Question

A $10mg$ effervescent tablet containing sodium bicarbonate and oxalic acid releases $0.25ml$ of $C{O}_2$ at $T=298.15K$ and $p=1$ bar. If molar volume of $C{O}_2$ is $25.0L$ under such condition, what is the percentage of sodium bicarbonate in each tablet?
$[\text{Molar mass of}NaHC{O}_3=84gmo{l}^{-1}]$

• A. $16.8$
• B. $0.84$
• C. $33.6$
• D. $8.4$

Answer 1

The correct option is D $8.4$

Moles of $C{O}_2$ evolved $=\frac{0.25}{25\times {10}^3}={10}^{-5}$
$\therefore \text{moles of}NaHC{O}_3={10}^{-5}$
$\therefore \text{mass of}NaHC{O}_3=84\times {10}^{-5}g$
$=0.84\times {10}^{-3}g$
$=0.84mg$
$\therefore \%$ by wight $=\frac{0.84}{10}\times 100$
$=8.4\%$