Question

A chunk of ice of mass m1 = 100 g at a temperature t1 = 0 °C was placed in a calorimeter in which water of mass m2= 100 g was at a temperature t2. Assuming the heat capacity of the calorimeter to be negligible, find the entropy increment of the system by the moment the thermal equilibrium is reached. Consider two cases:

(a) t2 = 60°C;

(b) t2 = 94°C.

Answer 1

(a) Here t2 = 60°C. Suppose the final temperature is t°C. Then heat lost by water = m2 c (t2 -1)

heat gained by ice = m1 qm + m1 c (t - t1 ), if all ice melts In this case m1 qm = m2 x 4.18 (60 - t) for m1 = m2

So the final temperature will be 0°C and only some ice will melt.

(b) If m2ct2>m1qm then all ice will melt as one can check and the final temperature can be obtained like this