Question

When ethanoic acid is added to a solution of substance X, colourless and odourless gas Y is liberated. The gas Y turns lime water milky. The substance X is : (A) Sodium hydrogen carbonate (B) Sodium hydroxide (C) Sodium acetate (D) Sodium chloride.

Answer 1

(A) Sodium hydrogen carbonate.
When ethanoic acid reacts with sodium hydrogen carbonate or sodium carbonate, colourless and odourless gas carbon dioxide is released which turns lime water milky.

Answer 2

When ‘ethanoic acid’ is added to a “solution of substance” sodium hydrogen carbonate, a colourless and odorless gas carbon dioxide is liberated which turns lime water milky.

Explanation:

• Ethanoic acid or acetic acid reacts with “sodium hydrogen carbonate” or baking soda in a double displacement reaction and forms sodium ethanoate and carbonic acid which later decomposes to water releasing carbon dioxide.

        $\mathrm{NaHCO}_{3}+\mathrm{CH}_{3} \mathrm{COOH} \rightarrow \mathrm{CH}_{3} \mathrm{COONa}+\mathrm{CO}_{2} \uparrow+\mathrm{H}_{2} \mathrm{O}$

• Due to the release of \mathrm{CO}_{2}, a fizzing reaction with brisk effervescence takes place during the reaction.