Activities for February 18, 2004

Physical Science - FME [Phys 101] Spring 2004

Activities for Wednesday, February 18, 2004.

Last week, we measured the Specific Heats of both Aluminum and Brass. Today, you will be working in your groups to determine the Heat of Fusion of water. Simply put, the Heat of Fusion of water is the number of calories that each gram of ice at 0°C must receive in order to melt to 1 gram of water at 0°C.

[1] Get into your groups, and send someone to the front of the room to get a Styrofoam cup, a graduated cylinder, a funnel, and a thermometer.

[2] Consult the Table below to determine the volume of water that your group will be working with. Use your graduated cylinder to place this volume of water into your Styrofoam cup.

Group	Volume Water (mls)
Car Bombs	80
Group A	75
JRKC	70
Pink Flamingoes	60
Dynamites	50
Team Choir	40

[3] Use your thermometer to determine the temperature of your water. Record this temperature here.

[4] Place your funnel into your graduated cylinder. After you have done so, come up to the front of the room with your Styrofoam cup, water, and thermometer.

[5] John will now add some ice to your cup. As a result, the temperature will immediately begin to fall. Watch the temperature carefully - the instant that it gets to 0°C, pour your water through the funnel into your graduated cylinder, making sure that all of the ice is trapped in the funnel.

[6] Record the total volume of water in the graduated cylinder. By comparing with the initial volume of water that you had, determine the number of grams of ice that melted. Record this here.

[7] The heat that was used to melt the ice obviously came from your room temperature water. Determine the number of calories that flowed out of your water by doing the following:

(i) Realizing that the final temperature of your water was 0°C, determine the number of degrees by which the temperature of your water dropped.

(ii) Multiply this temperature change by the number of grams of water that you started with. This will give the number of calories that flowed out of your water and into your ice.

Record this number here: __________

[8] Finally, divide the number of calories that flowed into the ice by the number of grams of ice that melted. This will give you the number of calories required to melt each gram of ice, and is your group's value for the Heat of Fusion of water. After you have a value, report it to John.
SHAPE \* MERGEFORMAT

After you have finished the above activities, work on the following problems as a group:

(1) Sufficient heat is added to a 17 gram block of Silver to raise its temperature by 34°C. By how much does the temperature of each gram of Silver within the block increase?

(2) The statement below makes no sense. Explain why.

"The Heat Capacity of Aluminum is 0.21 cal/°C ".

(3) Suppose that a 50 gram block of Aluminum at a temperature of 120°C is brought into thermal contact with a 150 gram block of Aluminum at a temperature of 20°C.

(a) Suppose that 150 calories flows from the hot block into the cold block. Determine how many calories flowed out of each gram of the hot block.

(b) Taking the Specific Heat of Aluminum to be 0.2 calories per gram per degree Celsius, determine the temperature drop in each gram of the hot block.

(d) Determine the temperature rise in each gram of the cold block.

(e) After this 150 calories has been transferred, determine the new temperatures of the hot and cold blocks.

(f) Continue passing calories over in 150 calorie chunks until the blocks reach the same temperature. This is called the equilibrium temperature. What is it?

(g) How many total calories were passed from the hot block to the cold block?