Question

How many moles of hydrogen are needed to completely react with two moles of nitrogen? According to the reaction: N2 + 3H2 -->2NH3

Answer 1

`"6 moles"`

Explanation:

Take a look at the balanced chemical equation for this synthesis reaction

`"N"_text(2(g]) + color(red)(3)"H"_text(2(g]) -> 2"NH"_text(3(g])`

Notice that you have a `1:color(red)(3)` mole ratio between nitrogen gas and hydrogen gas. This means that, regardless of how many moles of nitrogen gas you have, the reaction will always consume twice as many moles of hydrogen gas.

So, if you have `2` moles of nitrogen taking part in the reaction, you will need

`2color(red)(cancel(color(black)("moles N"_2))) * (color(red)(3)" moles H"_2)/(1color(red)(cancel(color(black)("mole N"_2)))) = "6 moles H"_2`