1. Warm-Up
What causes gas particles to exert a pressure on their containers?

2. Warm-Up
Why doesn’t the size/mass of gas particles affect the pressure they exert on their container?

3. Warm-Up Get out your pink reference sheet.
What is considered to be Standard Temperature & Pressure (STP)? (List ALL of the T and P values)
Write an equation to convert from Celsius to Kelvin
Convert 30°C to Kelvin

4. The Ideal Gas Law

5. Real Gases
Real gases deviate from ideal behavior (Kinetic Molecular Theory) at high pressures and low temperatures.
At high pressures, the volume of the actual gas particles becomes noticeable, so they become more difficult to compress
At low temperatures, the kinetic energy of the gas particles is so small that they begin to clump together and form liquids

6. Ideal Gas Law
This law mathematically explains all the properties of an ideal gas (obeys KMT)
PV = nRT
P = Pressure (any units)
V = Volume in liters (L)
n = #of particles in moles (mol)
R = Ideal gas constant
Units must match pressure
T = Temperature in Kelvin (K)

7. Practice
How many moles of a gas at 100oC does it take to fill a 1.00-L flask to a pressure of 1.50 atm?
Make a list:
P =
V =
n =
R =
T =

8. Practice What is the volume occupied by 9.45 g of C2H2 at STP?
Make a list:
P =
V =
n =
R =
T =

10. Combined Gas Law P 1 V 1 T 1 = P 2 V 2 T 2 n is constant
This law explains what will happen to an ideal gas when you change its conditions.
P 1 V 1 T 1 = P 2 V 2 T 2
n is constant
1 represents the initial conditions
2 represents the final conditions
P, V, and T units much match each other!

11. Practice
At conditions of 785 torr and 15.0oC, a gas occupies a volume of 45.5 mL. What will be the volume of the same gas at 745 torr and 30.0oC?
Make TWO Lists:
P1 =
V1 =
T1 =
P2 =
V2 =
T2 =

12. Practice
On a cold morning (10.0oC), a group of hot-air balloonists start filling their balloon with air, using a large fan. After the balloon is 75% filled, they turn on the propane burner to heat the air. At what Celcius temperature will the air completely fill the balloon to its maximum capacity of L?
Make TWO Lists:
P1 =
V1 =
T1 =
P2 =
V2 =
T2 =

13. Dalton’s Law of Partial Pressure
Particles of different gases in a mixture act independently
The total pressure of a mixture of gases will equal the sum of the pressures exerted by each gas
PT = P1 + P2 + P3 + …

14. Practice
A person using an oxygen mask is breathing air with O2 at a pressure of 36 kPa. What is the partial pressure of the N2 when the air pressure in the mask is 110 kPa?
Make a list:
PT =
P1 =
P2 =

15. Warm-up
What is the volume of 5.3 moles of an ideal gas at 42°C and a pressure of kPa?

16. Warm-Up (don’t write the prompt)
A chemist might commonly perform the following reaction in a chamber at 327oC under a pressure of mmHg. How many grams of ammonia would be produced from liters of hydrogen gas at the above conditions?
3 H2 + N2  2 NH3