Answer to Question #165069 in Physical Chemistry for Rushank Ukey

Question

Two Block of BCC iron 1 mole each are kept in thermal contact with each other and they are packed in an adiabatic enclosure first block wast at 300 k and second was at 900 k to start with what should be entropy produced ?

Answer 1

When two blocks are kept in contact with each other, the final temperature will be given as:
Tf​=2
T1​+T2​​
Now, we have ΔSsys​=∫T
dqrev​​=nCp​∫T
dT​
For the first block of metal the entropy will be given as:
ΔS1​=nCp​∫T1​Tf​​T
dT​=nCp​lnT1​
Tf​​
Similarily, ΔS2​=nCp​lnT2​
Tf​​
Now, total change in entropy
ΔS1​+ΔS2​=nCp​T1​T2​
Tf​2​
But , Tf​=2
T1​+T2​​
∴ Final entropy will be: nCp​ln[4T1​T2​
(T1​+T2​)2