1. Molar Ratios By Elise Rippelmeyer Elise Rippelmeyer
4th Period Standard Chemistry with DA Young
3/2/07
Molar Ratios PowerPoint Presentation

2. Molar Ratios are… A molar ratio is a ratio between
the number of moles of any two
species involved in a chemical reaction.

3. For Example: 2H2 + O2  2H2O Six Molar ratios can be written:
2 mol mol 2 mol
Six Molar ratios can be written:
2 mol H2 2 mol H2 1 mol O2
1 mol O2 2 mol H2O 2 mol H2
1 mol O mol H2O 2 mol H2O
2 mol H2O 2 mol H2 1 mol O2

4. Why?
We use the mole ratio to convert the number of moles of one substance to the corresponding number of moles of another substance in a chemical reaction.

5. For Example:
To calculate the number of moles of H2O that can be obtained from 4.0 mol of O2, we use the mol ratio 2 mol H2O/1 mol O2.
2 mol H2O
(4.0 mol O2) = 8.0 mol H2O
1 mol O2

6. 3 Basic Steps 1. Convert the quantity of starting substance to moles
2. Convert the moles of starting substance to moles of desired substance
3. Convert the moles of desired substance to the units specified in the problem

7. The End!