• Share
Send to a Friend via Email

### Your suggestion is on its way!

An email with a link to:

was emailed to:

Thanks for sharing About.com with others!

Discuss in my forum

# Mole Relations in Balanced Equations

## Worked Problem: Mole Relations in Balanced Equations

Chemical equations state moles of reactants and products.

Comstock, Getty Images
These are worked chemistry problems showing how to calculate the number of moles of reactants or products in a balanced chemical equation.

Mole Relations Problem #1

Determine the number of moles of N2O4 needed to react completely with 3.62 mol of N2H4 for the reaction 2 N2H4(l) + N2O4(l) → 3 N2(g) + 4 H2O(l)

Solution

Find the relation between moles of N2H4 and N2O4 by using the coefficients of the balanced equation:

2 mol N2H4 is proportional to 1 mol N2O4

Therefore, the conversion factor is 1 mol N2O4/2 mol N2H4:

moles N2O4 = 3.62 mol N2H4 x 1 mol N2O4/2 mol N2H4

moles N2O4 = 1.81 mol N2O4

1.81 mol N2O4

Mole Relations Problem #2

Determine the number of moles of N2 produced for the reaction 2 N2H4(l) + N2O4(l) → 3 N2(g) + 4 H2O(l) when the reaction begins with 1.24 moles of N2H4.

Solution

Find the relation between moles of N2H4 and N2 by using the coefficients of the balanced equation:

2 mol N2H4 is proportional to 3 mol N2

In this case, we want to go from moles of N2H4 to moles of N2, so the conversion factor is 3 mol N2/2 mol N2H4:

moles N2 = 1.24 mol N2H4 x 3 mol N2/2 mol N2H4

moles N2 = 1.86 mol N2O4

1.86 mol N2

Anne Marie Helmenstine, Ph.D.