Scientist:
Per:
Date:
UNIT 7: THERMOCHEMISTY
____________________
_________
_________
LAB 7.2
HEAT OF FUSION OF WATER
Safety:
Although there are no significant safety concerns in this lab, appropriate lab behavior
and attention to instruction and lab procedure is always required.
The only chemicals are water and ice. There is no heat
Disposal:
Water can go down the sinks. Trash in the trash can.
Purpose
The purpose of this experiment is to determine the amount of heat to melt 1 gram of ice into liquid
water. This energy is referred to as the heat of fusion (ΔHfus).
Materials
Styrofoam cup, paper towel, thermometer, ice, plastic spoon, balance
Procedure
1. Mass an empty cup and record your answer below.
2. Fill the cup half full of water and measure the mass. Record below.
3. Put your thermometer into the cup of water. Record the temperature as the
initial temperature.
4. Pat dry several small ice cubes and immediately put them in the cup. Stir
with your plastic spoon and record the initial temperature.
5. Add ice as needed until the temperature drops to approximately 0oC.
6. When the temperature stops falling (approximately 0oC) record the final
temperature and quickly remove the remaining ice with your spoon. Pour any
water left in your spoon back into the cup.
7. Mass the cup of water and melted ice and record.
Hypothesis
How can we determine the heat of fusion of water? What scientific principles must we consider?
If ice is added to water, then the energy required to melt the ice can be accurately determined from the
temperature change of the water because________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
Data
mass of empty cup = ______________
mass of cup & water = _______________
mass of cup & water & melted ice = _________
initial temperature = _______________
final temperature = _____________
Analysis
Show your work!
1) Calculate the original mass of the water:
2) Calculate the mass of the melted ice:
3) Given the specific heat of water (4.2 J/goC), calculate the energy lost by the
original water:
4) Since the heat ___________ by the water = the heat used to __________
the ice, the heat of fusion of ice (ΔHfus) can be calculated by taking the heat
lost by the water (calculated above) and dividing by the mass of the melted ice.
ΔHfus =
5) Obtain the correct value for DHfus of ice from your teacher and calculate your
percent error using the equation:
% error = experimental value - accepted value x 100
accepted value
6) Identify at least 2 sources of error in this lab.