What is the mass of calcium oxide released during the decomposition of calcium carbonate with a mass of 400 g.

The reaction equation for the thermal decomposition of calcium carbonate:

CaCO3 (t) = CaO + CO2 ↑

Let’s find the amount of calcium carbonate substance:

v (CaCO3) = m (CaCO3) / M (CaCO3) = 400/100 = 4 (mol).

According to the reaction equation, from 1 mol of CaCO3, 1 mol of CaO is formed, therefore:

v (CaO) = v (CaCO3) = 4 (mol).

Thus, the mass of the formed calcium oxide:

m (CaO) = v (CaO) * M (CaO) = 4 * 56 = 224 (g).

Answer: 224 g.