When 29.8 mole of aluminum reacts with excess oxygen according to the following reaction, how many moles of aluminum oxide can be produced?

4 Al + 3 O2 → 2 Al2O3

Use dimensional analysis.

first, you put 29.8 mole of Al at the top.

And, in the next column you put 2 mole of Al2O3 at the top and 4 mole of Al at the bottom.

Then, you multiply 29.8 and 2 and then divide by 4. that will give you the answer 14.9 mole of Al2O3.