Lecture Demonstrations Laboratory

The Demonstrations Manual

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Thermal Properties Of Matter
Heat And The First Law
Change Of State: Thermocouple in Ice; Boiling by Cooling; Boiling by Reducing Pressure; Phase Change in Iron
Kinetic Theory
Gas Law
Entropy And The Second Law

Thermocouple in Ice

Purpose:

To demonstrate phase changes of water and the concept of latent heat.

Procedure:

Thermocouple is frozen in a block of Ice. The Ice block is placed in a 1L beaker filled with ice cold water to 300ml. The thermocouple is connected to Pasco interface and temperature change with time graph is displayed on the screen. Heat is applied until ice melts and water is further heated to the boiling point, to release water vapor.

On the graph can be observed temperature rising to 0C and holding flat until ice is melted, because of the latent heat of fusion. After that temperature will rise to and stay at 100C, because of the latent heat of vaporization.

Hints:

!! This demo should be requested at least a day before it is needed. It takes time to prepare the ice block!!

Using liquid nitrogen and glass Dewar, ice can be cooled down to -30 deg. Celsius.

Typically takes about 25 minutes from start to finish.

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