What mass of CaO can be obtained by firing 1000 g of CaCO3 limestone containing 8 percent of impurities?

Reaction equation: CaCO3 = CaO + CO2
If limestone contains 8% impurities, then 92% is pure calcium carbonate. Let’s find the mass of the calcium carbonate substance m = 0.92 * 1000 g = 920 g. Now we will find the amount of the calcium carbonate substance n = m / M = 920 g / 100 g / mol = 9.2 mol. According to the reaction from 1 mol of carbonate, 1 mol of calcium oxide is obtained, which means n (CaCo3) = n (CaO) = 9.2 mol. The mass of the oxide is m = n * M = 9.2 mol * 56 g / mol = 515.2 g (M is the molar mass, determined according to the periodic table).
Answer: 515.2 g.