PERFORMANCE ASSIGNMENT                          Lab Ten

Energy Needed to Melt Ice


Water changes from ice to a liquid at zero degrees celsius. Determine the energy required to melt one grams of ice by letting an excess of it interact with warm water in a styrofoam cup. The energy given up by the water as it cools is the energy used to melt the ice.

Objectives

1. Determine energy gained by ice. This is a gain in Potential Energy
2. Determine energy lost by the warm water. This is a loss in Kinetic Energy
3. Calculate the accuracy of your work.
4. Calculate the error.

Procedure

1.

Warm about 125 ml of water to about 50 C.

2.

Measure 100 ml of water into the styrofoam cup record the temperature of the water to the nearest 0.1 C.

3.

Obtain several ice cubes and damp the excess water from them. Place the ice in the warm water and stir until the temperature is about 0 C. Add more ice if needed to cool the water and record the lowest temp.

4.

Remove any unmelted ice with tongs. Be sure to drain as much water as possible back into the cup.

5.

Measure the volume of water remaining to the nearest milliliter.


Data

initial volume of water in cup

 

initial temp of warm water

 

lowest temp of water

 

final volume of water

 

Calculations

1. Determine the moles of ice melted (dH2O = 1g/1ml)



2. Find the energy gained by the ice. q = n ice x 6025 J/mol



3. Determine the change in temp for the water



4. Calculate the energy released by 100 grams of water. q = mwater (4.18 j/mol*K) T



5. The energy gained by the ice should equal the energy lost by the warm water.
Divide the smaller number by the bigger number, this is the accuracy of your work.



6. Calculate the error by subtracting the percent accuracy(above) from 100%.



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