Heat of Fusion of Ice
(Reference: Kevin Anderson, Chemistry teacher, Lake Linden High School, Lake Linden, MI, 1998)
Calorimeter apparatus – 1 per group
Ice – enough for all group to use 2 pieces
In a crystalline solid, the molecules are held in a crystalline structure. For a solid to change state and become a liquid, it takes energy to break the bonds between the molecules in the crystal. Once the bonds between the molecules in the crystal have been broken and they are able to slide past each other, the solid has become a liquid.
Generally, for crystalline solids such as ice, there is no increase in temperature during the change of state between solid and a liquid. The heat exchange during the process of melting is only to change the state. The amount of heat required for one gram of a solid to change state to a liquid is called the heat of fusion.
In this lab, you will measure the heat of fusion of ice.
1. Record the mass and specific heat of the calorimeter cup.
2. Warm some water in a beaker. The reason we warm the water is so it will more quickly melt the ice. Fill the calorimeter cup a little less than half full of water. Record the mass of the calorimeter cup and water.
3. Place the calorimeter cup back into the jacket and cover it. Measure the temperature of the water.
4. Select two medium pieces of ice and dry them. Place them carefully into the calorimeter, being careful not to splash any water out.
5. Stir the water gently until the ice has completely melted and the temperature has stabilized.
6. Record the final temperature.
7. Take the cup out and measure the mass of the cup and water.
|Mass of calorimeter cup||0|
|Mass of cup plus warm water||0|
|Initial temperature of cup and warm water||0|
|Final temperature of mixture||0|
|Mass of cup and mixture||0|
RESULTS AND CALCULATIONS:
|Mass of warm water||0|
|Mass of ice||0|
|Change in temperature for warm water and cup||0|
|Change in temperature for ice water after ice has melted||0|
RESULTS / SAMPLE CALCULATIONS:
1. Calculate the heat lost by the warm water and warm calorimeter cup.
2. The ice undergoes two separate heat changes. First, it absorbs heat in changing from a solid to a liquid. Then, it absorbs additional heat in warming from a liquid at 0°C to the final temperature. Calculate the energy required warming from a liquid at 0°C to the final temperature.
3. Now, use the law of heat exchange to determine the heat gained by the ice in melting.
4. Use the above result to determine the heat of fusion of ice.
5. Calculate the absolute and relative error between your result and a published result. If your result does not agree with the published result, account for any error. Be specific.
TYPE A LAB REPORT, INCLUDING:
(A) An introduction that introduces the theory and the experiment that will be used to test the theory.
(B) A procedure section that explains in a little more detail how the theory was tested.
(C) A results section that gives the primary result. This is where the results are discussed. Percent error from the accepted value is usually included here.
(D) A conclusions section that states whether the results were accurate. In this section, you should explain where error is believed to come from. Be specific. In this lab, there is one certain source of error. I would expect that your result is higher than the accepted value. Why?
(E) The last section of your report is where your sample calculations belong.
· Student solutions can all go down the drain.
Ginger Chateauneuf, 2000.