Charles’ Law

This activity is designed to confirm Charles’ law through an actual experiment.

Theory

Increasing the temperature of a gas causes the molecules that make up the gas move faster. The pressure within the container that holds the gas is determined by the number of collisions between the molecules and the walls of the container, and by the velocity of the molecules when they collide with the walls. If pressure remains constant and temperature increases, the gas expands, which reduces the number of molecular impacts with the container walls and negates the increase in molecular velocity.

Charles’ Law states that the thermal expansion of rarified gas of constant pressure is proportional to the increase in temperature, and is represented by the expression shown below. If the temperature when the volume of gas reaches zero is defined as absolute zero, absolute zero is –273°C.

V = 273V0 (T + 273)

V(m3) : Gas Volume

V0(m3) : Gas Volume at 0°C

T (°C) : Gas Temperature

1Absolute Zero

2-4-1

English

Activity:tivity: SetupSetup

￿ Equipment

Syringe (with scale markings)

Plastic Container

Rubber Tube

Rubber Gasket

Clip

Mixing Stick

Warm Water, Cold Water, Ice

Temperature Measurement Setup (EA-200, graphic scientific calculator, data communication cable, temperature probe)

￿Assembling the Equipment

uCut a hole into the side of the plastic container, and affix the rubber gasket around the hole on the outside of the container.

uSlip the syringe with the rubber tube on its tip into the hole, and pack it with rubber to make it watertight.

uAffix the clip to the rubber tube to seal the air inside the syringe.

1 Plastic Container

2Rubber Gasket

3Rubber Tube

4Syringe

5Hole

6Clip

￿Setting Up

uFill the plastic container with warm water and wait until the air in the syringe stabilizes.

1Plastic Container

2Warm Water: 60°C

3Mixing Stick

4Temperature Probe (CH1)

5EA-200

20020601