Calculate the number of moles of oxygen ...

ICSE Class 10 Chemistry 2013 Paper

$\mathrm{O}_2$ is evolved by heating $\mathrm{KClO}_3$ using $\mathrm{MnO}_2$ as a catalyst

2 \mathrm{KClO}_3 \xrightarrow[\mathrm{MnO}_2]{} 2 \mathrm{KCl} + 3 \mathrm{O}_2

Question : 78 of 84

Marks: +1, -0

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

Solution:

245 \mathrm{g}

\mathrm{KClO}_3

contains

=3 \text{ moles of oxygen }

\therefore 24.5 \mathrm{g}

\mathrm{KClO}_3

contains

\;=\;\frac{3 \times 24.5}{245}

\;=0.3 \text{ mole. }

Ans.

Since, 1 mole of oxygen contain

=6.022 \times 10^{23} \text{ molecules }

Therefore,

0 \cdot 3

mole of oxygen contain

\;=6.022 \times 10^{23} \times 0.3

\;=1.8066 \times 10^{23} \text{ molecules }

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