1. There are 8 questions total.
Gas Problems?
How about gas LAW problems? Take out a piece of lined paper and answer the numbered questions with a yellow star by them. The answers are behind the colored circles in each slide.
There are 8 questions total.

2. Charles’ Law Constants are Variables are Direct relationship
# of particles
Pressure
Variables are
Temperature
Volume
Direct relationship
Equation is: V1 = V2
T T2

3. Boyle’s Law Constants are Variables are Indirect relationship
# of particles
Temperature
Variables are
Pressure
Volume
Indirect relationship
Equation is: P1V1 = P2V2

4. GayLussac’s Law Constants are Variables are Direct relationship
# of particles
Pressure
Variables are
Temperature
Volume
Direct relationship
Equation is: P1 = P2
T1 = T2

5. Standard Temperature & Pressure (STP)
There are standard values for temperature and pressure
The reason is that it creates consistent conditions for scientists to compare their results.
Standard Temperature
0°C (K = °C  273K)
Standard Pressure: The following are equivalent
1 atm = 760 torr = 760 mm Hg
Standard Volume:
22.4L in a mole of any gas at STP

6. MIXED PROBLEM PRACTICE
Do the following steps for EACH problem
Identify the law needed to solve the problem (Charle’s, Boyle’s, Gay-Lussac’s)
Identify whether it’s a direct or inverse relationship
Solve the problem

7. 1. A gas at 45°C and 1. 2 atm is cooled to a temperature of 5°C
*1. A gas at 45°C and 1.2 atm is cooled to a temperature of 5°C. What is the new pressure of the gas?
Set this up and work it before you check it on the next slide.
T1 = T2 =
P1 = P2 = ?

8. *2. A 2.3L sample of gas under 500 torr of pressure is allowed to expand with a final pressure of 2.3 atm. What is the final volume?
**Notice both torr and atm are used so multiply the 2.3 by 760 torr using factor label…
V1 = V2 = ?
P1 = P2 =

9. *3. A gas at a pressure of 700 torr is pressurized to 1200 torr and 50°C. What was the initial temperature of the gas in degrees Celsius – You will get your answer and then subtract 273 to go from K to °C?
You will need to find it in Kelvin first.
T1 = ? T2 =
P1 = P2 =

10. *4. A syringe containing 5.5 mL of gas at standard temperature is allowed to expand to twice its volume. What is the final temperature?
What is twice the 5.5mL?
V1 = V2 =
T1 = T2 = ?

11. * L of a gas at standard pressure is shrunk to a volume of 12.5L. What is the new pressure, in torr?
V1 = V2 =
P1 = P2 = ?

12. The combined gas law:
If all three of these variables P, V and T are changed in a new set of conditions (for instance STP) and 5 of the six variables are known, the sixth can be calculated using….THE COMBINED GAS LAW
P1V1 = P2V2
T T2

13. 6. How would the pressure of 11. 2 L of gas at STP change in a 10
*6. How would the pressure of 11.2 L of gas at STP change in a 10.0L container at 298K?

14. 7. What is the initial pressure in a 15. 0L tank at 40
*7. What is the initial pressure in a 15.0L tank at 40.0 C that contained 2550L of propane (C3H8) at STP? – (This is a problem to grill out in the parking lot on a warm spring day!)

15. 8. Calculate the volume of a gas at STP that occupies 255mL at 2
*8. Calculate the volume of a gas at STP that occupies 255mL at 2.2 atm in a lab that is 25.5 degrees C.