Calculating Percent Yield Question

Question

Aluminum oxide is produced in a single replacement reaction between aluminum and chromium (II) oxide. Calculate the percent yield if 603.0g of chromium(II) oxide were used with 422.5g of aluminum and 208.0g of aluminum oxide were actually produced. Identify the limiting reagent and calculate your percent yield.

Answer 1

2Al + 3CrO ==> Al₂O₃ + 3Cr ... balanced equation

moles CrO used = 603.0 g x 1 mol/67.99 g = 8.869 moles

moles Al = 422.5 g x 1 mol/26.98 g = 15.66 moles

Based on mole ratio in balanced equation, CrO is LIMITING

Theoretical yield of Al₂O₃ = 8.869 mol CrO x 1 mol Al₂O₃/3 mol CrO x 101.96 g/mole = 295.5 g

percent yield = 208.8 g/295.5 g (x100%) = 70.66%