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Why does acid react with chalk to produce carbon dioxide bubbles?

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sodium sulfate — acid–base reaction Sodium sulfate, also called Glauber's salt, is, like other salts, the product of an acid-base reaction.

Chalk is primarily composed of calcium carbonate ( $C a C O_{3}$ ), a base that reacts with acids in a gas-forming reaction.

When an acid (such as hydrochloric acid) is applied to chalk, the two substances undergo a chemical process that produces a metal salt, water, and carbon dioxide gas. The reaction can be represented by the following equation:12

$C a C O_{3} (s) + 2 H C l (a q) \to C a C l_{2} (a q) + C O_{2} (g) + H_{2} O (l)$

The characteristic bubbles, or effervescence, occur because the reaction initially forms carbonic acid ( $H_{2} C O_{3}$ ), which is unstable and spontaneously breaks down to release carbon dioxide gas. This gas-forming property has historically been used as a simple test to identify calcite and other carbonate-bearing minerals in the field.34