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?
Temperature Changes &
Matter
Solids & Liquids expand/contract as
temperature changes
– usually very small change
Gases show large volume changes with
temperature changes
Balloons can expand & contract with the gas
Jacques Charles
Balloonist
1787 did
experiments
showing how
volume of gases
depends on
temperature
How do hot air balloons work?
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
Data for Volume-Temperature
Trial
Temperature (C)
Volume (mL)
1
10
100
2
50
114
3
100
132
4
200
167
5
300
202
Charles’ Law: Graphically
Plot V vs Kelvin T
Straight line passing through 0rigin
relationship between V & T is direct
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!!!!)
Charles’ Law: Mathematically
V = k
T
V1 = V2
T1
T2
NOTE: Temperature must be
converted to Kelvin!!!
Flash Back….what is the equation
for Boyle?
P 1V1 = P2V2
Is this a direct relationship?
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
T1 T2
293K
313K
Step 3: Rearrange and solve
313K x 150ml = V2
293K