Question

$245 \mathrm{~g}$ impure sample of $\mathrm{KClO}_3(\mathrm{~s})$ on heating gives $12 \mathrm{~g} \mathrm{O}_2(\mathrm{~g})$ according to $2 \mathrm{KClO}_3(\mathrm{~s}) \rightarrow 2 \mathrm{KCl}(\mathrm{s})+3 \mathrm{O}_2(\mathrm{~g})$ Calculate \% purity of sample?

Answer 1

$2 \, \text{KClO}_{\text{3}} \rightarrow 2 \, \text{KCl} + 3 \, \text{O}_{\text{2}}$

Let the % purity = $\text{x}$

Mole of $KClO_{3}$ = $\frac{245}{122.5}\times \frac{x}{100}$ = $\frac{2 x}{100}$

Mole of $O_{2}$ = $\frac{2 x}{100}\times \frac{3}{2}$

$\frac{2 x}{100}\times \frac{3}{2}\times 32=12$

(% purity of sample) $\text{x} \, \text{=} \, \text{12} \text{.5}$