Question

50g of caco3 decomposes on heating to give cao and 20g off co2? The approximate purity of caco3 is

Answer 1

Given info : 50g of CaCO3 decomposes on heating to give cao and 20g off CO2 gas.

To find : the approximate purity of CaCO3 is....

Solution : decomposition of CaCO3 is ..

CaCO₃ ⇒ CaO + CO₂

here we see 1 mole of CaCO3 decomposes into 1 mole of CaO and 1 mole of CO2.

100g of CaCO3 decomposes into 56g of CaO and 44g of CO2.

[ molecular wt of CaCO3 = 100g

molecular wt of CaO = 56g

molecular wt of CO2 = 44g ]

So, 20g of CO2 is produced by 100/44 × 20 g = 45.45 g

Therefore the impurity in 50g of CaCO3 sample = 50 - 45.45 = 4.55g

therefore percentage purity of CaCO3 = 45.45/50 × 100 = 90.9 ≈ 91 %