Carboxyl group ($-\mathrm{C}(=\mathrm{O})\mathrm{OH}$)

A carboxyl group is the functional group $-\mathrm{C}(=\mathrm{O})\mathrm{OH}$: one carbon has a double bond to oxygen and a single bond to a hydroxyl group. It gives a carboxylic acid its characteristic acid functionality. In acetic acid, the group is attached to a methyl group, giving $\mathrm{C}{\mathrm{H}}_3\mathrm{COOH}$.^[ref]

Loss of the acidic hydrogen produces a carboxylate, the conjugate base:The pH influences the balance between these forms. A structural drawing of the neutral acid therefore need not show the predominant charge state in every solution. The carboxyl group is a part of the molecule, while acetic acid names the entire compound.