Question

When sample of baking soda is strongly ignited in crucible it suffered loss in weight of $3.1g$ the mass of baking soda is-

• A. $16.8g$
• B. $8.4g$
• C. $11.6g$
• D. $4.2g$

Answer 1

Answer: (B)

$8.4g$

The reaction is:

$2NaHC{O}_3\to N{a}_{2}C{O}_3+H_{2}O+C{O}_2$

The loss in weight is due to water and carbon dioxide.

$2$ moles $(2\times 84g)$ of sodium bicarbonate gives $1$ mole $\left(18g\right)$ of water and $1$ mole of carbon dioxide $\left(44g\right)$.

Thus, decomposition of $168g$ of sodium bicarbonate will result in loss in weight of $18+44=62g$

The loss in weight of $3.1$ g corresponds to $\frac{168}{62}\times 3.1=8.4g$ of sodium bicarbonate.

Option B is correct.