#### Question

# How many moles form with this?

For the reaction shown, calculate how many moles of NH3 form when each of the following completely reacts.

3N2H4 (l) --> 4NH3 (g) + N2 (g)

5.6 mol N2H4

I'm so confused? Does anyone know how to do this?

#### Answer

The ratio of N2H4 to NH3 is 3 to 4.

This ratio works perfectly for moles.

So ... 3 is to 4 as 5.6 is to ____

3/4 = 5.6/ x

x = 7.5 mol NH3

Use the mole ratio to solve.

Your given the balanced chemical equation.

Your given 5.6 mol of N2H4, and you are trying to find out how many moles of NH3 will form.

So, start with what you know.

5.6 mol of N2H4...set up your mole ratio so that the moles of N2H4 will cancel (the units will cancel).

The top part of the ratio will be 4 mol NH3

Bottom part of the ratio will be 3 mol N2H4 (both these values come from the balanced chem. eq).

Then do the math:

5.6 mole of N2H4 divided by 3 mol of N2H4 (moles of N2H4 cancel), and then multiply that number by 4 (number of moles of NH3). The moles of NH3 is what you are trying to solve for, and they are the only units left. Then you have your answer.

Good luck!