ICSE Class 10 Chemistry 2013 Solved Paper

O2 is evolved by heating KClO3 using MnO2 as a catalyst
2KClO3

MnO2

─────▸

2‌KCl+3O2

Question : 77

Total: 84

Calculate the mass of KClO3 required to produce 6.72 litre of O2 at STP. [atomic masses of K=39,Cl=35.5 , O=16]

Solution:

2KClO3

MnO2

─────▸

2‌KCl

3O2

‌2×(39+35.5+3×16)

‌

3×22.4

=2×122.5=245g

‌

=67⋅2l

67.2l of O2 produced by KClO3 at STP
=245g
6.72l of O2 produced by KClO3
‌=‌

245×6.72

67.2

‌=24.5g

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