Calculate the change in entropy of the universe

[Harmony]

Homework Statement

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?

 

[Mapes]

Carry your units through the calculation and you'll see.

 

[Harmony]

Thanks a lot Mapes! I never realize that it is heat capacity instead of specific heat capcity (as they give us mass in the question). :)