4C20.54 - Latent Heat of Fusion

Code Number:
Demo Title:
Latent Heat of Fusion
Latent Heat, Heat of Fusion
Area of Study:
Heat & Fluids
Ice, Water, Wax, Thermometer, Hot plate, and Computer with Interface.

Place some wax into a beaker and melt it on a hot plate. Take the beaker off the hot plate and place a thermometer into the melted wax. Monitor the temperature as the wax cools and solidifies. A plateau in the cooling curve should be observed. It is good to melt the wax before class and let it cool to about 70 degrees C to start the class. The fusion plateau will be around 58 degrees C but the experiment will need to run at least 30 to 40 minutes to see good data.

The same experiment may be done using ice instead of wax. Make a small dry ice/alcohol bath in a Styrofoam cup. Put water into a test tube, insert the thermometer, and place into the dry ice/alcohol bath until all the water has frozen. In particular make sure that ice has developed around the thermometer. CAUTION: Do not leave the test tube in the dry ice/alcohol bath too long as a hard freeze will cause the test tube to break. The ice will be at a temperature below 0 degree C at this point. Wait till the temperature reads 0 degrees C before you proceed to the next step. Once the temperature is at 0 degrees C, place the test tube in a warm beaker of water and start the data collection. Note that the water level of the beaker of warm water should only come to a level that is below the tip of the thermometer in the test tube or convection from the sides of the test tube will give discrepant data results. Allow at least 20 minutes of class time for the data collection and results.

Other substances that would work are:

Coconut Oil, melts at 24 degrees C, (76 degrees F).

Hydrogenated Coconut Oil, melts at 36 to 40 degrees C, (97 to 104 degrees F).

Margarine or Crisco.

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