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Homework Help: What is the final temperature if only one ice cube is used?

  1. Nov 16, 2006 #1
    Two 60 g ice cubes are dropped into 270 g of water in a thermally insulated container. If the water is initially at 25°C, and the ice comes directly from a freezer at -15°C

    What is the final temperature if only one ice cube is used?

    I have no idea where to begin...my teacher didn't give us the formulas that we would need. Any help would be appreciated.
  2. jcsd
  3. Nov 16, 2006 #2
    can i get some help?
  4. Nov 16, 2006 #3
    Calculate the amount of energy you need to completely melt the ice, which will be the mass of ice times the heat of fusion. This is how much energy goes from the water to the ice. This energy loss corresponds to a drop in temperature. You will get a new temperature for the amount of water and your ice will now be water at 0 degrees (Centigrade). Computing the final temperature is a matter of taking a weighted average of the water temperatures.

    You will need the heat of fusion for ice (J/g) and the specific energy (J/g*C) for water, which are constants that can easily be looked up.
  5. Nov 16, 2006 #4
    i am sorry, i'm not following what your saying.
    are you saying.. 334(60)=20040..for the first part?
  6. Nov 16, 2006 #5
    Sorry, I forgot to mention that the ice needs to be heated to 0 degrees Centigrade before it is melted. You will need to find the specific heat of ice as well. And yes, you have calculated the energy required to melt the ice correctly, add to that the energy needed to reach 0 degrees and subtract that from the energy of the water at 25 degree Centigrade..
    Last edited: Nov 16, 2006
  7. Nov 16, 2006 #6
    so.i got .....20040+450-6750=13740
  8. Nov 16, 2006 #7
    is that correct?
  9. Nov 16, 2006 #8
    never mind..i got the answer..thank you
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