Question

How many moles of nitrogen are required to produce 8.2 mol of ammonia on a reaction with an excess of hydrogen?

Answer 1

The balanced chemical equation is:
$N_2+3H_2\to 2N{H}_3$
From stoichiometry,
2 mol of $N{H}_3$ is produced from 1 mol of $N_2$.
8.2 mol of $N{H}_3$ will be produced from = $\frac{1}{2}\times 8.2$ = 4.1 mol of $N_2$