MOLAR HEAT OF FUSION OF ICE
INTRODUCTION
For a particular substance, the conversion from a solid to a liquid is
an endothermic process, whereby energy is absorbed by the system.
The conversion from a liquid to a solid is an exothermic process
whereby energy is released by the system. For a particular
substance, when the state changes from a solidliquid, the direction
of energy flow is opposite but the magnitude of the energy change is
the same. The molar heat of fusion refers to the quantity of energy
released when a substance is converted from a liquid to a solid.
THEORY
In this experiment we will determine the molar heat of fusion of ice.
Your result should approximate the value found on your data table,
6.01kJ/mol.
When using a calorimeter, The First Law of Thermodynamics applies.
Therefore, the heat lost by the calorimeter will equal the heat gained
by the ice. A known quantity of ice will be allowed to melt in a
calorimeter. The water in the calorimeter will decrease in
temperature as energy is utilized to melt the ice cube. The water that
forms from the ice cube will then increase in temperature until the
calorimeter water and the water from the ice cube reach the same
temperature. In the calculations, we must allow for the heat needed
to warm up the ice water that forms from the ice cube.
In performing the calculations, we will make a number of
assumptions. The first assumption is that the ice is at 0oC. The
second is that all of the heat exchanged is with the water contained
within the calorimeter.
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PROCEDURE
1. Use the same balance for all mass determinations.
2. Determine and record the mass of a dry calorimeter apparatus,
including the lid, to the nearest 0.01g. Use this mass for all
trials.
3. Use a hot plate and a 600 mL beaker, to heat approximately
250 mL of distilled water to approximately 30.0oC.
4. Use a 100 mL graduated cylinder to measure 200.0 mL of the
distilled water into the calorimeter. Determine and record the
mass of the calorimeter and contents to the nearest 0.01g.
5. Determine and record the initial temperature of the distilled
water in the calorimeter to the nearest 0.1oC.
6. Obtain one distilled water ice cube. Place the ice cube on a
paper towel and dry it. Place it in the calorimeter. Cover the
calorimeter and stir with the thermometer until the ice cube is
completely melted.
7. Record the final (lowest) temperature of the water in the
calorimeter to the nearest 0.1oC.
8. Determine and record the mass of the calorimeter, the warmed
distilled water and the melted ice cube to the nearest 0.1g.
9. Dry all parts of the calorimeter thoroughly. Repeat the above
procedure at least three times. Reheat the distilled water used
in step 3 again if necessary.
OBSERVATIONS
Much of what happens in this experiment is not visible as it
happens within the calorimeter. Nevertheless, observations are
required and you will need to be creative.
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DATA
The following data table may be used by you or may be modified.
When recording data, it is important to use the precision identified
in the procedure, for all measurements.
SAMPLE DATA TABLE
TRIAL 1
TRIAL 2
TRIAL 3
a. Mass of
calorimeter (to
nearest 0.01g)
b. Mass of
calorimeter and
water (to
nearest 0.01g)
c. Initial
temperature of
calorimeter (to
nearest 0.1oC)
d. Final
temperature of
calorimeter (to
nearest 0.1oC)
e. Mass of
calorimeter,
water and
melted ice (to
nearest 0.01g)
CALCULATIONS
You will do a set of calculations for each trial above and then
average the results.
In order to perform the calculations for this experiment, you will
need to manipulate the data to isolate the required data. The table
below will help with this process.
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TRIAL 1
TRIAL 2
TRIAL 3
Mass of water
in calorimeter
(to nearest
0.01g): from
data table b-a
Mass of ice in
calorimeter (to
nearest 0.01
g): from data
table above e-b
Change in
temperature of
calorimeter
water (to
nearest 0.1oC):
from data table
above d-c
Change in
temperature of
the water that
forms from the
ice cube
melting (to
nearest 0.1oC):
From data
table above d-0
The equation for the calculation is the following:
nH = m1c1∆t1 – m2c2 ∆t2
where:
n= mole of ice
m1= mass of water in the calorimeter
c1 = specific heat capacity for water
∆t1 = temperature change for the water in the calorimeter
m2 = mass of the ice cube
c2 = specific heat capacity for water (note this is the water
that formed from the ice cube)
∆t2=temperature change for the water that formed from
the ice cube
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CONCLUSION
In your conclusion, provide an overview of the lab process and
compare your results to the book value for the Molar Heat of Fusion
of Ice.
REASONS FOR ERROR
Indicate any reasons for error that may be associated with this lab
and your results.
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