Find an expression for the change in entropy and evaluate the change for following case?

Question

Find an expression for the change in entropy when two blocks of the same substance and of equal mass, one at temperature Th and the other at Tc are brought into thermal contact and allowed to reach equilibrium. Evaluate the change for two blocks of copper, each of mass 500 g with heat capacity of 24.4 JK^-1, taking Th=500K and Tc=250K. Thank you very much for responds

Answer 1

First, Do you know calculus?
Second, a correction to the given heat capacity of 24.4 J/K, which looked like for the block of 500g Cu, is actually for 1 mole or 63.546 grams of Cu.
Hence the heat capacity for one block is:
C = (500g)*(24.4 J/K·mol)/(63.546 g/mol) = 192 J/K.
The final temperature of both blocks is 375K.
Thus the change in entropy is (here I use simple calculus):
[Integral](250K to 375K) CdT/T - [Integral](375K to 500K) CdT/T
= C ln (375/250) - C ln (500/375)
= C ln(375^2/(250*500))
= C * 0.118
= 22.6 J/K