120 g insulated aluminum cup at 13°C is filled with 140 g of water at 58°C. After a few minutes, equilibrium is reached.(adsbygoogle = window.adsbygoogle || []).push({});

I found the final temperature to be 51°C.

But I am having trouble finding the total change in entropy.

I was using

13°C = 286.15°K

51°C = 324.15°K

58°C = 331.15°K

ΔS = ΔS_cup + ΔS_water

= Q_cup/T_avg + Q_water/T_avg

= (MCΔT)_cup/T_avg + (MCΔT)_water/T_avg

= (120g * 0.22 * (324.15°K - 286.15°K))/((324.15°K + 286.15°K)/2)

+ (140g * 1 * (324.15°K - 331.15°K))/((324.15°K + 331.15°K)/2)

=0.296567

But I am told this is the wrong answer. What am I doing wrong here?

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# Homework Help: Total change in entropy, what am I doing wrong?

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