1. You will need a partner as well as a calculator
The Gas Laws
You will need a partner as well as a calculator

2. Ideal Gas Law
PV = nRT
Boyle’s Law
P1V1 = P2V2
Combined Gas Law
P1V1/T1 = P2V2/T2

3. Pressure
Pressure (P): The force of gas molecules as they hit the sides of the container in which they are placed.
 Units = Atmospheres (atm)
StandardTemperaturePressure = 1atm

4. Temperature StandardTemperaturePressure = 273 K
Temperature (T): A measurement of the amount of energy that molecules have. The higher the energy, the higher the temperature.
Common units of temperature:
Kelvin (K): The ONLY units that can be used when doing numerical problems with gases.
*Degrees Celsius (0C): Must be converted to Kelvin before doing problems (by adding 273).
StandardTemperaturePressure = 273 K

5. Volume Volume (V): The amount of space in which a gas is enclosed.
The most commonly used unit of volume is liters (L).

6. Which tank contains the greatest number of particles?
Number of particles = pressure x volume
10 atm
1 atm
40 atm
25 atm
30 L
60 L
45 L
15 L A B C D

7. Ideal Gas Law
Avogadro’s law: One mole of every gas has the same volume. (22.4 L)
STP = standard temperature & pressure
Standard temperature = 273 K
Standard pressure = 1 atm
All gases behave the same at the same temperature, volume and pressure.
H2O(g), CO2(g), O2

8. Ideal gas law: PV = nRT P = pressure (in atm) V = volume (L)
n = number of (moles) 
R = ideal gas constant L•atm/mol•K
T = temperature (Kelvin) = (oC + 273)

9. “We Do”
If I have 10 liters of a gas at a pressure of 1.5 atm and a temperature of 250 C, how many moles of gas do I have?
P = 1.5 atm
V = 10 L
n = ? moles
R = (always this #)
T = 25oC+ (273) = 298 K

10. PV=nRT (P x V) = (n x R x T) 1.5 x 10 = n x 0.0821 x 298
Divide both sides by so “n” by itself
n = moles

11. “You Do”
If I have 23.5 moles of gas at a temperature of oC, and a volume of liters, what is the pressure of gas?
P =
V =
n =
R = (always this #)
T = ___oC+ (273) =

12. Boyle’s Law
P1V1 = P2V2
****Remember that temperature needs to be in Kelvin (oC = 273K)****
P1 = First Pressure
V1 = Frist Volume
P2 = Second Pressure
V2 = Second Volume

13. “We Do” P1V1 = P2V2
A high-altitude balloon contains L of He has at 10.3 atm. What is the new volume when the balloon rises to an altitude where the pressure is only 2.3 atm?
P1 =
V1 =
P2 =
V2 =

14. P1V1 = P2V2
(10.3 atm) (30.0 L) = (2.3 atm) ( V2)

15. “You Do” P1V1 = P2V2
A gas with a volume of 4.02 L at a pressure of 2.31 atm is allowed to expand to L. What is the new pressure of the gas?
P1 =
V1 =
P2 =
V2 =

16. Combined Gas Law P1V1 = P2V2 T1 T2 P1 = First Pressure
****Remember that temperature needs to be in Kelvin (oC = 273K)****
P1 = First Pressure
V1 = Frist Volume
T1 = First Temperature
P2 = Second Pressure
V2 = Second Volume
T2 = Second Temperature

17. “We Do” P1V1/T1 = P2V2/T2
If I initially have a gas at a pressure of 1.3 atm, a volume of 24.6 liters and a temperature of 214K, and then I raise the volume to 46.0 L and increase the temperature to 286 K, what is the new pressure of the gas?
P1 = P2 =
V1 = V2 =
T1 = T2 =

18. P1V1/T1 = P2V2/T2 (1.5 atm)(24.6 L) = (P2)(46.0 L) 214 K 286 K
0.172 atm L/K = (P2) (0.161 atm/K)
P2 = 1.75 atm

19. “You Do” P1V1/T1 = P2V2/T2
If I have 23.5 L of gas held at STP, what is the volume of gas if I increase the pressure to 45.2 atm and increase the temperature to oC?
P1 = P2 =
V1 = V2 =
T1 = T2 =