H-2a  Latent heat of fusion

OBJECTIVE: To measure the latent heat of fusion, L_f, of ice.

APPARATUS:

  Chrome plated brass calorimeter (cup), brass stirrer, water jacket for thermal ballast, digital thermocouple type thermometer, ice bucket; ice (opposite 4411 Sterling), double pan balance; 400 ml glass beaker; coffee pot for hot water, selection of slotted masses.

SUGGESTIONS:

 

1)

Find the mass of the calorimeter plus stirrer.

2)

Add $\sim$300 g of water at temperature T as far above jacket T as one expects the final T will be below it, (thus minimizing heat exchange with the environment). For this estimate assume that one will add 60 g of ice. Record the mass of the water.

3)

Record the water temperature in the calorimeter each minute for several minutes while gently stirring.

4)

Gently add (without splashing!) the $\sim$60 g of ice in one or a few pieces after carefully drying each piece with a paper towel. Continue recording the temperature each minute until five minutes after it begins a slow rise.

5)

Record the final mass of calorimeter plus contents. Deduce the mass of ice added.

6)

Plot the temperature vs time as recorded in 3) and 4).

7)

From the data calculate L_f of ice. (You may neglect the heat supplied by the thermocouple type digital thermometer.)

8)

Estimate quantitatively the error in L_f. [Recall that actual (not relative) errors add when you add or subtract, whereas relative errors add when you multiply or divide.

SPECIFIC HEAT CAPACITIES
(in kcal/kg/K or cal/g/K)

  water------ l.00  glass------  0.199
  brass------ 0.090 		 Hg-------- 0.033

OPTIONAL:

  Use the method of H-4 to correct for net heat flow between calorimeter and jacket. Does the correction appreciably alter your L_f?