Question

What mass of potassium chlorate $\left(KCl{O}_3\right)$ on heating gives 1.491 g of potassium chloride (KCl) and 0.672 litres of oxygen at NTP?

• A. 2.451 g
• B. 2.0 g
• C. 1.2256 g
• D. 4.902 g

Answer 1

The correct option is A 2.451 g

Decomposition of $KCl{O}_3$ is given by,

$2KCl{O}_3\stackrel{△}{\to }2KCl+3O_{2}2mole2moles3moles1.491g0.672$

$1$ mole of $O_2$ occupies $22.4d{m}^3$ of $O_2$
Then $0.672d{m}^3$ of $O_2=\frac{0.672}{22.4}=0.03$ moles.

$1$ mole of $O_2=32g.$

$\therefore 0.03$ moles of $O_2=32\times 0.03=0.96g$

$\therefore$ Mass of potassium chlorate $=M\left(KCl\right)+M\left(O_2\right)=1.491+0.96=2.451g$