Question

Study the figure given and name the gas which is responsible for the formation of effervescence.

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

Answer 1

The correct option is B

Carbon dioxide

When vinegar is added with baking soda, it results in a fizzy reaction. This happens because of the formation of carbon dioxide gas with strong effervescence which almost fills up the bottle. This reaction takes place in two steps:

Step 1: Acetic acid reacts with sodium bicarbonate to form sodium acetate and carbonic acid.
$NaHC{O}_3+C{H}_{3}COOH\to C{H}_{3}COONa+H_{2}C{O}_3$
Step 2: Carbonic acid is highly unstable and hence undergoes decomposition to release carbon dioxide.
$H_{2}C{O}_3\to H_{2}O+C{O}_2$