Question

Given the chemical equation `"N"_2("g") + "3H"_2("g")"``rarr``"2NH"_3("g")"`, how many moles of `"NH"_3"` can be produced if `"10. mol H"_2"` reacts completely with nitrogen?

Answer 1

You will get 6.7 mol of NH₃.

The chemical equation is N₂ + 3H₂ → 2NH₃.

This tells you that 3 mol of H₂ give 2 mol of NH₃. So,

`"10. mol H"_2 × ("2 mol NH"_3)/("3 mol H"_2) = "6.7 mol H"_2`

Answer 2

`"10. mol H"_2"` will produce `"6.7 mol NH"_3"` when it reacts completely with nitrogen.

Start with the balanced equation, which you have.

`"N"_2("g")` + `"3H"_2("g")"` `rarr` `"2NH"_3("g")"`

From the balanced equation, we can see that the mole ratio of `"H"_2"` to `"NH"_3"` is 3:2. We can write this mole ratio as two conversion factors, one of which will be used to solve the problem.

Two Mole Ratio Conversion Factors

`"3 mol H2"/"2 mol NH3"` and `"2 mol NH3"/"3 mol H2"`

We want to know how many moles of ammonia can be produced from 10. moles of hydrogen. We need to multiply 10. moles `"H"_2` times the mole ratio conversion factor that cancels moles `"H"_2"` and leaves moles `"NH"_3`.

`"10. mol H"_2` x `"2 mol NH3"/"3 mol H2"` = `"6.7 mol NH"_3"`