Consider this reaction : 2Al2O3 → 4Al + 3O2
The number of moles of Al2O3 can be determined from its mass →
Number of moles of AL2O3 = mass/molar mass
=51/(27x2+16x3)
= 0.5 mol
Now, calculate aluminium's number of moles from the mole ratio →
Mole ratio 4(Al) : 2(Al2O3)
Number of moles of Al = (4/2) x0.5mol = 1 mol
Mass of Al = number of moles x molar mass
= 1x27
= 27kg (theoretical yield)
Given, actual yield = 17kg
Therefore, percentage yield = (actual yield / theoretical yield ) x 100
= (17/27)x100
= 62.96%