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March 26, 2015

March 26, 2015

Posted by **beti** on Thursday, October 17, 2013 at 11:55am.

- chem -
**Jai**, Thursday, October 17, 2013 at 12:46pmRecall that the heat absorbed (+) or released (-) by a substance is given by

Q = mc(T2 - T1)

where

m = mass (g)

c = specific heat capacity (J/g-K)

T2 = final temperature

T1 = initial temperature

Note that in the problem, the source of energy or heat came from the alloy. Thus we say that heat released from the alloy is absorbed by the water and cup, or:

Q,alloy + Q,water + Q,cup = 0, or

-Q,alloy = Q,water + Q,cup

Let c = specific heat capacity of alloy

Note that the final temperature is the same for all. For the cup, the given is heat capacity, not specific heat capacity (which is per mass). And the initial temperature of water & cup are the same, since they're in equilibrium before the alloy is added.

Substituting,

-(30.5)*c*(31.1 - 90.7) = (48.8)*(4.184)*(31.1-22.3) + (9.2)*(31.1-22.3)

1817.8*c = 1877.7

c = 1.03 J/g-K

Hope this helps :)

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