Calcium combines with boron, as represented by the chemical equation below:
Ca + 6B → CaB6
What is the minimum amount of calcium, in grams, that could completely react with 54.0 g of boron?

Question

Quizplus · Accepted Answer

First, calculate the molar mass of boron (B), which is approximately 10.81 g/mol. For boron, 54.0 g corresponds to $54.0 \, \text{g} \div 10.81 \, \text{g/mol} = 5 \, \text{mol}$ of boron. The chemical equation shows that 6 moles of boron (B) react with 1 mole of calcium (Ca). Therefore, for 5 moles of boron, we need $5 \div 6 = 0.833$ moles of calcium. The molar mass of calcium is approximately 40.08 g/mol, so the mass of calcium needed is $0.833 \, \text{mol} \times 40.08 \, \text{g/mol} = 33.4 \, \text{g}$.

Calcium Combines with Boron, as Represented by the Chemical Equation