ICSE Class 10 Chemistry 2013 Solved Paper

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

2 {\KClO}_3 \ {─────▸}↖{ {\MnO}_2} 2 {\KCl}+3 {\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 {\g}

{\KClO}_3

contains

=3 \;\text " moles of oxygen "\;

∴ 24.5 {\g}

{\KClO}_3

contains

\;=\;{3 × 24.5}/{245}

\;=0.3 \;\text " mole. "\;

Ans.
Since, 1 mole of oxygen contain

=6.022 × 10^{23} \;\text " molecules "\;

Therefore,

0 ⋅ 3

mole of oxygen contain

\;=6.022 × 10^{23} × 0.3

\;=1.8066 × 10^{23} \;\text " molecules "\;

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