pond
Trickling filter
Ultraviolet germicidal irradiation
UASB
Vermifilter
Wastewater treatment plant
Disposal options
Combined sewer
Evaporation pond
Groundwater recharge
Infiltration basin
Injection well
Irrigation
Marine dumping
Marine outfall
Reclaimed water
Sanitary sewer
Septic drain field
Sewage farm
Storm drain
Surface runoff
Vacuum sewer
Retrieved from "https://en.wikipedia.org/w/index.php?title=PH&oldid=838425269"
Categories:
Acid–base chemistry
Equilibrium chemistry
Units of measurement
Water quality indicators
Logarithmic scales of measurement
General chemistry
Hidden categories:
Wikipedia semi-protected pages
Wikipedia indefinitely move-protected pages
All articles with failed verification
Articles with failed verification from December 2017
Wikipedia articles needing clarification from October 2014
Commons category with local link different than on Wikidata
Use dmy dates from March 2012
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Create account
Log in
Namespaces
Article
Talk
Variants
Views
Read
View source
View history
More
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Wikipedia store
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact page
Tools
What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Wikidata item
Cite this page
Print/export
Create a book
Download as PDF
Printable version
In other projects
Wikimedia Commons
Languages
Afrikaans
Alemannisch
العربية
Asturianu
বাংলা
Bân-lâm-gú
Беларуская
भोजपुरी
Български
Bosanski
Català
Čeština
Cymraeg
Dansk
Davvisámegiella
Deutsch
Eesti
Ελληνικά
Español
Esperanto
Euskara
فارسی
Français
Gaeilge
Galego
客家語/Hak-kâ-ngî
한국어
Հայերեն
हिन्दी
Hrvatski
Ido
Bahasa Indonesia
Interlingua
Íslenska
Italiano
עברית
ಕನ್ನಡ
Kapampangan
Қазақша
Kiswahili
Kreyòl ayisyen
Kurdî
Latina
Latviešu
Lietuvių
Magyar
Македонски
മലയാളം
मराठी
Bahasa Melayu
Монгол
မြန်မာဘာသာ
Nederlands
日本語
Nordfriisk
Norsk
Norsk nynorsk
Novial
Occitan
Oʻzbekcha/ўзбекча
ਪੰਜਾਬੀ
پنجابی
Plattdüütsch
Polski
Português
Română
Русский
Scots
Shqip
Sicilianu
Simple English
Slovenčina
Slovenščina
Soomaaliga
کوردی
Српски / srpski
Srpskohrvatski / српскохрватски
Basa Sunda
Suomi
Svenska
Tagalog
தமிழ்
తెలుగు
ไทย
Türkçe
Українська
Tiếng Việt
文言
West-Vlams
Winaray
粵語
中文
Kabɩyɛ
84 more
Edit links
This page was last edited on 26 April 2018, at 23:01.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
Privacy policy
About Wikipedia
Disclaimers
Contact Wikipedia
Developers
Cookie statement
Mobile view
Enable previews

tag: div

attr: id class

value: mw-page-base noprint

key: html

type: local

value: mw-head-base noprint

tag: a

tag: img

attr: alt src width height srcset data-file-width data-file-height

attr: href title

value: This article is semi-protected until February 3, 2020.

attr: class id

attr: id class lang

value: firstHeading firstHeading en

value: siteSub noprint

value: jump-to-nav mw-jump

attr: href class title

value:
/wiki/PH_(disambiguation)
mw-disambig
PH (disambiguation)

value:
note
hatnote navigation-not-searchable

attr: alt src width height class srcset data-file-width data-file-height

attr: href class

attr: class style

tag: th

tag: tr

tag: li

value: padding:0 0.1em 0.4em;padding:0.2em 0 0.75em;

value:
/wiki/Strong_acid
mw-redirect
Strong acid

value:
/wiki/Dibasic_acid
mw-redirect
Dibasic acid

value: float:right;clear:right;width:22.0em;margin:0 0 1.0em 1.0em;background:#f9f9f9;border:1px solid #aaa;padding:0.2em;border-spacing:0.4em 0;text-align:center;line-height:1.4em;font-size:88%

value:
/wiki/Activity_(chemistry)
mw-redirect
Activity (chemistry)

value:
/wiki/Basic_(chemistry)
mw-redirect
Basic (chemistry)

value:
/wiki/Hydrogen_electrode
mw-redirect
Hydrogen electrode

value:
/wiki/Danish_people
mw-redirect
Danish people

value: The material near this tag failed verification of its source citation(s). (December 2017)

value:
/wiki/Latin_language
mw-redirect
Latin language

value: vertical-align: -2.505ex; width:34.984ex; height:6.176ex;

value:
/wiki/Hydroxide_ion
mw-redirect
Hydroxide ion

value:
/wiki/Ion-selective_electrode
mw-redirect
Ion-selective electrode

value: vertical-align: -1.838ex; width:44.187ex; height:5.176ex;

value: The text near this tag may need clarification or removal of jargon. (October 2014)

value:
noprint Inline-Template
margin-left:0.1em; white-space:nowrap;

value: vertical-align: -1.838ex; width:28.382ex; height:5.343ex;

value: {\displaystyle {\frac {1}{2.303RT/F}}\ }

value: vertical-align: -2.671ex; width:13.017ex; height:6.009ex;

value: vertical-align: -1.838ex; width:29.281ex; height:5.176ex;

value: vertical-align: -2.838ex; width:14.838ex; height:6.343ex;

value: {\displaystyle {\ce {pOH}}={\ce {p}}K_{{\ce {W}}}-{\ce {pH}}}

value: vertical-align: -0.671ex; width:19.005ex; height:2.509ex;

value:
/wiki/Alkaline_soils
mw-redirect
Alkaline soils

value: vertical-align: -3.171ex; width:26.043ex; height:7.509ex;

value: {\displaystyle \mu _{{\ce {H+}}}^{\ominus }}

value: vertical-align: -1.338ex; width:4.069ex; height:3.509ex;

value: {\displaystyle {\ce {CO2 + H2O <=> HCO3^- + H+}}}

value: vertical-align: -1.005ex; width:29.469ex; height:3.343ex;

value:
/wiki/Lemon_juice
mw-redirect
Lemon juice

value:
/wiki/Plant_pigment
mw-redirect
Plant pigment

value:
/wiki/National_Bureau_of_Standards
mw-redirect
National Bureau of Standards

value: National Institute of Standards and Technology

value:
/wiki/Acid-base_homeostasis
mw-redirect
Acid-base homeostasis

value:
/wiki/Cubic_equation
mw-redirect
Cubic equation

value:
/wiki/Simultaneous_equation
mw-redirect
Simultaneous equation

value: vertical-align: -1.005ex; width:33.22ex; height:3.343ex;

value: vertical-align: -0.838ex; width:17.681ex; height:3.009ex;

value:
/wiki/Hydronium_ion
mw-redirect
Hydronium ion

value:
/wiki/Strong_base
mw-redirect
Strong base

attr: columnalign rowspacing columnspacing displaystyle

value: vertical-align: -2.505ex; width:28.348ex; height:6.176ex;

value: vertical-align: -2.671ex; width:13.083ex; height:6.509ex;

value:
/wiki/Mass_conservation
mw-redirect
Mass conservation

value: vertical-align: -0.838ex; width:16.882ex; height:2.843ex;

value:
/wiki/Analytical_concentration
mw-redirect
Analytical concentration

value: vertical-align: -0.838ex; width:25.983ex; height:3.176ex;

value: vertical-align: -0.671ex; width:27.663ex; height:3.009ex;

value: vertical-align: -0.838ex; width:40.334ex; height:3.176ex;

value: vertical-align: -0.838ex; width:32.903ex; height:3.176ex;

value: {\displaystyle {\frac {K_{w}}{{\ce {[H+]}}}}}

value: vertical-align: -2.838ex; width:5.384ex; height:6.176ex;

value: vertical-align: -2.671ex; width:23.941ex; height:6.509ex;

value: vertical-align: -1.005ex; width:28.452ex; height:3.009ex;

value: right left right left right left right left right left right left

value: 0em 2em 0em 2em 0em 2em 0em 2em 0em 2em 0em

value: vertical-align: -4.338ex; width:43.079ex; height:9.676ex;

value:
/wiki/Arterial_blood_gas
mw-redirect
Arterial blood gas

value:
nofollow
external text
//doi.org/10.1021%2Fed083p1465

value:
nofollow
external text
//doi.org/10.1351%2Fpac198557030531

value:
nofollow
external text
//doi.org/10.1021%2Fed800002c

value:
/wiki/PubMed_Identifier
mw-redirect
PubMed Identifier

value:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/10637613

value: International Organization for Standardization

value:
nofollow
external text
//doi.org/10.1021%2Fed042p375

value:
nofollow
external text
//doi.org/10.1021%2Fac60120a014

value:
nofollow
external text
//doi.org/10.1073%2Fpnas.96.7.3455

attr: alt src title width height srcset data-file-width data-file-height

value:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/10097057

value: International Union of Pure and Applied Chemistry

value:
nofollow
external text
http://goldbook.iupac.org/A00115.html

value: Quantities, Units and Symbols in Physical Chemistry

value:
/wiki/Angew._Chem._Int._Ed.
mw-redirect
Angew. Chem. Int. Ed.

value:
nofollow
external text
//doi.org/10.1002%2Fanie.201000252

value:
nofollow
external text
//www.worldcat.org/issn/1468-2494

value:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/18489300

value: -moz-column-width: 30em; -webkit-column-width: 30em; column-width: 30em; list-style-type: decimal;

value:
nofollow
external text
http://www.aqion.onl

value: Ballast water discharge and the environment

value:
/wiki/Fecal_sludge
mw-redirect
Fecal sludge

value:
/wiki/Dissolved_oxygen
mw-redirect
Dissolved oxygen

value:
/wiki/Heavy_metal_(chemistry)
mw-redirect
Heavy metal (chemistry)

value:
/wiki/API_oil-water_separator
mw-redirect
API oil-water separator

value:
/wiki/Carbon_filtration
mw-redirect
Carbon filtration

value:
/wiki/Stabilization_pond
mw-redirect
Stabilization pond

value: Upflow anaerobic sludge blanket digestion

value:
/wiki/Wastewater_treatment_plant
mw-redirect
Wastewater treatment plant

value:
/wiki/Marine_dumping
mw-redirect
Marine dumping

value: nowraplinks collapsible autocollapse navbox-inner

value: navigation navbox Wastewater padding:3px

value: Category:Logarithmic scales of measurement

value: Category:Wikipedia indefinitely move-protected pages

value: Category:All articles with failed verification

value: Category:Articles with failed verification from December 2017

value: Category:Wikipedia articles needing clarification from October 2014

value: Category:Commons category with local link different than on Wikidata

value: Discussion about edits from this IP address [ctrl-alt-n]

value: A list of edits made from this IP address [ctrl-alt-y]

value: You are encouraged to create an account and log in; however, it is not mandatory

value: You're encouraged to log in; however, it's not mandatory. [ctrl-alt-o]

value:
/wiki/PH
View the content page [ctrl-alt-c]
c

value: Discussion about the content page [ctrl-alt-t]

value: p-namespaces navigation vectorTabs p-namespaces-label

value:
p-variants
navigation
vectorMenu emptyPortlet
p-variants-label

value:
This page is protected.
You can view its source [ctrl-alt-e]

value: Past revisions of this page [ctrl-alt-h]

value: p-views navigation vectorTabs p-views-label

value:
p-cactions
navigation
vectorMenu emptyPortlet
p-cactions-label

value:
mw-wiki-logo
/wiki/Main_Page
Visit the main page

value:
/wiki/Main_Page
Visit the main page [ctrl-alt-z]
z

value: Featured content – the best of Wikipedia

value: Find background information on current events

value:
/wiki/Special:Random
Load a random article [ctrl-alt-x]
x

value: portal navigation p-navigation p-navigation-label

value: Guidance on how to use and edit Wikipedia

value: portal navigation p-wikibase-otherprojects p-wikibase-otherprojects-label

value:
https://af.wikipedia.org/wiki/PH
PH – Afrikaans
af
af
interlanguage-link-target

value:
interlanguage-link interwiki-af
display: none;

value:
https://als.wikipedia.org/wiki/PH-Wert
PH-Wert – Alemannisch
als
als
interlanguage-link-target

value:
interlanguage-link interwiki-als
display: none;

value: أس هيدروجيني – Arabic

value:
https://ast.wikipedia.org/wiki/PH
PH – Asturian
ast
ast
interlanguage-link-target

value:
interlanguage-link interwiki-ast
display: none;

value:
interlanguage-link interwiki-bn
display: none;

value:
interlanguage-link interwiki-zh-min-nan
display: none;

value: Вадародны паказчык – Belarusian

value:
interlanguage-link interwiki-be
display: none;

value:
interlanguage-link interwiki-bh
display: none;

value: Водороден показател – Bulgarian

value:
interlanguage-link interwiki-bg
display: none;

value:
https://bs.wikipedia.org/wiki/PH
PH – Bosnian
bs
bs
interlanguage-link-target

value:
interlanguage-link interwiki-bs
display: none;

value:
https://ca.wikipedia.org/wiki/PH
PH – Catalan
ca
ca
interlanguage-link-target

value:
interlanguage-link interwiki-ca
display: none;

value:
https://cs.wikipedia.org/wiki/PH
PH – Czech
cs
cs
interlanguage-link-target

value:
interlanguage-link interwiki-cs
display: none;

value:
https://cy.wikipedia.org/wiki/PH
PH – Welsh
cy
cy
interlanguage-link-target

value:
interlanguage-link interwiki-cy
display: none;

value:
https://da.wikipedia.org/wiki/PH
PH – Danish
da
da
interlanguage-link-target

value:
interlanguage-link interwiki-da
display: none;

value:
https://se.wikipedia.org/wiki/PH
PH – Northern Sami
se
se
interlanguage-link-target

value:
interlanguage-link interwiki-se
display: none;

value:
https://de.wikipedia.org/wiki/PH-Wert
PH-Wert – German
de
de
interlanguage-link-target

value:
interlanguage-link interwiki-de
display: none;

value:
interlanguage-link interwiki-et
display: none;

value: Ενεργός οξύτητα – Greek

value:
interlanguage-link interwiki-el
display: none;

value:
https://es.wikipedia.org/wiki/PH
PH – Spanish
es
es
interlanguage-link-target

value:
interlanguage-link interwiki-eo
display: none;

value:
https://eu.wikipedia.org/wiki/PH
PH – Basque
eu
eu
interlanguage-link-target

value:
interlanguage-link interwiki-eu
display: none;

value:
interlanguage-link interwiki-fa
display: none;

value:
https://ga.wikipedia.org/wiki/PH
PH – Irish
ga
ga
interlanguage-link-target

value:
interlanguage-link interwiki-ga
display: none;

value:
https://gl.wikipedia.org/wiki/PH
PH – Galician
gl
gl
interlanguage-link-target

value:
interlanguage-link interwiki-gl
display: none;

value:
https://hak.wikipedia.org/wiki/PH
PH – Hakka Chinese
hak
hak
interlanguage-link-target

value:
interlanguage-link interwiki-hak
display: none;

value: 수소 이온 농도 – Korean

value:
interlanguage-link interwiki-ko
display: none;

value: Ջրածնային ցուցիչ – Armenian

value:
interlanguage-link interwiki-hy
display: none;

value:
https://hi.wikipedia.org/wiki/PH
PH – Hindi
hi
hi
interlanguage-link-target

value:
https://hr.wikipedia.org/wiki/PH
PH – Croatian
hr
hr
interlanguage-link-target

value:
interlanguage-link interwiki-hr
display: none;

value:
https://io.wikipedia.org/wiki/PH
PH – Ido
io
io
interlanguage-link-target

value:
interlanguage-link interwiki-io
display: none;

value:
https://id.wikipedia.org/wiki/PH
PH – Indonesian
id
id
interlanguage-link-target

value:
interlanguage-link interwiki-ia
display: none;

value:
interlanguage-link interwiki-is
display: none;

value:
https://it.wikipedia.org/wiki/PH
PH – Italian
it
it
interlanguage-link-target

value:
interlanguage-link interwiki-it
display: none;

value:
https://he.wikipedia.org/wiki/PH
PH – Hebrew
he
he
interlanguage-link-target

value:
interlanguage-link interwiki-he
display: none;

value: ಪಿ ಹೆಚ್ – Kannada

value:
interlanguage-link interwiki-kn
display: none;

value:
https://pam.wikipedia.org/wiki/PH
PH – Pampanga
pam
pam
interlanguage-link-target

value:
interlanguage-link interwiki-pam
display: none;

value:
https://kk.wikipedia.org/wiki/PH
PH – Kazakh
kk
kk
interlanguage-link-target

value:
interlanguage-link interwiki-kk
display: none;

value:
interlanguage-link interwiki-sw
display: none;

value:
https://ht.wikipedia.org/wiki/PH
PH – Haitian Creole
ht
ht
interlanguage-link-target

value:
interlanguage-link interwiki-ht
display: none;

value:
https://ku.wikipedia.org/wiki/Nirxa_pH
Nirxa pH – Kurdish
ku
ku
interlanguage-link-target

value:
interlanguage-link interwiki-ku
display: none;

value:
interlanguage-link interwiki-la
display: none;

value:
https://lv.wikipedia.org/wiki/PH
PH – Latvian
lv
lv
interlanguage-link-target

value:
interlanguage-link interwiki-lv
display: none;

value:
interlanguage-link interwiki-lt
display: none;

value:
https://hu.wikipedia.org/wiki/PH
PH – Hungarian
hu
hu
interlanguage-link-target

value:
interlanguage-link interwiki-hu
display: none;

value: Водороден показател – Macedonian

value:
interlanguage-link interwiki-mk
display: none;

value: പി.എച്ച്. മൂല്യം – Malayalam

value:
interlanguage-link interwiki-ml
display: none;

value: पी.एच. मूल्य – Marathi

value:
interlanguage-link interwiki-mr
display: none;

value:
https://ms.wikipedia.org/wiki/PH
PH – Malay
ms
ms
interlanguage-link-target

value:
interlanguage-link interwiki-mn
display: none;

value:
https://my.wikipedia.org/wiki/PH
PH – Burmese
my
my
interlanguage-link-target

value:
interlanguage-link interwiki-my
display: none;

value:
https://nl.wikipedia.org/wiki/PH
PH – Dutch
nl
nl
interlanguage-link-target

value:
interlanguage-link interwiki-nl
display: none;

value: 水素イオン指数 – Japanese

value:
interlanguage-link interwiki-ja
display: none;

value:
interlanguage-link interwiki-frr
display: none;

value:
https://no.wikipedia.org/wiki/PH
PH – Norwegian
no
no
interlanguage-link-target

value:
interlanguage-link interwiki-no
display: none;

value:
https://nn.wikipedia.org/wiki/PH
PH – Norwegian Nynorsk
nn
nn
interlanguage-link-target

value:
interlanguage-link interwiki-nn
display: none;

value:
https://nov.wikipedia.org/wiki/PH
PH – Novial
nov
nov
interlanguage-link-target

value:
interlanguage-link interwiki-nov
display: none;

value:
https://oc.wikipedia.org/wiki/PH
PH – Occitan
oc
oc
interlanguage-link-target

value:
interlanguage-link interwiki-oc
display: none;

value:
https://uz.wikipedia.org/wiki/PH
PH – Uzbek
uz
uz
interlanguage-link-target

value:
interlanguage-link interwiki-uz
display: none;

value: ਪੀ.ਐੱਚ. (ਹਾਈਡਰੋਜਨ ਸ਼ਕਤੀ) – Punjabi

value:
interlanguage-link interwiki-pa
display: none;

value:
interlanguage-link interwiki-pnb
display: none;

value:
https://nds.wikipedia.org/wiki/PH-Weert
PH-Weert – Low German
nds
nds
interlanguage-link-target

value:
interlanguage-link interwiki-nds
display: none;

value:
https://pl.wikipedia.org/wiki/Skala_pH
Skala pH – Polish
pl
pl
interlanguage-link-target

value:
interlanguage-link interwiki-pl
display: none;

value:
https://pt.wikipedia.org/wiki/PH
PH – Portuguese
pt
pt
interlanguage-link-target

value:
https://ro.wikipedia.org/wiki/PH
PH – Romanian
ro
ro
interlanguage-link-target

value:
interlanguage-link interwiki-ro
display: none;

value: Водородный показатель – Russian

value:
https://sco.wikipedia.org/wiki/PH
PH – Scots
sco
sco
interlanguage-link-target

value:
interlanguage-link interwiki-sco
display: none;

value:
https://sq.wikipedia.org/wiki/PH
PH – Albanian
sq
sq
interlanguage-link-target

value:
interlanguage-link interwiki-sq
display: none;

value:
https://scn.wikipedia.org/wiki/PH
PH – Sicilian
scn
scn
interlanguage-link-target

value:
interlanguage-link interwiki-scn
display: none;

value:
https://simple.wikipedia.org/wiki/PH
PH – Simple English
simple
simple
interlanguage-link-target

value:
interlanguage-link interwiki-simple
display: none;

value:
interlanguage-link interwiki-sk
display: none;

value:
https://sl.wikipedia.org/wiki/PH
PH – Slovenian
sl
sl
interlanguage-link-target

value:
interlanguage-link interwiki-sl
display: none;

value:
https://so.wikipedia.org/wiki/PH
PH – Somali
so
so
interlanguage-link-target

value:
interlanguage-link interwiki-so
display: none;

value:
interlanguage-link interwiki-ckb
display: none;

value: PH вредност – Serbian

value:
interlanguage-link interwiki-sr
display: none;

value:
interlanguage-link interwiki-sh
display: none;

value:
https://su.wikipedia.org/wiki/PH
PH – Sundanese
su
su
interlanguage-link-target

value:
interlanguage-link interwiki-su
display: none;

value:
https://fi.wikipedia.org/wiki/Happamuus
Happamuus – Finnish
fi
fi
interlanguage-link-target

value:
interlanguage-link interwiki-fi
display: none;

value:
https://sv.wikipedia.org/wiki/PH
PH – Swedish
sv
sv
interlanguage-link-target

value:
interlanguage-link interwiki-sv
display: none;

value:
https://tl.wikipedia.org/wiki/PH
PH – Tagalog
tl
tl
interlanguage-link-target

value:
interlanguage-link interwiki-tl
display: none;

value: காரகாடித்தன்மைச் சுட்டெண் – Tamil

value:
interlanguage-link interwiki-ta
display: none;

value:
https://te.wikipedia.org/wiki/PH
PH – Telugu
te
te
interlanguage-link-target

value:
interlanguage-link interwiki-te
display: none;

value: พีเอช (เคมี) – Thai

value:
interlanguage-link interwiki-th
display: none;

value:
https://tr.wikipedia.org/wiki/PH
PH – Turkish
tr
tr
interlanguage-link-target

value:
interlanguage-link interwiki-tr
display: none;

value:
https://uk.wikipedia.org/wiki/PH
PH – Ukrainian
uk
uk
interlanguage-link-target

value:
interlanguage-link interwiki-uk
display: none;

value:
https://vi.wikipedia.org/wiki/PH
PH – Vietnamese
vi
vi
interlanguage-link-target

value:
interlanguage-link interwiki-vi
display: none;

value:
https://vls.wikipedia.org/wiki/PH
PH – West Flemish
vls
vls
interlanguage-link-target

value:
interlanguage-link interwiki-vls
display: none;

value:
https://war.wikipedia.org/wiki/PH
PH – Waray
war
war
interlanguage-link-target

value:
interlanguage-link interwiki-war
display: none;

value:
interlanguage-link interwiki-zh-yue
display: none;

value:
https://kbp.wikipedia.org/wiki/PH
PH – Kabiye
kbp
kbp
interlanguage-link-target

value:
interlanguage-link interwiki-kbp
display: none;

value: All languages (initial selection from common choices by you and others)

value: /static/images/wikimedia-button-1.5x.png 1.5x, /static/images/wikimedia-button-2x.png 2x

value: /static/images/poweredby_mediawiki_132x47.png 1.5x, /static/images/poweredby_mediawiki_176x62.png 2x

value:
suggestions
display: none; font-size: 13px;

value: mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-PH rootpage-PH skin-vector action-view