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 : 77 of 84

Marks: +1, -0

Calculate the mass of

{\KClO}_3

required to produce 6.72 litre of

{\O}_2

at STP. [atomic masses of

{\K}=39, {\Cl}=35.5

O=16]

Solution:

\table 2 {\KClO}_3 ,\ {─────▸}↖{ {\MnO}_2} ,2 {\KCl},+,3 {\O}_2 ; \;2 ×(39+35.5+3 × 16) ,,,, 3 × 22.4; =2 × 122.5=245 {\g},,,, =67 ⋅ 2 l

67.2 l

{\O}_2

produced by

{\KClO}_3

at STP

=245 {\g}

6.72 l

{\O}_2

produced by

{\KClO}_3

\;=\;{245 × 6.72}/{67.2}

\;=24.5 {\g}

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