1. Pre-AP Chemistry, Mr. Guerrero
Combined Gas Laws
Pre-AP Chemistry, Mr. Guerrero

2. Combined Gas Laws- used when there is a change to PV or T:
P1V1 = P2V2 Boyle’s Law
Combined Gas Law
P1V1 = P2V2 V1 = V2 Charles’ Law T T T T2
P1 = P2 Gay-Lussac Law
T T2

3. Identify the Gas Law and solve each:

4. 355 mL of Ne gas are at 355 K and exert 2. 35 atm of pressure
355 mL of Ne gas are at 355 K and exert 2.35 atm of pressure. What pressure will it exert at 288 K and 368 mL?

5. A 1. 25 dm3 balloon exerts 795 torr. It then expands to 1. 85 dm3
A 1.25 dm3 balloon exerts 795 torr. It then expands to dm3. What is the final pressure?(Assume constant temperature)

6. A steel tank of air exerts 395KPa at 25oC
A steel tank of air exerts 395KPa at 25oC. At what temperature does it exert 462KPa?

7. A piston contains 5. 75 Liters of oxygen gas at 25oC
A piston contains 5.75 Liters of oxygen gas at 25oC. What volume will it occupy at -36oC?

8. 85. 5 mL of CO2 gas are at STP. What pressure will it exert at 100
85.5 mL of CO2 gas are at STP. What pressure will it exert at 100.oC and compressed to 50.0 mL?

9. Day 2

10. A sample of He at 38oC, is heated to 95oC and now occupies 75. 0mL
A sample of He at 38oC, is heated to 95oC and now occupies 75.0mL. What was the original volume? Identify the gas law:

11. Dalton’s Law of Partial Pressures-if different gases are mixed together, the total pressure of the mixture equals the sum of the partial pressures. Dalton’s Law: Ptotal = P P P3….
Partial Pressure- the pressure exerted by an individual gas in a mixture, as if it were the only gas in the container.

12. A gas mixture the following partial pressures: 1. 00 atm Ar, 3
A gas mixture the following partial pressures: atm Ar, 3.00 atm Kr, 2.00 atm CO2.
What is the total pressure?
What gas is present in the least and greatest amount?
What is the mole fraction of each?

13. Wet Gas- A gas collected by bubbling through water
Wet Gas- A gas collected by bubbling through water. A wet gas is not pure, it contains water vapor, it is a gas mixture. The following picture shows how to collect a wet gas in the lab:

14. A sample of O2 is collected over water
A sample of O2 is collected over water. The total pressure of the wet O2 is 785 torr. What is the pressure of the dry O2?(VPH2O = 24 torr)
What is the mole fraction of the O2 & H2O?

15. (Review Q.) How many grams NH3 are in a wet NH3 gas(VPH2O= 16 torr) 425 mL at 158K at 795 torr?

16. (Review Q.) Compare the relative rates of diffusion of carbon dioxide and nitrogen gas