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Homework Help: Calorimeter heat capacity

  1. Jan 13, 2008 #1
    1. The problem statement, all variables and given/known data
    A copper calorimeter with the heatcapacity of 75 J/K has 300 g of petrolium in it. The starttemp. is 17.8 C. A kobberweight of 100 g. is 100Celcius. It is being put in the petroleum, where the temperature ends up being 22 C. The specifik heatcapacity of coppe ris 387J(kg/K)
    What is petroleums specifik heat capacity?


    2. Relevant equations

    C_pet*m_pet(t2-ts)+C_cop*m_cop(t2-t1)+C_cal*m_cal(t2-t1)=0

    3. The attempt at a solution
    I think I have overlooked something - so I just need hints on the way.

    I don't have the mass of the calorimeter, but I now that it's heatcapacity is 75 J/K and I know that it's made of coper and the specifik heat capacity of that is 387 J(kg*K)

    If that is the way to go, then I have all the variables except the specifik heat capacity of petroleum, and then I just isolate C-Pet and it's piece of cake!
     
  2. jcsd
  3. Jan 13, 2008 #2
    the the mass of the calorimeter must be 75/387 = 0.193 kg = 193 g

    Which then means C_pet*300(22-100)+387*100(22-17.8)+387*193(22-17.8)=0

    C_pet = 20.4 J(kg/K)
     
  4. Jan 13, 2008 #3
    Which isn't true as looking in table it is around 1900 J/(kg*K)
     
  5. Jan 14, 2008 #4
    No help?
     
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