When carbonates react with acids, they produce a salt, water, and carbon dioxide gas.

This reaction is classified as an acid-base reaction, in which the carbonate acts as a base and the acid provides hydrogen ions. Specifically, the carbonate ion ($\text{CO}_3^{2-}$) reacts with hydrogen ions ($\text{H}^+$) from the acid to form water ($\text{H}_2\text{O}$) and carbon dioxide ($\text{CO}_2$). This reaction is observable as bubbling or fizzing, which is the visible release of carbon dioxide gas.

Additionally, the reaction yields a salt. The particular type of salt formed depends on the specific acid and carbonate involved. For instance, when hydrochloric acid ($\text{HCl}$) reacts with sodium carbonate ($\text{Na}_2\text{CO}_3$), the products are sodium chloride ($\text{NaCl}$), which is common table salt, along with water and carbon dioxide.

The general equation for this reaction can be represented as:

Understanding this reaction is crucial in GCSE Chemistry, as it exemplifies a gas-forming reaction. It also serves as a practical method for generating carbon dioxide in laboratory settings. Furthermore, this process plays a significant role in the natural carbon cycle, where carbonates in rocks react with acids present in rainwater, releasing carbon dioxide into the atmosphere.

When conducting these reactions in a laboratory, safety is paramount. Always wear safety goggles and adhere to your teacher’s instructions for a safe experiment.