Question

Ammonia, NH3, can be made by reacting nitrogen and hydrogen and the equation is N2 + 3H2 --> 2NH3 How many moles of NH3 can be made if 19 moles of H2 react with enough N2? mol

Answer 1

Make a proportion
3 H2 - 2 NH3
19H2 - x
x = (19x2)/3= 12,666666

Answer 2

You have a balanced equation that says one mole of $N_2$ plus three moles of $H_2$ react to produce two moles of $NH_3$. So if 2 moles of hydrogen are required for 3 moles of ammonia, then you can make the simplest of equations to solve this. That is,

$3n_H=2n_A$

Solving for the number of moles of hydrogen then

$n_H=\frac{2}{3}n_A$

You were given the number of moles of ammonia so plug it in and you are done!