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Homework Help: Phase change question

  1. Feb 24, 2006 #1
    I have a question about droping ice into water and working out the final temp.
    ice is -10 and water is 20 degrees c, I know that from -10 to 0 I can use,

    Q = m.c.delta theta

    but does this give me the final answer or do i need to use, Q = m.l, after 0.

    I think this because this equation is used when no change in temp occurs, also after 0 do i go back to original equation?

    thanks, Dan
  2. jcsd
  3. Feb 24, 2006 #2


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    Not only will the ice be warming up, but the water will also be cooling down; this needs to be factored in also.
  4. Feb 27, 2006 #3
    i realise that from -10 to 0
    the heat lost by the water = the heat gained by the ice

    but what i don't quite get is that after that how do come to a final figure?

    I have been given the latent heat of ice so this makes me think it needs to be involved not just using,

    Q=mc delta T

    meaning (T - 30) and (30 - T)

    As in -10 to 20 celsius.
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