VOLUME AND TEMPERATURE:
CHARLES’S LAW
13.1: Pgs. 450 - 454
Jacques Charles (1746-1823)
First person to fill a balloon with hydrogen gas
Made the first solo balloon flight
His main discovery is shown in the graph…
Plots of V (L) versus T (°C) for several gases.
Volume increases
when the
temperature
increases
Direct
T
relationship, as
,V
Charles’s Law
Charles’s Law:
T
V1 V2
T1 T2
is in Kelvins
CANNOT CHANGE the pressure or amount of gas
It
tells us that the volume of the gas is directly proportional
to the temperature on the Kelvin scale
Plots of volume versus temperature
As we cool gases, they
eventually liquefy
If
we extend a straight
line back, ALL lines
reach zero volume at 273 oC
This suggests that
-273oC is the lowest
possible temperature
Absolute Zero and the Kelvin Scale
Lord Kelvin proposed a new temperature scale
based on this discovery
Kelvin
(K) scale:
1
K same size as 1 degree C, but zero point changed to
-273oC and became 0 K (not degrees)
260oC becomes ___ K?
13K
0 K is lowest temperature theoretically possible
Absolute
All
zero represents zero kinetic energy
motion stops theoretically
Example
A balloon inflated in a room at 24oC has a volume
of 4.00L. The balloon is then heated to a
temperature of 58oC. What is the new volume if
the pressure remains constant?
If a sample of gas occupies 6.80L at 325oC, what
will be its volume at 25oC if the pressure does not
change.
Gay-Lussac’s Law
Studies the relationship between pressure and
temperature
“The pressure of a gas is directly proportional to the
Kelvin temperature if the volume remains constant”
P1 P2
T1 T2
Example
The gas left in a used aerosol can is at a pressure
of 103 kPa at 25oC. If this can is thrown onto a
fire, what is the pressure of the gas when its
temperature reaches 928oC?
The pressure in an automobile tire is 198 kPa at
27.0oC. At the end of a trip on a hot sunny day, the
pressure has risen to 225 kPa. What is the
temperature of the air in the tire? (Assume the
volume has not changed.)
0
