TITLE – DETERMINING THE HEAT OF FUSION OF ICE
(or THE “WATCH ICE MELT” LAB)
(Lab Guidelines: 1,2,3,4,5&6[include handout],7, 9-11,12)
PURPOSE – To determine how much heat energy is required to melt 1 gram of ice and 1
mole of ice.
BACKGROUND INFO – What is specific heat (C)? What is heat of fusion (Hf )?
How do I use Q = CmT? How do I use Q = Hfm?
What does the phrase HEAT GAINED = HEAT LOST mean?
MATERIALS – balance, foam cup calorimeter, thermometer, water, ice cubes
PROCEDURE
1. Determine the mass of your empty foam cup.
2. Fill the cup about 1/2 to 2/3 full with water.
3. Determine the mass of the cup with water.
4. Determine the temperature of the water in the cup.
5. Place a few ice cubes in the cup. Make sure that the water level of the cup does not
rise too high or you might lose some water during the lab.
6. Stir the ice water mixture constantly, and record the temperature of the water in the
cup right at the moment when all the ice has completely melted.
7. Determine the mass of the cup, water, and melted ice.
8. Repeat this procedure a second time with new samples of water and ice.
DATA – Create a data table to record all important data. Read the procedure closely in
order to help you with this!!
CALCULATIONS / QUESTIONS / ERROR ANALYSIS
For #’s 1,2,4,5,7 perform calculations for both trials.
1. Calculate the mass of room temperature water that was in your cup at the start of your
lab.
2. Calculate the temperature change experienced by this water.
3. Did this water gain energy or lose energy during the course of the lab. Explain.
4. Calculate the heat lost by this water using Q=CmT.
5. Calculate the mass of ice, which you added to the cup.
6. What happened to the ice over the course of the lab? What substance provided the ice
with the necessary heat energy to undergo this transformation?
7. Using your values from #4 and #5, calculate the heat of fusion of ice in joules of heat
per gram of ice melted.
8. Calculate your average value for the heat of fusion of ice.
9. The actual value for the heat of fusion of ice is 334 J/g. Calculate your percent error
for your value in #8.
10. Recall that the specific heat of liquid water is 4.18 J/gC. Notice that C does not
appear in the units for heat of fusion of ice (334 J/g). Why are C absent in the units for
heat of fusion?
11. Now compare the values for the specific heat of water (4.18 J/gC) and the heat of
fusion of ice (334 J/g) by answering this question. Which requires more energy – melting
1 gram of ice or raising the temperature of 1 gram of water by 1 C. Explain.
12. Using appropriate conversion factors, convert your value from #8 from J/g to kJ/mol
(Hint: how many J are in a kJ, and what is the molar mass of water?) This is your value
for the heat of fusion of ice with more commonly used units of kilojoules per mole.
13. The actual value for the heat of fusion of ice in kJ/mol is 6.02 kJ/mol. Calculate your
percent error for your value in #12.
(NOTE: YOUR ANSWERS FROM #9 AND #13 SHOULD BE IDENTICAL. IF THEY
ARE NOT, GO BACK AND CHECK YOUR WORK.)
14. Discuss some possible errors which might have contributed to your percent error
calculation.
15. Write a one sentence definition of the phrase “heat of fusion.”
16. Use the actual value of 334 J/g for the heat of fusion of ice and the actual value of
4.18 J/gC for the specific heat of water to calculate how many kilojoules (kJ) of heat
energy would be needed to melt a 10.0 lb block of ice and warm the resulting water up to
50 C (Note:1 lb. = 454 grams).
Note: In order to solve this problem, you will have to do two separate problems
(one for the melting of the ice, and one for the heating of the resulting liquid water) and
then add the results of each together.
CONCLUSION -- Don’t forget to write a conclusion.
Here is a great guide for writing your conclusion:
1) Restate the purpose
2) Summarize the procedure
3) Discuss any important principles / equations used
3) Explain the math
4) Report your results