Question

The amount of calcium oxide produced on heating 150 kg limestone (75% pure) is _______ kg. (Nearest integer)
Given: Molar mass (in g mol$^{-1}$) of Ca-40, O-16, C-12

Hint:

When calculating mass from moles, always use the correct molar masses and conversion factors (grams to kilograms) to ensure accurate results.

Answer 1

Correct Answer: 63

Given that: \[ \text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2 \] We start by calculating the mass of CaCO$_3$: \[ \text{mass of CaCO}_3 = \frac{150 \times 75}{100} = 112.5 \, \text{kg} \] Next, calculate the moles of CaCO$_3$: \[ n_{\text{CaCO}_3} = \frac{\text{mass}}{\text{molar mass of CaCO}_3} = \frac{1125000}{100} = 1125 \, \text{moles} \] Since each mole of CaCO$_3$ produces 1 mole of CaO, the moles of CaO formed will be the same: \[ n_{\text{CaO}} = 1125 \, \text{moles} \] Now, we calculate the mass of CaO: \[ \text{mass of CaO} = n_{\text{CaO}} \times \text{molar mass of CaO} = 1125 \times 56 = 63000 \, \text{grams} = 63 \, \text{kg} \] 
Thus, the amount of calcium oxide produced is 63 kg.