Question

3.2 moles of ammonia (NH3) is formed in the following reaction. How many grams of hydrogen reacted? 2 sig figs in your answer.
3H2 + N2 --> 2NH3

Answer 1

$3H_2 + N_2 \to 2NH_3$

As per stochiometry

$2$ moles of $NH_3$ require $3$ moles of $H_2.$

$3.2$ moles of $NH_3$ will produce $\frac{3}{2}\times 3.2=4.8$ moles of $H_2$ .

Molar mass of $H_2$ is $1\ g.$

Mass of $H_2$ required$=1\times 4.8=4.8\ g.$