Acid
An acid (from Latin acidus, meaning sour or tart) is a chemical compound generally defined by its reactions with complementary chemicals, designated bases (see Acid-base reaction theories). An acid tends to give a proton and can be represented by the generic formula AH. In water, there is the following reaction:
There is a distinction between weak acids and strong acids. For a strong acid, no AH remains in solution:
That is why the acidity constant is only defined for weak acids:
Some of the stronger acids include the hydrohalic acids - HCl, HBr, and HI - and the oxyacids, which tend to contain central atoms in high oxidation states surrounded by oxygen - including HNO3, H2SO4, HClO4.
Acidity is typically measured using the pH scale.
Acidic (chemistry), the opposite to basic, reacting with basics to form salts.
Acidic (geology), of rock: containing more than 65% of silica.
Acids are generally:
The word acid comes from the Latin acidus meaning sour. Chemically though the term acid has a more specific meaning.
The Swedish chemist Svante Arrhenius defined an acid to be a substance that gave up hydrogen ions (H+) when dissolved in water, while bases are substances that give up hydroxide ions (OH-). Notice that this definition limits acids and bases to substances that can dissolve in water. Later on, Bronsted[?] and Lowry[?] defined an acid to be a proton donor and a base to be a proton acceptor. In this definition, even substances that are insoluble in water can be acids and bases. The most general definition of acids and bases is the Lewis definition. A Lewis acid is an electron acceptor, while a Lewis base[?] is an electron donor. Acid/base systems are different from redox reactions in that there is no change in oxidation state.
Table of contents
1 Characteristics
2 Acids in Food
3 Different Definitions of Acid/Base
4 Other meanings
Characteristics
Acids in Food
Different Definitions of Acid/Base
Other meanings