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Homework Help: Heat of fusion + Melting Ice

  1. Dec 5, 2006 #1
    1. The problem statement, all variables and given/known data
    How many grams of aluminum at 90 C would have to be dropped into a hole in a block of ice at 0 C to melt 20 g of ice.

    2. Relevant equations
    Q = mcdelta T and Q = mLf
    c(H2O) = 1 cal/g.C
    c(Al) = 0.215 cal/g.C

    3. The attempt at a solution

    I can find the heat of fusion Q = (20 g)(79.7 cal/g) = 1594 cal.
    The next step I thought would be to set that equal to mcdeltaT of the aluminum, but there is no final temp for the aluminum. I don't know if I am supposed to find the final temp first or how I would do that to find the mass of the aluminum.
    Last edited: Dec 5, 2006
  2. jcsd
  3. Dec 5, 2006 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Only a small portion of the block of ice melts. So what must be the final temperature?
  4. Dec 5, 2006 #3
    Do you know anything about equillibrium? It could be easily shown that this system would reach steady state right?
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