How many grams of calcium oxide is formed during the decomposition of 200 g of limestone with 10% impurities?

The decomposition reaction of calcium carbonate is described by the following chemical reaction equation:
CaCO3 = CaO + CO2;
One mole of calcium carbonate forms one mole of calcium oxide and carbon monoxide.
Determine the mass of pure calcium carbonate.
m CaCO3 = 200 x 90% = 180 grams;
Determine the amount of substance in 180 grams of calcium carbonate.
Its molar mass is:
M CaCO3 = 40 + 12 + 16 x 3 = 100 grams / mol;
The amount of substance will be:
N CaCO3 = 180/100 = 1.8 mol;
The same amount of calcium oxide will be obtained.
The molar mass of calcium oxide is:
M CaO = 40 + 16 = 56 grams / mol;
The mass of calcium oxide will be:
m CaO = 56 x 1.8 = 100.8 grams;