Question

Sam accidently dropped a bottle of concentrated hydrochloric acid on tiles made up of calcium carbonate. He noticed bubbles being formed on the floor. Which gas is responsible for this bubble formation?

• A. Oxygen
• B. Hydrogen
• C. Nitrogen
• D. Carbon dioxide

Answer 1

The correct option is D Carbon dioxide

When hydrochloric acid is dropped on the tiles (calcium carbonate) a chemical reaction takes place. The reaction between calcium carbonate $\left({\text{CaCO}}_3\right)$ and hydrochloric acid $\left(\text{HCl}\right)$ is as follows:

${\text{CaCO}}_3\text{(s)}+\text{2HCl}\text{(aq)}\to {\text{CaCl}}_2\text{(aq)}+{\text{CO}}_2\text{(g)}+{\text{H}}_2\text{O}\text{(l)}$

Carbon dioxide $\left({\text{CO}}_2\right)$ gas is evolved in the reaction. This is responsible for the formation of bubbles on the tiles when the acid is spilt.