Charles’s Law
Charles’s Law basically says that for an ideal gas if the temperature (in Kelvins) increases by a certain factor,
the volume will increase by that same factor. So if the temperature doubles, the volume will also double.
The formula for Charles’s Law is:
V1 = V2
T1 = T2
Temperature is measured in Kelvin for this law.
Ex: Suppose you want to fly a balloon over a small mountain. You fill the balloon with 600 L of air at 27
0Celsius. You know that at the highest point of your trip, the temperature will drop to 12 0Celsius. You want to
know what will happen to the volume of the balloon at this point.
So the variables are:
V1 = 600 L
First, you change degrees Celsius to Kelvin:
T1 = 27 0C + 273 = 300 K
T2 = 12 0C + 273 = 285 K
Second, you solve the equation for V2 and you see that:
V2 = V1T2
so you plug in the numbers:
V2 = (600L)(285K)
T1
300K
Therefore, the volume at the highest point will be 570 L. As the temperature drops, the gas molecules slow
down, so the volume also drops.
Problem
Work
1) A birthday balloon is inflated to a volume of 2.0 V1=
liters in a refrigerated truck at -66 0C. The
T1=
balloon is delivered to an outdoor birthday
V2=
party. During the heat of the day, the
T2=
temperature reaches 37.5 0Celsius. What is the
new volume of the balloon at this temperature?
(4 pts)
2) A tire is inflated on a hot day (47 degrees
V1=
Celsius) in Arizona. The volume of gas pumped T1=
into the tire is 40 liters. Then the car is driven
V2=
north, to Montana, where there is still snow on
T2=
the ground. The tire looks flat. The volume in
Montana is measured to be 34 liters. What is
the temperature in Montana? (give the
temperature in degrees Celsius). (5 pts)
3) You have a can of hairspray that holds 0.5
V1=
liters of gas. The gas is at standard
T1=
temperature. If you heat up the can (incinerate
V2=
it) to 273 0Celsius, what will happen to the
T2=
volume of the gas? (4 pts)
4) What is the new volume of a gas that started
out at 400 Kelvin and 50.0 liters, but was
cooled to –73 0Celsius? (4 pts)
5) Jacques Charles believed that if you could cool
a gas down to absolute zero it would have no
volume. But if you cool a gas significantly it will
become a liquid before it reaches absolute
zero. Chlorine, for example, condenses into a
liquid at –50 0C. If you start out with 6.2 L of the
gas at standard temperature, what volume
would it occupy at its boiling point? (4 pts)