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Problem in Chemistry

  1. Jan 9, 2005 #1
    A 28.2 g sample of nickel is heated to 99.8 C and placed in a coffee cup calorimeter containing 150.0 g water at 23.5 C. As the metal cools, the final temperature of metal and water is 25 C. Calculate the specific heat capacity of nickel, assuming that no heat escapes to the surroundings or is transferred to the calorimeter.

    I know that

    energy relased = s * m * ∆T

    So would ∆T = 25 - 23.5?

    Also would the mass = 28.2 g

    Finally how would you calculate the specific heat capacity of only nickel?

    Thanks a lot
     
  2. jcsd
  3. Jan 9, 2005 #2

    Pyrrhus

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    There will be a thermo equilibrium so

    [tex] -Q_{nickel} = Q_{water} [/tex]

    [tex] -m_{nickel}c_{nickel} (T_{final} - T_{nickel}) = m_{water}c_{water}(T_{final} - T_{water}) [/tex]
     
  4. Jan 9, 2005 #3
    oh ok

    so the specific heat of water = specific heat of nickel?
     
  5. Jan 9, 2005 #4

    Pyrrhus

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    No, you need to work out the equation to get it.
     
  6. Jan 9, 2005 #5
    wait what is c? aren't you supposed to use s * m * ∆T??
     
  7. Jan 9, 2005 #6

    Pyrrhus

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    C is specific heat. I apologize for my notation, that's how i remember it from the course.
     
  8. Jan 9, 2005 #7
    no problem. was just wondering how you received the thermal equilibrium? Like putting a - sign in front of Q(nickel)
     
  9. Jan 9, 2005 #8

    Pyrrhus

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    As i remember the - sign in thermodynamics means losing heat, and the + sign remember gaining heat, so as you can see there will be an exchange of heat energy between the nickel and the water, til they hit an equilibrium.

    A more "savvy" way, i remember using was looking at the final temperature and at the initial temperature, as you can see the final temperature < initial temperature therefore the incrementum will be negative for the nickel.
     
  10. Jan 9, 2005 #9
    hmmm got 0.93 when answer is 0.45. For ∆T of nickel and water, do you use the same final temperature 25.0 C?
     
    Last edited: Jan 9, 2005
  11. Jan 9, 2005 #10

    Pyrrhus

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    I got 0.445 j/g C, yes you do that's the whole point of thermo equilibrium.
     
  12. Jan 9, 2005 #11
    yes i got that. thanks a lot for helping me
     
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