Question

Sum of molar mass of gas $(x) & (y)$ is :

• A. 44
• B. 88
• C. 46
• D. 160

Hint:

Carboxylic acids react with sodium bicarbonate to yield $\text{CO}_2$ gas and with active metals to yield $\text{H}_2$ gas. Always remember the molar masses of these common gases.

Answer 1

The Correct Option is C

Reaction 1: $\text{RCOOH} + \text{NaHCO}_3 \rightarrow \text{RCOONa} + \text{H}_2\text{O} + y(g)$.
Gas $(y)$ is Carbon Dioxide ($\text{CO}_2$). $M_y = 44 \text{ g/mol}$.
Reaction 2: $2\text{RCOOH} + 2\text{Na} \rightarrow 2\text{RCOONa} + x(g)$.
Gas $(x)$ is Hydrogen ($\text{H}_2$). $M_x = 2 \text{ g/mol}$.
Sum of molar masses $= M_x + M_y = 2 + 44 = 46$.