MHS Chemistry
Heat of Fusion of Ice

Purpose
In this lab you will calculate the energy required to change one gram of ice to water at its melting point (0 °C).  This is also the energy that must be removed from one gram of water at its freezing to point to change it ice.  This quantity is known as "the Specific Heat of Fusion of Ice," and has the symbol  DHf,ice.

Materials
 lots of ice 2 thermometers calorimeter graduated cylinder

Procedure

1. Let the tap water run hot for a few minutes to get the hottest possible water coming out.  Record the mass of the empty calorimeter cup, and the mass of the same cup with about 200 mL of hot water in it.  Place a thermometer in the cup and wait until the temperature steadies.
2. Obtain about 50 g of ice.  That's about 1/2 a handful.  Make sure it has a minimal coating of water from melting.
3. Record the temperature of the hot water immediately before adding the ice.  Record the temperature every five seconds until it has been constant for 25 sec.  What is the final temperature?
4. Measure the final mass of the mixture and cup.
5. Repeat for a total of three good trials.
Data
Organize your data into a proper table in your notebook.  When you are satisfied that it is complete, copy it onto a clean sheet to pass in as part of your lab report.

Calculation
Remember that the general formula for heat transferred is        q = mDTCp

Also remember that when a warmer material is in contact with a cooler one, heat flows from the warmer to the cooler until they are the same temperature.  Assuming these two materials are in contact with nothing else, then the quantity of heat lost by the warm stuff (qwarm) must be exactly equal and opposite to the quantity of heat gained by the cool stuff (qcool).  This lab examines the extra step:  since the cool thing had to melt first, then qwarm is equal to the heat needed to melt the ice PLUS the heat needed to warm up up the newly liquid water (qmelt + qcool).

qmelt + qwarm up + qcool down = 0

For each trial, use your data to calculate qmelt and DHf, ice (which is qmelt/mass).
Calculate an average DHf, ice.
Look up the accepted value of DHf, ice.