Question

The gas which is responsible for the effervescence when vinegar reacts with baking soda is _______.

• A. oxygen
• B. carbon dioxide
• C. nitrogen dioxide
• D. hydrogen

Answer 1

The correct option is B carbon dioxide

The reaction of vinegar with baking soda occurs in two steps.

1st step: Vinegar reacts with sodium bicarbonate to form sodium acetate and carbonic acid. The reaction is given below:

${\text{NaHCO}}_3\text{(s)}+{\text{CH}}_3\text{COOH (aq)}\to {\text{CH}}_3\text{COONa (aq)}+{\text{H}}_2{\text{CO}}_3\text{(aq)}$

2nd step: Carbonic acid $\left({\text{H}}_2{\text{CO}}_3\right)$ is highly unstable and hence undergoes decomposition to release water along with carbon dioxide gas. The reaction is given below:

${\text{H}}_2{\text{CO}}_3\text{(aq)}\to {\text{H}}_2\text{O(l)}+{\text{CO}}_2\text{(g)}$

Hence, the effervescence is due to the formation of carbon dioxide gas.