Acetate

 The acetate anion (IUPC name ethanoate ion) is the conjugate base of the dissociation of ethanoic acid. As ethanoic acid is a weak acid it sets up an equilibrium in an aqueous solution. The acetate ions can only be found in small quantities in this equilibrium, which is as follows:

CH3COOH ⇌ CH3COO— + H+

Acetate ions are anions and so will form ionic complexes with cations such as sodium ethanoate an important compound used in acidic buffers.