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Homework Help: Heathcapacity problem help

  1. Nov 14, 2005 #1
    Here's my problem

    A box with the heathcapacity 80J/K contains 0,2kg water. The box and the water has together the temperatur 18*C. We put 0,050kg ice with the temperature -15*C in the box of water. Investigate if all ice melts. Don't take with heath from the surrondings.

    Well for this problem I though like this

    0,2Kg Water * 4,19(water's heath capacity) = 0,838 + 80J/K =0,8380008

    Then I took the Ice capacity = 0,050kg * 4,19 = 0,2095

    0,8380008-0,2095 =0,62858

    Then lets do it to Kelvin 273+18=291K
    273-15=258K

    0,62858 * -33 K = -20,7314

    But that doesn't say me nothing if the Ice has melted?

    How do I know that?
     
  2. jcsd
  3. Nov 14, 2005 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Think this way: How much energy is required to melt the ice? You must first raise the temperature from -15 to 0, then melt it.

    Now ask: Does the box + water have enough energy to melt that ice? How much energy will the box + water release if it cooled from 18 degrees to 0?
     
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