1. Charles Law

2. At higher temperatures, the particles in a gas have greater kinetic energy.
The volume of a gas is directly proportional to temperature when the pressure (P) and number of moles (n) are constant. T V T V
To be an accurate direct proportion, the line must go through the origin
volume
temperature
V1 = V2
T T2

4. New Temperature Scale Kelvin K = °C + 273
This new scale allows a direct proportion and no need for negative temperature values
MUST USE FOR ALL GAS LAWS!!
Standard temperature

5. Absolute zero Zero kelvin Lowest temperature possible
All molecule motion stops
Never been achieved

6. Ex. A sample of helium occupies 473 cm3 at 36°C
Ex. A sample of helium occupies 473 cm3 at 36°C. What will be the volume when temperature is increased to 94°C?
V1= 473 cm3
T1 = = 309 K
V2 = ?
T2 = = 367 K
V1 = V2
T1 T2 V2
(473 cm3) =
(309 K)
(367 K)
(473 cm3)(367 K) =
(309 K)V2
V2 = 562 cm3
(309 K)
(309 K)

7. Combined Gas Law

8. Put Boyle’s and Charles’ Law together to make the Combined Gas Law
P1V1 =
P2V2 T1 T2

9. Ex. A gas has a volume of 7. 84 mL at 71. 8 kPa and 25. 0°C
Ex. A gas has a volume of 7.84 mL at 71.8 kPa and 25.0°C. What will be the volume at STP?
P1 = 71.8 kPa
V1 = 7.84 mL
T1 = = 298 K
P2 = kPa
V2 = ?
T2 = = 273 K
P1V1 =
P2V2 T1 T2
(71.8 kPa)(7.84 mL) =
( kPa)V2
298 K
273 K
(71.8 kPa)(7.84 mL)(273 K) =
( kPa)(273 K)V2
( kPa)(298 K)
( kPa)(273 K)
V2 = 5.09 mL