A pure solid such as naphthalene is heated until it all melts and the temperature of the liquid is then 90 degreesC. When the liquid cools, its temperature falls to about 800 C and then it remains constant for several minutes before failing again.
I. Draw a rough sketch of the cooling curve, using axes marked temperature and time.
II. What does the temperature of 80 degreesC represent?
III. Why does the temperature remain constant at 80 degreesC even though heat is lost to the surroundings?
IV. Why does the temperature fall again later on?