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Homework Help: Thermodynamics: heat needed to melt block of a metal

  1. Jun 18, 2011 #1
    1. The problem statement, all variables and given/known data
    the latent heat of fusion for this metal is 500Cal/kg. The latent heat of vaporization is 600Cal/kg and specific heat of the liquid metal is 500C/kg K. How much heat is needed to melt an 8kg block of this metal when its temperature is exactly at the melting point?


    2. Relevant equations
    T= kelvins
    c=specific heat
    Q is heat needed

    Q= m*c*delta T
    Q=m*Latent heat (either fusion or vapor)
    3. The attempt at a solution

    Q= 8 * 500Cal/kg


    Will someone please sho wme how to do this>?
     
  2. jcsd
  3. Jun 18, 2011 #2

    danago

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    Gold Member

    What makes you think your answer is wrong?
     
  4. Jun 18, 2011 #3
    The answer was 1600..?
     
  5. Jun 18, 2011 #4
    thats the problem. my coices are 400, 100, 200, 1600 and none of the above. and i answered none the above, but answer is 1600.
     
  6. Jun 18, 2011 #5

    gneill

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    Staff: Mentor

    But the answer is clearly NOT 1600. So apparently the marker (or marking program) or the question statement is wrong.
     
  7. Jun 18, 2011 #6

    danago

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    Gold Member

    What units are the answers given in? The only thing i can think of is that the answers are given in some unit besides Calories? Either that, or the answers are wrong.
     
  8. Jun 18, 2011 #7

    mukundpa

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    Homework Helper

    what are the units of energy, cal or cal/kg ?
     
  9. Jun 18, 2011 #8
    ahg i see.
     
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