Question
Decomposition of NaHCO3 takes place at 270°C. In a sample containing Na2CO3 and NaHCO3, the heating at 270°C results in the loss of 10% by weight. What is the percentage composition of the sample?
Solution
The balanced chemical equation is
2NaCHO3
Na2CO3 + H2O 
+ CO2 
2x(23+1+12+48) 2+16 12 + 2 x16
= 168 g = 18 g = 44 g
Stoichiometry indicates that loss of 62 g of mass takes place from 168 g of NaHCO3. So loss of 10 g of mass takes place from
Thus the percentage of
in the sample = 27.1%
and percentage of Na2CO3 in the sample
= 100 - 27.1 = 72.9%
2NaCHO3
Na2CO3 + H2O + CO2 2x(23+1+12+48) 2+16 12 + 2 x16
= 168 g = 18 g = 44 g
Stoichiometry indicates that loss of 62 g of mass takes place from 168 g of NaHCO3. So loss of 10 g of mass takes place from
Thus the percentage of
in the sample = 27.1%and percentage of Na2CO3 in the sample
= 100 - 27.1 = 72.9%
