A 40 g mixture of CaCO₃, MgCO₃, and SiO₂ (inert) was heated. The mass of the mixture decreased by 13.2 g. If the molar ratio of CaCO₃ to MgCO₃ was 2:1, find the mass of the inert SiO₂ in the mixture.
- 5 g
- 14.8 g
- 10.2 g
- 25.2 g
📝 Detailed explanation
Loss of mass is due to CO₂: 13.2 g.Total moles of CO₂ = 13.2 / 44 = 0.3 mol.
Let moles of CaCO₃ = 2x and MgCO₃ = x.
2x + x = 0.3, so 3x = 0.3, x = 0.1 mol.
Mass of CaCO₃ = 0.2 × 100 = 20 g.
Mass of MgCO₃ = 0.1 × 84 = 8.4 g.
Mass of SiO₂ = 40 - (20 + 8.4) = 11.6 g.
Wait, re-checking calculation: 40 - 28.4 = 11.6 g.
If the ratio was different, the result would change. Based on 2:1 ratio, it is 11.6 g.