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Easy heat capacity problem please solve

  1. Mar 13, 2015 #1
    • HW Template missing as it was moved from another forum
    I recently encountered this problem in class
    "A glass pot of mass 0.6kg contains 1.2kg of oil at 15 degrees Celsius. If 214kJ of energy is supplied to it, what is the final temperature of the pot and oil? ( The specific heat capacity of glass is 700 J kg-1 °C-1, and the specific heat capacity of oil is 2200 J kg-1 °C-1 )"
    Please help!
    Any help would be greatly appreciated!
     
  2. jcsd
  3. Mar 13, 2015 #2

    Suraj M

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    Give it a try yourself, first.
    Do you know any equations which involve change in temperature and heat required to do so?
    If you do, equate the heat supplied to the sum of that equations for both the oil and container, remember final temperature for both the constituents must be equal
     
  4. Mar 13, 2015 #3
    I don't know but I guess I have to apply the formula
    c=E/ΔT
    where c is the heat capacity, E is Joules, and ΔT is the temperature difference

    I know that if there is 214kJ of energy supplied to the pot, the final temperature of the pot would be

    Let x degree Celsius be the temperature difference

    700=214000/x
    ∴x=305 degree Celsius.

    Final temperature
    Initial temperature + x
    =15+305
    =320 °C

    However, I don't know how to relate the pot to the oil and find out the final temperature of two objects with different heat capacities.
    Thanks.
     
  5. Mar 13, 2015 #4

    Suraj M

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    I don't see mass there? It should be in there.
    the heat=214000 should be equated to sum of the heat absorbed by the oil and container.
    This is just your ##E_1## find ##E_2## which is for the oil then add and equate to heat supplied.
     
  6. Mar 13, 2015 #5

    SteamKing

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    Given the units of specific heat capacity (J / kg / °C), don't you think it's reasonable to assume that the mass of a substance figures in to how much energy it takes to change its temperature?
     
  7. Mar 13, 2015 #6
    So what you are saying is that the pot and the oil don't both absorb 214kJ of energy, instead they divide 214kJ up and both take up portions of that energy?
     
  8. Mar 13, 2015 #7

    Suraj M

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    Precisely, equate it, you'll get an equation with 1 variable, solve.
     
  9. Mar 13, 2015 #8
    And also, is the mass of an object is directly proportional to the energy it takes up?
    I am assuming the pot is 0.6 kg and the oil is 1.2 kg,
    therefore divide 214 kJ by 18 pieces and times 6 for the energy taken up for the pot, and times 12 for the energy taken up for the oil.
    I don't know whether if it is really that straight-forward, but I am assuming it is.
     
  10. Mar 13, 2015 #9

    Suraj M

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    No, it's not, you also have to consider their specific heats.
    Don't complicate it,Leo.. you have your equation##E=mcΔT##from this find ##E_1~and~ E_2## add and equate to 214000, don't worry about how the energy is divided, you don't need to.
    Try to form the equation, i described above.
     
  11. Mar 13, 2015 #10
    Oh I see... Thanks a lot for the help!
     
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