Acetate, also known as ethanoate, is the salt or ester of acetic acid (vinegar). It is also an ion of acetic acid. It is formed when acetic acid dissolves in water (which splits into an acetate anion and a hydron). The chemical formula is CH₃COO⁻ (also written as CH₃CO−2 or C₂H₃O−2) when it exists as an ion. Acetate salts turn brown when heated, and smell like acetic acid.

Acetate esters have the chemical formula CH₃COOR (where R is an organic group like an alkyl or aryl group). It is made when acetic acid reacts with an alcohol to make an acetic ester and water.

The reaction between acetic acid and ethanol gives ethyl acetate and water:

CH₃COOH + CH₃OH ⇌ CH₃COOC₂H₅ + H₂O

Acetate salts are made when acetic acid reacts with a base (like sodium hydroxide).

The reaction between acetic acid and sodium hydroxide gives sodium acetate and water:

CH₃COOH + NaOH —> CH₃COONa + H₂O

• methyl acetate: CH₃COOCH₃
• ethyl acetate: CH₃COOC₂H₅
• sodium acetate: CH₃COONa
• potassium acetate: CH₃COOK

• Protonation
• Acid
• Formate
• Carboxylate
• Carboxylic acid