Calculate the change in entropy of the universe as a result of the following process:
A copper block of mass 0.4 kg and heat capacity 150 JK-1 at 1000C is placed in a lake at 100C.
2. The attempt at a solution
change in entropy (copper) = mc ln (T2 / T1)
change in entropy (lake) = mc ( T1 - T2 ) / T2
where T1 = 373 K, T2 = 283 K.
The answer given is 6.3 JK-1. which is differ from the answer I got. May I know if i have done any careless mistake?