WordNet

any of various water-soluble compounds capable of turning litmus blue and reacting with an acid to form a salt and water; "bases include oxides and hydroxides of metals and ammonia" (同)alkali
(numeration system) the positive integer that is equivalent to one in the next higher counting place; "10 is the radix of the decimal system" (同)radix
the bottom side of a geometric figure from which the altitude can be constructed; "the base of the triangle"
situate as a center of operations; "we will base this project in the new lab"
a place that the runner must touch before scoring; "he scrambled to get back to the bag" (同)bag
installation from which a military force initiates operations; "the attack wiped out our forward bases" (同)base of operations
a support or foundation; "the base of the lamp" (同)pedestal, stand
(electronics) the part of a transistor that separates the emitter from the collector
a flat bottom on which something is intended to sit; "a tub should sit on its own base"
the principal ingredient of a mixture; "glycerinated gelatin is used as a base for many ointments"; "he told the painter that he wanted a yellow base with just a hint of green"; "everything she cooked seemed to have rice as the base"
the place where you are stationed and from which missions start and end (同)home
(anatomy) the part of an organ nearest its point of attachment; "the base of the skull"
the bottom or lowest part; "the base of the mountain"
illegitimate (同)baseborn
of low birth or station (`base is archaic in this sense); "baseborn wretches with dirty faces"; "of humble (or lowly) birth" (同)baseborn, humble, lowly
not adhering to ethical or moral principles; "base and unpatriotic motives"; "a base, degrading way of life"; "cheating is dishonorable"; "they considered colonialism immoral"; "unethical practices in handling public funds" (同)immoral
having or showing an ignoble lack of honor or morality; "that liberal obedience without which your army would be a base rabble"- Edmund Burke; "taking a mean advantage"; "chokd with ambition of the meaner sort"- Shakespeare; "something essentially vulgar and meanspirited in politics" (同)mean, meanspirited
(used of metals) consisting of or alloyed with inferior metal; "base coins of aluminum"; "a base metal"
debased; not genuine; "an attempt to eliminate the base coinage"
undergo conjugation
unite chemically so that the product is easily broken down into the original compounds
formed by the union of two compounds; "a conjugated protein" (同)conjugated
of an organic compound; containing two or more double bonds each separated from the other by a single bond (同)conjugated
joined together especially in a pair or pairs (同)conjugated, coupled
(of a pinnate leaflet) having only one pair of leaflets
add inflections showing person, number, gender, tense, aspect, etc.; "conjugate the verb"
having a base; "firmly based ice"
having a base of operations (often used as a combining form); "a locally based business"; "an Atlanta-based company"; "carrier-based planes"

PrepTutorEJDIC

《文》(人や人の行動・孝えが)『卑しい』,下劣な / (金属が)質の劣った;(貨幣が)粗悪な
『基礎』,根拠 / 『基部』,基底,土台 / 『根拠地』,基地 / (野球の)塁,ベース / 主成分;塩基(酸と反応シテ塩(官)を生じる化合物) / (数学で図形の)底;底辺;基線 / (…に)…‘の'『基礎をおく』《+『名』+『on』(『upon』)+『名』》
〈動詞〉'を'活用(変化)させる / 〈動詞が〉活用(変化)する / 〈単細胞生物が〉接合する / (特に対になって)結合した,接合の
basisの複数形

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/09/24 03:09:56」(JST)

wiki en

A conjugate acid, within the Brønsted–Lowry acid–base theory, is a species formed by the reception of a proton (H⁺), by a base—in other words, the base with a hydrogen ion added to it. On the other hand, a conjugate base is merely what is left after an acid has donated a proton in a chemical reaction. Hence, a conjugate base is a species formed by the removal of a proton from an acid.^[1]

In summary, this can be represented as the following chemical reaction:

Acid + Base Conjugate Base + Conjugate Acid

Johannes Nicolaus Brønsted (left) and Martin Lowry (right).

Johannes Nicolaus Brønsted and Martin Lowry introduced the Brønsted–Lowry theory, which proposed that any compound that can transfer a proton to any other compound is an acid, and the compound that accepts the proton is a base. A proton is a nuclear particle with a unit positive electrical charge; it is represented by the symbol H⁺ because it constitutes the nucleus of a hydrogen atom.^[2]

Acid-base reactions

In an acid-base reaction, an acid plus a base reacts to form a conjugate base plus a conjugate acid:

Conjugates are formed when an acid loses a hydrogen proton or a base gains a hydrogen proton. Refer to the following figure:

We say that the water molecule is the conjugate acid of the hydroxide ion after the latter received the hydrogen proton donated by ammonium. On the other hand, ammonia is the conjugate base for the acid ammonium after ammonium has donated a hydrogen ion towards the production of the water molecule. We can also refer to OH- as a conjugate base of H
2O, since the water molecule donates a proton towards the production of NH+
4 in the reverse reaction, which is the predominating process in nature due to the strength of the base NH
3 over the hydroxide ion. Based on this information, it is clear that the terms "Acid", "Base", "conjugate acid", and "conjugate base" are not fixed for a certain chemical species; but are interchangeable according to the reaction taking place.

Strength of conjugates

The strength of a conjugate acid is directly proportional to its dissociation constant. If a conjugate acid is strong, its dissociation will have a higher equilibrium constant and the products of the reaction will be favored. The strength of a conjugate base can be seen as the tendency of the species to "pull" hydrogen protons towards itself. If a conjugate base is classified as strong, it will "hold on" to the hydrogen proton when in solution and its acid will not dissociate.

If a chemical species is classified as a weak acid, its conjugate base will be strong in nature. This can be observed in ammonia's (relatively strong base) reaction with water. The reaction proceeds until most of the ammonia has been transformed to ammonium. This shift to the right in the chemical equilibrium of the reaction means that ammonium does not dissociate easily in water (weak acid), and its conjugate base is stronger than the hydroxide ion.

On the other hand, if a species is classified as a strong acid, its conjugate base will be weak in nature. An example of this case would be the dissociation of Hydrochloric acid HCl in water. Since HCl is a strong acid (it dissociates to a great extent), its conjugate base (Cl^-) will be a weak conjugate base. Therefore, in this system, most H+ will be in the form of a Hydronium ion H
3O⁺ instead of attached to a Cl anion and the conjugate base will be weaker than a water molecule.

To summarize, the stronger the acid or base, the weaker the conjugate and vice versa.

Identifying conjugate acid-base pairs

The acid and conjugate base as well as the base and conjugate acid are known as conjugate pairs. When finding a conjugate acid or base, it is important to look at the reactants of the chemical equation. In this case, the reactants are the acids and bases, and the acid corresponds to the conjugate base on the product side of the chemical equation; as does the base to the conjugate acid on the product side of the equation.

To identify the conjugate acid, look for the pair of compounds that are related. The acid-base reaction can be viewed in a before and after sense. The before is the reactant side of the equation, the after is the product side of the equation. The conjugate acid in the after side of an equation gains a hydrogen ion, so in the before side of the equation the compound that has one less hydrogen ion of the conjugate acid is the base. The conjugate base in the after side of the equation lost a hydrogen ion, so in the before side of the equation the compound that has one more hydrogen ion of the conjugate base is the acid.

Consider the following acid-base reaction:

HNO
3 + H
2O → H
3O+
+ NO−
3

Nitric acid (HNO
3) is an acid because it donates a proton to the water molecule and its conjugate base is nitrate (NO−
3). The water molecule acts as a base because it receives the Hydrogen Proton and its conjugate acid is the hydronium ion (H
3O+
).

Equation	Acid	Base	Conjugate Base	Conjugate Acid
HClO 2 + H 2O → ClO− 2 + H 3O+	HClO 2	H 2O	ClO− 2	H 3O+
ClO− + H 2O → HClO + OH−	H 2O	ClO−	OH−	HClO
HCl + H 2PO− 4 → Cl− + H 3PO 4	HCl	H 2PO− 4	Cl−	H 3PO 4

Applications

One use of conjugate acids and bases lies in buffering systems, which include a buffer solution. In a buffer, a weak acid and its conjugate base (in the form of a salt), or a weak base and its conjugate acid are used in order to limit the pH change during a titration process. Buffers have both organic and non-organic chemical applications; for instance, besides buffers being used in lab processes, our blood acts as a buffer to maintain pH. The most important buffer in our bloodstream is the carbonic acid-bicarbonate buffer, which prevents drastic pH changes when CO
2 is introduced. This functions as such:

Furthermore, here is a table of common buffers.

Buffering agent	pK_a	useful pH range
Citric acid	3.13, 4.76, 6.40	2.1 - 7.4
Acetic acid	4.8	3.8 - 5.8
KH₂PO₄,	7.2	6.2 - 8.2
CHES	9.3	8.3–10.3
Borate	9.24	8.25 - 10.25

A second common application with an organic compound would be the production of a buffer with acetic acid. If acetic acid, a weak acid with the formula CH
3COOH, was made into a buffer solution, it would need to be combined with its conjugate base CH
3COO−
in the form of a salt. The resulting mixture is called an acetate buffer, consisting of aqueous CH
3COOH and aqueous CH
3COONa. Acetic acid, along with many other weak acids, serve as useful components of buffers in different lab settings, each useful within their own pH range.

An example with an inorganic compound would be the medicinal use of lactic acid’s conjugate base known as lactate in Lactated Ringer's solution and Hartmann's solution. Lactic acid has the formula C
3H
6O
6 and its conjugate base is used in intravenous fluids that consist of sodium and potassium cations along with lactate and chloride anions in solution with distilled water. These fluids are commonly isotonic in relation to human blood and are commonly used for spiking up the fluid level in a system after severe blood loss due to trauma, surgery, or burn injury.

Table of acids and their conjugate bases

Tabulated below are several examples of acids and their conjugate bases; notice how they differ by just one proton (H⁺ ion). Acid strength decreases and conjugate base strength increases down the table.

Acid	Conjugate Base
H 2F+ Fluoronium ion	HF Hydrogen fluoride
HCl Hydrochloric acid	Cl⁻ Chloride ion
H₂SO₄ Sulfuric acid	HSO₄⁻ Hydrogen sulfate ion
HNO₃ Nitric acid	NO₃⁻ Nitrate ion
H₃O⁺ Hydronium ion	H₂O Water
HSO₄⁻ Hydrogen sulfate ion	SO₄²⁻ Sulfate ion
H₃PO₄ Phosphoric acid	H₂PO₄⁻ Dihydrogen phosphate ion
CH₃COOH Acetic acid	CH₃COO⁻ Acetate ion
H₂CO₃ Carbonic acid	HCO₃⁻ Hydrogen carbonate ion
H₂S Hydrosulfuric acid	HS⁻ Hydrogen sulfide ion
H₂PO₄⁻ Dihydrogen phosphate ion	HPO₄²⁻ Hydrogen phosphate ion
NH₄⁺ Ammonium ion	NH₃ Ammonia
HCO₃⁻ Hydrogencarbonate (bicarbonate) ion	CO₃²⁻ Carbonate ion
HPO₄²⁻ Hydrogen phosphate ion	PO₄³⁻ Phosphate ion
H₂O Water (neutral, pH 7)	OH⁻ Hydroxide ion

Table of bases and their conjugate acids

In contrast, here is a table of bases and their conjugate acids. Similarly, base strength decreases and conjugate acid strength increases down the table.

Base	Conjugate Acid
C 2H 5NH 2 Ethylamine	C 2H 5NH+ 3 Ethylammonium ion
CH 3NH 2 Methylamine	CH 3NH+ 3 Methylammonium ion
NH 3 Ammonia	NH+ 4 Ammonium ion
C 5H 5N Pyridine	C 5H 6N+ Pyridinium
C 6H 5NH 2 Aniline	C 6H 5NH+ 3 Phenylammonium ion
C 6H 5CO− 2 Benzoate ion	C 6H 6CO 2 Benzoic acid
F− Fluoride ion	HF Hydrogen fluoride

References

^ Zumdahl, Stephen S., & Zumdahl, Susan A. Chemistry. Houghton Mifflin, 2007, ISBN 0618713700
^ "Bronsted-Lowry theory". Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2015. Web. 21 Apr. 2015 <http://www.britannica.com/EBchecked/topic/80953/Bronsted-Lowry-theory>.

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 胎児の酸塩基の生理学 fetal acid base physiology
2. 臍帯血酸塩基分析 umbilical cord blood acid base analysis
3. インフルエンザ菌感染の予防 prevention of haemophilus influenzae infection
4. 髄膜炎菌ワクチン meningococcal vaccines
5. 単純性および混合性酸塩基障害 simple and mixed acid base disorders

English Journal

Self-decarboxylation of trichloroacetic acid redox catalyzed by trichloroacetate ions in acetonitrile solutions.

Valencia DP, Astudillo PD, Galano A, González FJ.SourceDepartamento de Química del Centro de Investigación y de Estudios Avanzados del I.P.N., Av. IPN 2508, Col. San Pedro Zacatenco, 07360, Distrito Federal, Mexico. fgonzale@cinvestav.mx.
Organic & biomolecular chemistry.Org Biomol Chem.2013 Jan 14;11(2):318-25. doi: 10.1039/c2ob26961a. Epub 2012 Nov 19.
In mixtures of trichloroacetate ion and trichloroacetic acid in acetonitrile, trichloromethyl radicals are produced as a result of the redox reaction between the acid and its conjugate base. The reaction follows a loop mechanism in which the trichloroacetic acid is slowly consumed by proton reductio
PMID 23165440

Japanese Journal

遷移金属錯体の酸・塩基作用を利用する触媒的不斉反応の開発

濱島義隆,袖岡幹子
有機合成化学協会誌 69(9), 972-984, 2011-09-01
… Acid-base catalysis of chiral transition metal complexes having hard anionic ligands such as hydroxo and acetate ligands is described. … For efficient activation of less acidic α-ketoesters, we developed a novel chiral nickel acetate complex, which is particularly effective to promote the asymmetric conjugate addition to nitroolefins. …
NAID 10029617805

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関連記事	「conjugate」「base」「conjugated」

「conjugate」

　　[★]

n.

抱合体、接合体、複合物

vt.

(言語)(動詞)を活用/変化させる。
(化学)～を共役させる。

vi.

(生物)接合する。(言語)動詞が活用/変化する。
抱合する、接合する、結合する、共役する

adj.

関: associate、bind、binding、bond、bonding、combine、complex、conjoin、conjugated、conjugation、conjunction、connect、connection、couple、coupling、dock、engage、engagement、join、juncture、ligate、linkage、mating、symphysial、union、zygote、zygotic

「base」

　　[★]

n.

基礎、基盤、根拠、基本、基底

関: basal、base、basement、basic、basis、element、elementary、evidence、foundation、fundamental、fundamentals、fundus、ground、infrastructure、reason

「conjugated」

　　[★]

adj.

抱合型の、複合化の、(化学)共役した

関: conjugate、conjugation、couple、coupling

[1] Zumdahl, Stephen S., & Zumdahl, Susan A. Chemistry. Houghton Mifflin, 2007, ISBN 0618713700

[2] "Bronsted-Lowry theory". Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2015. Web. 21 Apr. 2015 <http://www.britannica.com/EBchecked/topic/80953/Bronsted-Lowry-theory>.

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案内

conjugate base