Question Detail
Question
Silicon carbide, an abrasive, is made by the reaction of silicon dioxide with graphite: SiO₂ + 3C → SiC + 2CO. If 100 g of SiO₂ and 100 g of C are reacted as far as possible, which one of the following statements will be correct?
Correct Answer
Option D is the correct answer.
Detailed Explanation
Moles SiO₂ = 100/60 = 1.667 mol. Moles C = 100/12 = 8.333 mol. Reaction requires 3 mol C per 1 mol SiO₂. C needed for all SiO₂ = 1.667×3 = 5.00 mol. C available = 8.333 mol, so C is in excess. Excess C = 8.333 - 5.00 = 3.333 mol. Mass excess C = 3.333 × 12 = 40 g.
Hint
Determine the limiting reactant first.