Q.
A 1.50g sample of KHCO3 having 80% purity is strongly heated. Assuming the impurity to ste thermally stable, the loss in weight of the sample, on heating is:
2320
214
Some Basic Concepts of Chemistry
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Solution:
2KHCO3ΔK2CO3+H2O+CO2↑
Loss of wt. will be because of CO2 escaped
Total KHCO3 chosen =1.50g
percentage purity =80%
∴ Pure KHCO3=1.50×10080=1.2g
M. mass of KHCO3=39+1+12+3×16=100g
moles of pure KHCO3=1001.2=0.012 moles
From balanced equation-
2 moles of KHCO3 yield moles of CO2=1
0.012 moles of KHCO3 yield moles of CO2=21×0.012