Question Detail
Question
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? [C = 12; O = 16; Si = 28]
Correct Answer
Option A is the correct answer.
Detailed Explanation
Molar mass SiO₂ = 28+32=60 g/mol. Moles SiO₂ = 100/60 = 1.667 mol. Moles C = 100/12 = 8.333 mol. Stoichiometry: 1 mol SiO₂ requires 3 mol C. For 1.667 mol SiO₂, needed C = 5.00 mol. C is in excess. Excess C = 8.333 - 5.00 = 3.333 mol. Mass excess C = 3.333 × 12 = 40 g.
Hint
Determine limiting reactant and calculate excess.