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Homework Help: Determine the final temperature of the mixture homework

  1. Feb 14, 2005 #1


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    A combination of 0.250 kg of water at 20*C, 0.400 kg of aluminum at 26.0*C, and 0.100 kg of copper at 100*C is mixed in an insulated container and allowed to come to thermal equilibrium. Ignore any energy transfer to or from the container and determine the final temperature of the mixture.

    I know to use Q=mc(delta)T and that the energy lost should equal the energy gained, but how do I set up the equation for problems like this?
    One of the things that I don't know how to figure out is whether the aluminum will be losing energy to the water or gaining it from the copper. So I don't know how to set this up.

  2. jcsd
  3. Feb 14, 2005 #2


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    HINT:The total heat transfered must be zero (the absorbed one is positive and the given one is negative,when u add them,they will yield zero).

  4. Feb 14, 2005 #3

    Doc Al

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    Let the equations do the work for you. Each substance (water, copper, aluminum) will have a heat transfer: [itex]\Delta Q_1 = m_1c_1 (T_f - T_i)[/itex]. The total [itex]\Delta Q = \Delta Q_{water} + \Delta Q_{aluminum} + \Delta Q_{copper}[/itex] equals zero and the final temp is the same for all.
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