A 40 g mixture of CaCO₃ and MgCO₃ is heated to constant mass. As a result, 19.36 g of CO₂ gas is released. Calculate the mass of CaCO₃ in the initial mixture.
- 19 g
- 21 g
- 10 g
- 30 g
📝 Detailed explanation
n(CO₂) = 19.36 / 44 = 0.44 mol.Let x = mass CaCO₃, y = mass MgCO₃.
x + y = 40.
x/100 + (40-x)/84 = 0.44.
84x + 100(40-x) = 0.44 * 8400 = 3696.
84x + 4000 - 100x = 3696.
-16x = -304.
x = 19 g.