Description:

Ice cubes melt at different rates depending on the thermal conductivity of the material they are resting upon.

Watch Video:

Other Demos of Interest:

 Heating Water in a Balloon Thermal Conductivity How a Radiometer Works

Possible Incorporated Topics:

• heat
• thermal properties of materials
• phase change

Theory:

Thermal conductivity is a material’s ability to conduct heat. It describes the rate at which heat is transferred by the material; a higher thermal conductivity means the material conducts heat at a faster rate.

Two materials that are the same temperature may feel hotter/colder than one another to the touch if they have different values of thermal conductivity. For example, a piece of copper at 30°C will feel warmer to the touch than a piece of styrofoam at the same temperature. This is because copper is a better conductor than styrofoam and has a higher value of thermal conductivity. Heat is transferred to your hand by the copper at a faster rate than it is by the styrofoam so it feels warmer.

The two materials featured in this video are plexiglass are aluminum. The value of thermal conductivity of aluminum is 205 W/mK, while the thermal conductivity of plexiglass is ~0.2 W/mK.  Even though they are both at the same temperature, the aluminum melts the ice faster than the plexiglass because it has higher thermal conductance. Heat is transferred from the table to the ice at a faster rate by the aluminum.

Apparatus:

• piece of aluminum
• piece of plastic
• ice cubes

Procedure:

• place an ice cube atop the piece of the aluminum and place another ice cube atop the piece of plastic
• watch as the ice cube atop the aluminum melts much faster than the ice cube atop the plastic