What is the chemical formula for acid?

Answer 1

If it is inorganic acid then the acid needs to have at least one H+ donor or electron acceptor, like HCl which gives H+ and Cl- .

If it is organic then it is RCOOH where R can be any organic compound for e.g. CH3COOH which is methanoic acid a weak acid. (Note: all organic acids are weak acids.)

Answer 2

Formula: H+Xn-

Where X is the conjugate base of the acid