Answer:
Percent yield = 85.4%
Explanation:
Given data:
Mass of Al = 2.5 g
Mass of oxygen = 2.5 g
Mass of aluminium oxide = 3.5 g
Percent yield = ?
Solution:
Chemical equation:
4Al + 3O₂ → 2Al₂O₃
First of all we will calculate the number of moles of each reactant.
Number of moles of Al:
Number of moles = mass/ molar mass
Number of moles = 2.5 g/ 27 g/mol
Number of moles = 0.09 mol
Number of moles of oxygen:
Number of moles = mass/ molar mass
Number of moles = 2.5 g/ 32 g/mol
Number of moles = 0.08 mol
Now we will compare the moles of aluminium oxide with oxygen and aluminium.
Al : Al₂O₃
4 : 2
0.09 : 2/4×0.09 = 0.045
O₂ : Al₂O₃
3 : 2
0.08 : 2/4×0.08 = 0.04
The number of moles of aluminium oxide produced by oxygen are less so it will limiting reactant.
Theoretical yield of aluminium oxide:
Mass = number of moles × molar mass
Mass = 0.04 mol × 101.96 g/mol
Mass = 4.1 g
Percent yield:
Percent yield = actual yield /theoretical yield × 100
Percent yield = 3.5 g/ 4.1 g × 100
Percent yield = 85.4%
