Question

the mass of CaO obtained by heating 100g(90%)of lime stone(CaCO3)is

Answer 1

CaCO3----> CaO +CO2
molecular weight:
CaCO3 = 100g
CaO = 56g
100 g of CaCO3 give 56g of CaO
pure CaCO3 = 90/100*100 = 90g
So, 90g of CaCO3 will give = 56/100*90 = 50.4g of CaO

Answer 2

Answer: 50.4 grams

Explanation:

Heating of limestone is shown by:

$CaCO_3\rightarrow CaO+CO_2$

From the balanced chemical equation:

100 g of $CaCO_3$ decomposes to give 56 g of $CaO$  

Thus when purity is 100% , the mass of $CaO$ obtained by heating 100g of lime stone is = 56 g

When purity is 90%, the mass of $CaCO_3$ is =$\frac{90}{100}\times 100=90g$

If 100g of $CaCO_3$ gives = 56 g of $CaO$

90 g of $CaCO_3$ gives =$\frac{56}{100}\times 90=50.4 g$ of $CaO$

The mass of $CaO$ obtained by heating 100g (90%) of lime stone $CaCO_3$ is 50.4 grams.