Question

For the reaction represented by the equation `N_2 + 3H_2 -> 2NH_3`, how many moles of nitrogen are required to produce 18 mol of ammonia?

Answer 1

`9molN_2`

Explanation:

The reaction is:

`N_2(g) + 3H_2(g)->2HN_3(g)`

The molar ratio between Nitrogen and ammonia is `1:3`, therefore, to produce 18 moles of ammonia, we will need:

`?molN_2=18cancel(molNH_3)xx(1molN_2)/(2cancel(molNH_3))=9molN_2`

Answer 2

Compare the mole ratio between `NH_3` and `N_2`.
The mole ratio between `NH_3 : N_2` is `2:1`.

If 2 moles of `NH_3` gives you 1 mole of `N_2`,

then 18 moles of `NH_3` should give you:
[18 moles`-:` 2 `xx` 1] = 9 moles of `N_2`

Therefore 9 moles of nitrogen are required to produce 18 moles of ammonia.