Question

${\mathrm{O}}_2$ is evolved by heating ${\mathrm{KClO}}_3$ using ${\mathrm{MnO}}_2$ as a catalyst
$2{\mathrm{KClO}}_3\to 2\mathrm{KCl}+3{\mathrm{O}}_2$

Calculate the number of moles of oxygen present in the above volume and also the number of molecules.

Answer 1

• $22.4\mathrm{L}\text{of oxygen}⟶1\text{mole}$
• $6.72\mathrm{L}\text{of oxygen}⟶\frac{1}{22.4}\times 6.72=0.3moles$
• $1\text{mole}⟶6\times {10}^{23}\text{molecules}$
• $0.3\text{mole}⟶0.3\times 6\times {10}^{23}=1.8\times {10}^{23}\text{molecules}$
• Therefore, the number of moles of oxygen present in the above volume and also the number of molecules is $1.8\times {10}^{23}$ molecules.