Acid

acidicacidityacidsdiproticdibasicdiprotic acidmonoprotic acidpolyprotic acidprotic acidfree acid
An acid is a molecule or ion capable of donating a proton (hydrogen ion H + ), or, alternatively, capable of forming a covalent bond with an electron pair (a Lewis acid).wikipedia
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Acid–base reaction

acid-base reactionacid-baseacid-base chemistry
In the special case of aqueous solutions, proton donors form the hydronium ion H 3 O + and are known as Arrhenius acids.
An acid–base reaction is a chemical reaction that occurs between an acid and a base.

PH

pH levelneutralpH value
An aqueous solution of an acid has a pH less than 7 and is colloquially also referred to as 'acid' (as in 'dissolved in acid'), while the strict definition refers only to the solute.
In chemistry, pH is a scale used to specify how acidic or basic a water-based solution is.

Base (chemistry)

basebasicbases
Acids form aqueous solutions with a sour taste, can turn blue litmus red, and react with bases and certain metals (like calcium) to form salts. An Arrhenius base, on the other hand, is a substance which increases the concentration of hydroxide (OH − ) ions when dissolved in water.
In chemistry, bases are substances that, in aqueous solution, release hydroxide (OH − ) ions, are slippery to the touch, can taste bitter if an alkali, change the color of indicators (e.g., turn red litmus paper blue), react with acids to form salts, promote certain chemical reactions (base catalysis), accept protons from any proton donor or contain completely or partially displaceable OH − ions.

Salt (chemistry)

saltsaltspotassium salt
Acids form aqueous solutions with a sour taste, can turn blue litmus red, and react with bases and certain metals (like calcium) to form salts.
Salts that produce acidic solutions are acid salts.

Corrosive substance

corrosivecausticcaustics
Strong acids and some concentrated weak acids are corrosive, but there are exceptions such as carboranes and boric acid.
They can be acids, oxidizers, or bases.

Hydrochloric acid

HClhydrochloricmuriatic acid
Common aqueous acids include hydrochloric acid (a solution of hydrogen chloride which is found in gastric acid in the stomach and activates digestive enzymes), acetic acid (vinegar is a dilute aqueous solution of this liquid), sulfuric acid (used in car batteries), and citric acid (found in citrus fruits). Examples of strong acids are hydrochloric acid (HCl), hydroiodic acid (HI), hydrobromic acid (HBr), perchloric acid (HClO 4 ), nitric acid (HNO 3 ) and sulfuric acid (H 2 SO 4 ). Common examples of monoprotic acids in mineral acids include hydrochloric acid (HCl) and nitric acid (HNO 3 ).
Hydrochloric acid is also known as hydronium chloride, in contrast to its anhydrous parent known as hydrogen chloride, or dry HCl.

Litmus

litmus paperlitmus testLitmus test (chemistry)
Acids form aqueous solutions with a sour taste, can turn blue litmus red, and react with bases and certain metals (like calcium) to form salts.
It is often adsorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity.

Acetic acid

aceticglacial acetic acidacetate
Common aqueous acids include hydrochloric acid (a solution of hydrogen chloride which is found in gastric acid in the stomach and activates digestive enzymes), acetic acid (vinegar is a dilute aqueous solution of this liquid), sulfuric acid (used in car batteries), and citric acid (found in citrus fruits). Consider the following reactions of acetic acid (CH 3 COOH), the organic acid that gives vinegar its characteristic taste:
The name acetic acid derives from acetum, the Latin word for vinegar, and is related to the word acid itself.

Hydroxide

OHhydroxide ionOH −
An Arrhenius base, on the other hand, is a substance which increases the concentration of hydroxide (OH − ) ions when dissolved in water.
A hydroxide attached to a strongly electropositive center may itself ionize, liberating a hydrogen cation (H + ), making the parent compound an acid.

Acid dissociation constant

p''K'' a pKapK a
The acid dissociation constant K a is generally used in the context of acid-base reactions.
An acid dissociation constant, K a, (also known as acidity constant, or acid-ionization constant) is a quantitative measure of the strength of an acid in solution.

Ammonia

NH 3 anhydrous ammonialiquid ammonia
An example is boron trifluoride (BF 3 ), whose boron atom has a vacant orbital which can form a covalent bond by sharing a lone pair of electrons on an atom in a base, for example the nitrogen atom in ammonia (NH 3 ).
It combines with acids to form salts; thus with hydrochloric acid it forms ammonium chloride (sal ammoniac); with nitric acid, ammonium nitrate, etc. Perfectly dry ammonia will not combine with perfectly dry hydrogen chloride; moisture is necessary to bring about the reaction.

Aqueous solution

aqueouswater solubilityaqueous solutions
In the special case of aqueous solutions, proton donors form the hydronium ion H 3 O + and are known as Arrhenius acids. Acids form aqueous solutions with a sour taste, can turn blue litmus red, and react with bases and certain metals (like calcium) to form salts.
Acids and bases are aqueous solutions, as part of their Arrhenius definitions.

Hypochlorous acid

HOClHClOhypochlorite
Hypochlorous acid (HOCl) is a weak acid that forms when chlorine dissolves in water, and itself partially dissociates, forming hypochlorite, ClO −.

Conjugate acid

conjugate baseconjugateconjugate bases
Reactions of acids are often generalized in the form HA H + + A −, where HA represents the acid and A − is the conjugate base.
Because some acids are capable of releasing multiple protons, the conjugate base of an acid may itself be acidic.

Acid strength

weak acidstrong acidstrong acids
Strong acids and some concentrated weak acids are corrosive, but there are exceptions such as carboranes and boric acid. Examples of strong acids are hydrochloric acid (HCl), hydroiodic acid (HI), hydrobromic acid (HBr), perchloric acid (HClO 4 ), nitric acid (HNO 3 ) and sulfuric acid (H 2 SO 4 ).
Acid strength refers to the tendency of an acid, symbolised by the chemical formula HA, to dissociate into a proton, H +, and an anion, A −.

Sulfuric acid

sulphuric acidsulfuricH 2 SO 4
Common aqueous acids include hydrochloric acid (a solution of hydrogen chloride which is found in gastric acid in the stomach and activates digestive enzymes), acetic acid (vinegar is a dilute aqueous solution of this liquid), sulfuric acid (used in car batteries), and citric acid (found in citrus fruits). Examples of strong acids are hydrochloric acid (HCl), hydroiodic acid (HI), hydrobromic acid (HBr), perchloric acid (HClO 4 ), nitric acid (HNO 3 ) and sulfuric acid (H 2 SO 4 ).
Dilute sulfuric acid reacts with metals via a single displacement reaction as with other typical acids, producing hydrogen gas and salts (the metal sulfate).

Hydroiodic acid

hydriodic acidHIhydroiodic
Examples of strong acids are hydrochloric acid (HCl), hydroiodic acid (HI), hydrobromic acid (HBr), perchloric acid (HClO 4 ), nitric acid (HNO 3 ) and sulfuric acid (H 2 SO 4 ).
Hydroiodic acid (or hydriodic acid) is a highly acidic aqueous solution of hydrogen iodide (HI)

Superacid

superacidssuper acid
Superacids are acids stronger than 100% sulfuric acid.
According to the classical definition, a superacid is an acid with an acidity greater than that of 100% pure sulfuric acid, which has a Hammett acidity function (H 0 ) of −12.

Hydrobromic acid

HBrhydrobromichydrobromide
Examples of strong acids are hydrochloric acid (HCl), hydroiodic acid (HI), hydrobromic acid (HBr), perchloric acid (HClO 4 ), nitric acid (HNO 3 ) and sulfuric acid (H 2 SO 4 ).
Hydrobromic acid is a strong acid formed by dissolving the diatomic molecule hydrogen bromide (HBr) in water.

Svante Arrhenius

Svante August ArrheniusArrheniusArrhenius, Svante August
The Swedish chemist Svante Arrhenius attributed the properties of acidity to hydrogen ions (H + ) or protons in 1884.
In an extension of his ionic theory Arrhenius proposed definitions for acids and bases, in 1884.

Hydron (chemistry)

H + hydronproton
The Swedish chemist Svante Arrhenius attributed the properties of acidity to hydrogen ions (H + ) or protons in 1884. A lower pH means a higher acidity, and thus a higher concentration of positive hydrogen ions in the solution.
The hydrated form of the hydrogen cation, the hydronium (hydroxonium) ion (aq), is a key object of Arrhenius' definition of acid.

Organic acid

organic acidsorganicacid
Consider the following reactions of acetic acid (CH 3 COOH), the organic acid that gives vinegar its characteristic taste:
An organic acid is an organic compound with acidic properties.

Mineral acid

mineral acidsinorganic acidmineral
Common examples of monoprotic acids in mineral acids include hydrochloric acid (HCl) and nitric acid (HNO 3 ).
A mineral acid (or inorganic acid) is an acid derived from one or more inorganic compounds.

Nitric acid

nitricHNO 3 aqua fortis
Examples of strong acids are hydrochloric acid (HCl), hydroiodic acid (HI), hydrobromic acid (HBr), perchloric acid (HClO 4 ), nitric acid (HNO 3 ) and sulfuric acid (H 2 SO 4 ). Common examples of monoprotic acids in mineral acids include hydrochloric acid (HCl) and nitric acid (HNO 3 ).
Dilute nitric acid behaves as a typical acid in its reaction with most metals.

Dissociation (chemistry)

dissociationdissociatedissociates
Monoprotic acids, also known as monobasic acids, are those acids that are able to donate one proton per molecule during the process of dissociation (sometimes called ionization) as shown below (symbolized by HA):
For instance, when an acid dissolves in water, a covalent bond between an electronegative atom and a hydrogen atom is broken by heterolytic fission, which gives a proton (H + ) and a negative ion.