1. Topic 10 Gases
III. Ideal Gas Law

2. Reminder: Avogadro’s Principle
Equal volumes of gases contain equal numbers of moles
at constant temp & pressure
true for any gas V n
Reminder: Molar Volume: The volume that 1 mole of gas occupies at STP. That volume is 22.4 L.

3. Example: A container hold 3
Example: A container hold 3.45 L of carbon dioxide at 1 atmosphere of pressure at 0 degrees Celsius. How many moles of carbon dioxide are in the container?

4. UNIVERSAL GAS CONSTANT
A. Ideal Gas Law
Merge the Combined Gas Law with Avogadro’s Principle: PV nT PV T
= k
= R V n
UNIVERSAL GAS CONSTANT
R= Latm/molK
R=8.314 LkPa/molK
You don’t need to memorize these values!

5. You can calculate the value…you just have to know if you are using atm or kPa for your pressure.

6. UNIVERSAL GAS CONSTANT
A. Ideal Gas Law
PV=nRT
UNIVERSAL GAS CONSTANT
R= Latm/molK
R=8.314 LkPa/molK
You don’t need to memorize these values!

7. C. Ideal Gas Law Problems
Calculate the pressure in atmospheres of mol of He at 16°C & occupying 3.25 L.
GIVEN:
P = ? atm
n = mol
T = 16°C = 289 K
V = 3.25 L
R = Latm/molK
WORK:
PV = nRT
P(3.25)=(0.412)(0.0821)(289)
L mol Latm/molK K
P = 3.01 atm

8. C. Ideal Gas Law Problems
Find the volume of 85 g of O2 at 25°C and kPa.
GIVEN:
V = ?
n = 85 g
T = 25°C = 298 K
P = kPa
R = dm3kPa/molK
WORK:
85 g 1 mol = 2.7 mol
32.00 g
= 2.7 mol
PV = nRT
(104.5)V=(2.7) (8.315) (298)
kPa mol dm3kPa/molK K
V = 64 dm3

9. P. 455: #26.
Determine the Celsius temperature of 2.49 mol of a gas contained in a 1.00-L vessel at a pressure of 143 kPa.