(A Cool Lab)

Discussion:
You know that it takes 1 calorie of energy to raise one gram of water 1ºC.  Is it going to take more or less calories to melt ice?
Question A: How many calories of heat, do you think, are needed  to melt one gram of ice?

Materials: 1 large styrofoam cup, thermometer, hot water, ice

Procedure :
1) Find the mass of styrofoam cup. Record as M_cup.
2) Fill the cup about half  full of water having a temperature of about 35ºC.
3) Find the mass of the cup and water to determine the mass of the water. Record as M_water.
4) Stir the water to make sure the water is uniform throughout, and then measure the temperatureto the nearest 0.1ºC. (In other words, get it as accurate as you can). Record as T_s
5) Take two ice cubes or a chunk of ice about the size of two ice cubes and dry the ice  with a towel.
6) Place the ice in the cup carefully. If you splash any water out, start over.
7) Stir the ice and water until all the ice has melted. Again read the temperature as accurate as possible to get the finaltemperature. Record as T_f.
8) Determine the mass of the ice that melted. Record as M_ice.
9) REPEAT STEPS 1-8 2 MORE TIMES FOR A TOTAL OF 3 TRIALS.

Calculations :
Use the equations below to calculate L_fusion ( which is the number of calories needed to melt one gram of water) for all three trials. Show ONE 5-STEP CALCULATION. (C_cup = 0.21 cal/gºC, C_water =1.0cal/gºC )
        HEAT_{lost by cup} + HEAT_{lost by water}= HEAT_{melt ice}+ HEAT_{warm ice's water after melted}

or in terms of the  variables recorded...
 
Mcup ^. Ccup ^. (T_s- T_f) + M_water^. C_water(T_s- T_f) = M_ice ^. L_fusion+ M_ice ^. C_water^. (T_f-0º)

Question 2: How does the heat needed to melt one gram of solid water compare with the heat needed to raise the temperature of 1 gram of liquid water 1º C?

Question 3: When liquid water freezes (changes from liquid to solid), how much heat is released to the environment per gram of liquid water?

Question 4: Since heat to melt does not result in a temperature change (both liquid water and solid water are at 0º), where does the energy go?

Question 5: Some orchards run smudge pots burning oil in freezing weather to heat the air in an attempt to keep the buds from freezing. Others spray water into the air which then freezes on the trees - why would they want to do this?

Question 6: How would you guess that the heat of fusion of water compares to the heats of fusion of other substances?