To calculate the percent yield, we can use the following formula:

% yield = (actual yield / theoretical yield) x 100

In this case, the actual yield is 1.24 mol and the theoretical yield is 1.70 mol, so:

% yield = (1.24 mol / 1.70 mol) x 100

% yield = 72.9%

Therefore, the percent yield of aluminum oxide is 72.9%.