What Gas is Formed When a Carbonate Reacts with an Acid?

When a carbonate reacts with an acid, the gas formed is carbon dioxide (CO₂).

Here’s the explanation:

Carbonates are compounds that contain the carbonate ion (CO₃^2-). When a carbonate reacts with an acid, a chemical reaction occurs that produces carbon dioxide gas, water, and a salt. The general equation for this reaction is:

Carbonate + Acid → Salt + Water + Carbon Dioxide

For example, when calcium carbonate (CaCO₃) reacts with hydrochloric acid (HCl), the reaction produces calcium chloride (CaCl₂), water (H₂O), and carbon dioxide (CO₂):

CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

This reaction is commonly observed in everyday life, such as when vinegar (an acid) is poured on baking soda (a carbonate), resulting in the fizzing due to the release of carbon dioxide gas.