A sample with a mass of 15.6 g, consisting of oxide and calcium carbonate, was calcined

| September 1, 2021 | education

A sample with a mass of 15.6 g, consisting of oxide and calcium carbonate, was calcined, as a result of which a gas with a volume of 2.24 liters was released. Determine the mass fraction in% of calcium oxide in the sample.

When calcined, calcium oxide does not change, and calcium carbonate decomposes into calcium oxide and carbon dioxide:

CaCO3 = CaO + CO2.

The volume of 1 mol of gas under normal conditions is 22.4 liters, which means that 2.24 / 22.4 = 0.1 mol of CO2 was released as a result of the reaction.

This means that there was 0.1 mol of CaCO3 in the sample.

Molar mass М (CaCO3) = 40 + 12 + 16 × 3 = 100 g / mol, so the mass of CaCO3 is 10 g.

Calcium oxide mass: 15.6 – 10 = 5.6 g, which corresponds to a mass fraction of 5.6 / 15.6 × 100% = 35.9%.



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