Question

How would you determine the number of moles of `N_2` that are required to produce 12 mol of `NH_3` using the equation: `N_2+ 3H_2 -> 2NH_3`?

Answer 1

Use the mole ratio of `(NH3)/ N_2`the ratio is 2:1 or 1:2 so it will take 6 moles of `N_2` to make 12 moles of `NH_3`

Explanation:

There is no coefficient in front of the `N_2` in the reactants. This means that there is one mole of `N_2` required in the balanced equation.

There is a 2 coefficient in front of the `NH_3` in the products.

This is a 1:2 or 2:1 ratio. Since the desired outcome is `NH_3` put the 2 on top and the 1 on the bottom

`6 (N_2) xx 2/1 = NH_3`

`6 xx 2 = 12 (NH_3)`

Answer 2

You need 6 moles of `N_2` to produce 12 moles of `NH_3`.

Explanation:

The coefficients in a chemical reaction give the molar ratios of reactants and products in that reaction. You can read the above reaction (The Haber process) as saying "For every 1 mol of `N_2`, 3 moles of `H_2` will react and 2 moles of `NH_3` will be produced." So, if our ratio of `N_2` to `NH_3` is 1:2, and we need to produce 12 moles of `NH_3`, then we will need half as many moles of `N_2`, or 6 moles.