acid salt

An acid salt is a salt of an acid that has two or more replaceable hydrogen atoms in which not all of the hydrogens are replaced by a metal or its equivalent. For example, the dibasic acid carbonic acid (H2CO3) forms acid salts such as sodium hydrogen carbonate (sodium bicarbonate, NaHCO3). The tribasic acid phosphoric (V) acid (orthophosphoric acid, H3PO4) forms two series of acid salts, such as sodium dihydrogen phosphate (NaH2PO4) and disodium hydrogen phosphate (Na2HPO4).