kinetix

yup pls explain in detail (just started chemical kinetix)

Acid dissociation constant
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Acetic acid, CH3COOH, is composed of a methyl group, CH3, bound chemically to a carboxylate group, COOH. The carboxylate group can lose a proton and donate it to a water molecule, H20, leaving behind an acetate anion CH3COO- and creating a hydronium cation H3O . This is an equilibrium reaction, so the reverse process can also take place.
Acetic acid, a weak acid, donates a proton (hydrogen ion, green) to water in an equilibrium reaction to give the acetate ion and the hydronium ion. Red: oxygen, black: carbon, white: hydrogen.

An acid dissociation constant, Ka, (also known as acidity constant, or acid-ionization constant) is a quantitative measure of the strength of an acid in solution. It is the equilibrium constant for a chemical reaction known as dissociation in the context of acid-base reactions. The equilibrium can be written symbolically as:

HA is in equilibrium with A− + H+,

where HA is a generic acid which dissociates by splitting into A−, known as the conjugate base of the acid, and the hydrogen ion or proton, H+, which, in the case of aqueous solutions, exists as a solvated hydronium ion. In the example shown in the figure, HA represents acetic acid, and A− the acetate ion. The chemical species HA, A− and H+ are said to be in equilibrium when their concentrations do not change with the passing of time. The dissociation constant is usually written as a quotient of the equilibrium concentrations, denoted by [HA], [A−] and [H+]:

K_a equals the equilibrium concentration of the deprotonated form A-, times the equilibrium concentration of H+, all divided by the equilibrium concentration of the acid AH.

or see this

http://en.wikipedia.org/wiki/Ionization_constant

thanx msp!

yeah thx sankara