When a bicarbonate or carbonate compound is mixed with an acid, why are bubbles formed?

• A. Because the acid decomposes into hydrogen gas (H_2).
• B. Because carbon dioxide gas (CO_2) is produced during the reaction.
• C. Because water vapor is formed and escapes as bubbles.
• D. Because oxygen gas (O_2) is released from the acid.

Answer: (B)

Verified step by step guidance

1. Identify the reactants involved: a bicarbonate or carbonate compound and an acid.
2. Recall that bicarbonates (HCO\_3\^-) and carbonates (CO\_3\^{2-}) react with acids to produce carbonic acid (H\_2CO\_3).
3. Understand that carbonic acid (H\_2CO\_3) is unstable and quickly decomposes into water (H\_2O) and carbon dioxide gas (CO\_2).
4. Recognize that the carbon dioxide gas (CO\_2) formed escapes as bubbles, which is why bubbling is observed during the reaction.
5. Conclude that the bubbles are not due to hydrogen gas, water vapor, or oxygen gas, but specifically due to the release of carbon dioxide gas.