CHARLES’ LAWA gas in a closed system at a constant

pressure, the temperature and the volume are directly proportional.

CHARLES’ LAW

• Directly proportional means that as the temperature increases, the volume increases.

• Or as the temperature decreases the volume decreases.

• Mathematically: V1 V2 T1 T2

CHARLES’ LAW

• The balloon in the picture has a volume of 0.5 liters at a room temperature of 22oC.

• What will the volume of the balloon be if put into some liquid nitrogen?

• The liquid nitrogen is at -196oC.

KELVIN

• Before doing anything, you must convert the temperatures to the Kelvin scale.

• K = C +273• K = 22 + 273 = 295 K• K = -196 +273 = 77 K

• Now you can plug the numbers into the Charles’ law equation.

The volume goes down, down, down!

0.5 L V2_

295 K 77 K

Cross Multiply

295 V2 = 38.5

V2 = 0.13 liters

Practice Makes Perfect

• Practice Problem #1:• A container with a

volume of 148ml is at standard temperature. If the container is heated to 500 K, what is the new volume?

• Standard Temperature: 0oC = 273 K

• Practice problem #2:• A syringe is set at 7ml at

a temperature of 25oC. If the volume is increased to 9ml, what is the new temperature?

• Work these problems on your paper and then check your answer.

How did you do?

• Practice problem #1, the answer is 271ml

• Practice problem #2, the answer is 110oC. (To get the correct answer, you had to convert 25oC to 298 K, the answer is also 383K)

• Practice problem #3:• A basketball is inflated

to 3.5 liters with an air temperature of 40oC. When the basketball is taken outside, the volume drops to 3.1 liters. What is the temperature outside?

The answer is 4oC

Now it is time to move on to

DALTON’S LAW

DALTON’S LAW

The sum of the partial pressures is equal to the

total pressure.

DALTON’S LAW

• The two containers have equal volume.

• The containers are connected by a hose, but the valve is closed.

DALTON’S LAW

• The container on the left has a pressure of 500mm Hg.

• The container on the right has a pressure of 300mm Hg

DALTON’S LAW

• If all of the gas from the left container is pushed into the right container, what is the total pressure of the gas?

• P1 + P2 + … = Ptotal

DALTON’S LAW

• The total pressure is now 800 mmHg.

• The sum of the partial pressures is equal to the total pressure.

• Let’s try one practice problem.

P1 + P2 + … = Ptotal• A 2 liter container has a gas with a pressure of

1.04 atm. Another 2 liter container has a gas with a pressure of 760mm Hg. If the two containers are combined into one 2 liter container, what is the total pressure?

• Hint: Be consistent with units.

2.04 atm

• The easiest way to solve this problem is to convert 760mm Hg to 1atm.

• From there, it is simple:

1.04atm + 1atm = 2.04atm