HEAT OF CHANGE OF STATE 33 



e. 1805 : 339-341. Heat of Vaporization. 



/. 1806 : 350. Heat of Fusion. 



g. 1807 : 189-190. Heat of Fusion. 



h. 1807 : 204-205. Heat of Vaporization. 



i. 1808 : 239-240. Latent Heat of Fusion and of Vaporization. 



j. 1809 : 184-185. Heat of Fusion. 



k. 1809 : 194. Heat of Vaporization. 



Experiment 14. Heat of Vaporization and of Fusion. 



Apparatus : Burner, ring stand, asbestos mat, 3" evaporat- 

 ing dish, thermometer. 



Materials : Ice. 



a. Put about 5 c.c., of ice water in the evaporating dish 

 and see how many minutes it takes to bring it just to a boil. 

 Then, keeping the burner in the same position and condition, 

 see how many minutes it takes to boil away the water. How 

 many calories did it take to raise the temperature of 5 c.c. 

 ( = 5 grams) of water from Centigrade to 100 Centigrade ? 

 Since the amount of heat which is received from a burner is 

 nearly constant, about how many calories did it take to boil 

 away the liquid ; that is, how much did it take to change 5 c.c. 

 of water at 100 C. into steam at 100 C.? Then how much 

 did it take for one gram of water ? 



6. Put 5 g. of ice in the evaporating dish, place it on the 

 mat, over the burner, and see how many minutes elapse before 

 it is melted. Then continue to heat the -water for the same 

 number of minutes. At the end of this time note the tem- 

 perature of the water. How many calories of heat were re- 

 quired to change 5 g. of water from C. to the final tempera- 

 ture ? Then how many calories for 1 g. of water ? Since the 

 heat which was received from the burner may be considered as 

 being constant, how many calories were needed to melt 1 g. of 

 ice ? Compare your results with any of the reference books, 



