#### Answer

a) -194.5
b) 122
c) -72

#### Work Step by Step

a) Since there are two volumes of equal amounts of the same substance, we know that the final temperature will be the average of the two, which is:
$=\frac{353+283}{2}=318 K $
Thus, we find for the warm water:
$\Delta S = (.25)(4,184)(ln(\frac{318}{383}))=-194.53$
b) For the cold water:
$\Delta S = (.25)(4,184)(ln(\frac{318}{283}))=122$
c) We add these to find the total:
$122-194=-72$