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Another specific heat question

  1. Nov 5, 2011 #1
    1. The problem statement, all variables and given/known data

    A 28.2 g sample of nickel is heated to 100 degrees C and placed in a coffee cup calorimeter containing 150g of water at a temperature of 13.5 degrees C. After the metal cools, the final temperature of the metal and water is 25 degrees C. Calculate the specific heat capacity of nickel.


    2. Relevant equations

    Q=mcdeltaT

    3. The attempt at a solution

    first calculate Q for water.
    Q=mcT
    =(150g)

    But what is c for water at 13.5degrees??? Problem, now I don't know what to do from here.
     
  2. jcsd
  3. Nov 5, 2011 #2
    c = the specific heat capacity which is a constant or a material ie. the specific heat capacity for water is 4.18 JK^-1g^-1


    ;)
     
  4. Nov 5, 2011 #3
    Um, water has different c values at different temperatures.

    http://en.wikipedia.org/wiki/Heat_capacity#Table_of_specific_heat_capacities

    Water at 100 °C (steam) gas 2.080 37.47 28.03
    Water at 25 °C liquid 4.1813 75.327 74.53 4.1796
    Water at 100 °C liquid 4.1813 75.327 74.53 4.2160
    Water at −10 °C (ice)[20] solid 2.11 38.09 1.938
     
  5. Nov 5, 2011 #4
    not according to my text book. I think that specific heat capacitys must change when they states are change. If that is that case, at 13 degrees, water should still be 4.1813. (I'm only making assumptions here)
     
  6. Nov 6, 2011 #5

    Borek

    User Avatar

    Staff: Mentor

    As explained in other thread - specific heat is a function of temperature, but differences are usually small enough that we can assume it is constant - as long as the substance doesn't change its state. This is especially true for water and most metals between 0-100°C. Use 4.18 J/Kg and don't worry.
     
  7. Nov 6, 2011 #6
    Sorry. Will fix later.
     
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