1. Unit 5: The Mole and Stoichiometry
Mole as a Bridge

2. Moles and Gases At standard temperature and pressure (STP) . . .
1 mole of any gas will occupy the same volume as any other gas at the same temperature and pressure.
At STP (which is 0oC and 1 atm):
1 mole of any gas occupies a volume of 22.4 liters.
Therefore, 1 mole = 22.4 liters
(of any gas at STP)

3. Examples: 0.0035 moles 22.4 Liters 1 mole = 0.078 Liters CH4
What is the volume of moles of CH4 at STP?
moles
22.4 Liters
1 mole
= Liters CH4

4. What is the number of moles of oxygen in an 85 Liter sample at STP?
What is the mass of 18 liters of carbon dioxide gas at STP?
85 Liters
1 mole
= 3.8 moles
22.4 L
1 mole
18 Liters
44.01 g CO2
22.4 L
1 mole
= 35 grams

5. One Mole can equal 3 different things
X 1023 atoms or molecules
2. The mass of any element or molecule in grams
Liters of any gas at Standard Temperature and Pressure (STP)
Since the mole can equal any one of these, it can also serve as a bridge to convert from one to another of them.

6. Mole as a Bridge “÷” “x” “÷” “x” “x” “÷” Mass (Molar Mass) Particles
Volume
(22.4L)
Going out of the Mole, MULTIPLY (top of T-chart)
Going into the Mole, DIVIDE (bottom of T-chart)

7. Using the Mole as a Bridge Examples:
How many grams are there in 7.4 x 1023 molecules of AgNO3?
7.4 x 1023 molecules g
1 mole AgNO3
6.02 x 1023 molecules
1 mole AgNO3
= 209 grams = 210 grams (sig figs!)

8. Using the Mole as a Bridge Examples
How many molecules are there in 230 grams of CoCl2?
6.02 x 1023 molecules
230 g CoCl2
1 mole
g CoCl2
1 mole
= 1.07 x 1024 molecules

9. Using the Mole as a Bridge Examples
What is the volume of 150 grams of N2O gas at STP?
150 g N2O
1 mole
22.4 L
44.02 grams
1 mole
= 76.3 Liters