If 10.11 g of limestone decomposes by heat to give 8.51 g of solid calcium oxide and carbon dioxide gas, what is the mass of carbon dioxide produced?

Answer 1

I ASSUME the 8.51g is the mass of the CaO and NOT the combined mass of CaO + CO2. The way the problem is stated makes one think the sum of the two is 8.51g.

CaCO3 ==> CaO + CO2
Mass CO2 = loss in weight = 10.11-8.51 = 1.6g.
mols CO2 = grams/molar mass = ?
From the equation you can see that mols CO2 = mols CaCO3.
Convert mols CO2 to mols CaCO3 then to g CaCO3

Then (g CaCO3/10.11)*100 = ?% CaCO3