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07082011, 03:43 PM #1Medical Student
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 Jun 2011
 Location
 Houston, Texas
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Heat capacity of a coffee cup calorimeter.
How do you solve for the heat capacity of a calorimeter?

07112011, 10:08 AM #2PreDental
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 Mar 2011
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 16

07112011, 10:14 AM #3PreDental
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 Mar 2011
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example question**

07112011, 12:37 PM #4Medical Student
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 Jun 2011
 Location
 Houston, Texas
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 41
................Hot Water.........Cold Water
Volume........100mL ............100mL
Start Temp.....90 C................20 C
End Temp......54 C................54 C
What is the heat capacity of the students coffee cup?Last edited by dsterlingwells; 07112011 at 12:40 PM.

07132011, 02:18 PM #5
 Join Date
 Jun 2007
 Posts
 1,884
For heat capacity look at the unit...should be in J/degree C or cal/degree C (or temperature change in units of Kelvin...same diff). So the heat capacity of a calorimeter is usally calculated by C = q/(delta T).
This is a super tricky question fyi. If you calculate it out (q=mc(delta T)) using the specific heat of water to be 1 cal/(g(degree C))
then the hot water gave off 3600cal [q = (100)(1)(36)]
whereas the cold water absorbed 3400cal [q = (100)(1)(34)].
This leaves 200cal unaccounted for; this must be what the coffee cup itself absorbed (assuming no heat lost to the surroundings). Assuming the coffee cup also started at 20 degrees C and ended up at 54 degrees C:
C = q/(delta T) = 200cal/(34 degrees C) ~ 5.9 cal/(degree C)
Hope this helps!

07132011, 04:11 PM #6Medical Student
 Join Date
 Jun 2011
 Location
 Houston, Texas
 Posts
 41
Yeah i couldn't find a simplified equation for the capacity of the calorimeter. The Kaplan book gives this long explanation but i couldn't understand it. The answer was in J/degree.. so it was 24.6..which goes with your answer.
thanks!