When an acid reacts with a carbonate, the three products are:

1. Salt: This is formed from the cation of the carbonate and the anion of the acid. For example, if you react hydrochloric acid (HCl) with calcium carbonate (CaCO3), the salt formed is calcium chloride (CaCl2).

2. Water: This is formed from the hydrogen ions (H+) from the acid and the hydroxide ions (OH-) from the carbonate.

3. Carbon dioxide (CO2): This is released as a gas.

Here's a general equation for the reaction:

Acid + Carbonate → Salt + Water + Carbon Dioxide

Example:

HCl (acid) + CaCO3 (carbonate) → CaCl2 (salt) + H2O (water) + CO2 (carbon dioxide)