Question

When a sample of baking soda is strongly ignited in a crucible, it suffered a loss is the weight of $3.1$g. The mass of baking soda is:

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

Answer 1

The correct option is B $8.4$g

Given, $NaHC{O}_3$ is strongly ignited & it suffered a loss of $3.1g$ in weight

The reaction involved is

$2NaHC{O}_3⟶N{a}_{2}C{O}_3+C{O}_2\uparrow +H_{2}O⟶1$

Here the loss in weight of $NaHC{O}_3$ occurs due to $C{O}_2+H_{2}O⟶Mainpoint$

We know,

Molar mass of $NaHC{O}_3=2\times 84=168gms$ $[\because 1]$

Also mass of $H_{2}O+C{O}_2=18g+44g=62gms$ $[\because 1]$

Thus, $168gms$ of $NaHC{O}_3$ occurs a loss of $62gms$ on decomposition

So, $3.1gms$ loss was given by

$3.1gm\times \frac{168g}{62g}NaHC{O}_3$

$\Rightarrow 8.4g$ of $NaHC{O}_3$