1. Topic: Charles’ Law Do Now:
If all of the flasks are the same in size, temperature, and contain the same number of particles, in which flask will they be moving the fastest?
Which will have the greatest pressure?

2. Temperature Changes & Matter
Solids & Liquids expand/contract as temperature changes
usually very small change
Gases show large volume changes with temperature changes

3. Balloons can expand & contract with the gas

4. Jacques Charles Balloonist
1787 did experiments showing how volume of gases depends on temperature

5. How do hot air balloons work?

6. Relationship between V and T
Constant: Pressure & # moles are constant
At high temp, gas particles move faster and collide with walls more often
Pressure is constant, so volume has to increase

7. Data for Volume-Temperature
202
300 5
167
200 4
132
100 3
114 50 2 10 1
Volume (mL)
Temperature (C)
Trial

9. Charles’ Law: Graphically
Plot V vs Kelvin T
Straight line passing through 0rigin
relationship between V & T is direct

10. Charles’ Law: Verbal
volume of gas at constant pressure varies directly with its absolute temperature
(note: when we’re talking about absolute temperature we mean Kelvin scale!!!!)

11. Charles’ Law: Mathematically V = k T
V1 = V2
NOTE: Temperature must be converted to Kelvin!!!

12. Flash Back….what is the equation for Boyle?
P 1V1 = P2V2
Is this a direct relationship?

13. Problem 1 150 mL of a gas at constant pressure
Temperature increases from 20˚C to 40˚C
What is the new volume?
Step 1: Convert T1 and T2 to Kelvin
Step 2: V1 = V2 becomes 150ml = V2
T T K K
Step 3: Rearrange and solve
313K x 150ml = V2
293K