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Homework Help: Change of Phase and Latent Heat

  1. Jan 19, 2005 #1
    I am trying to word this question as best as I can.

    Once water has reached its bottom-notch state/position, will the temperature increase?

    I mean, if water changes to steam once heat is added, why won't the temp. increase (or stay constant)?

    Another question is why won't the temp. rise if heat is added to ice when 0 degrees Celsius is reached?

    Thanks again, and I'm sorry if I worded this confusingly.
  2. jcsd
  3. Jan 19, 2005 #2
    The answer to your question is that ( for ice lets say ) if the temp is below 0 degrees celsius then all of the energy from the heat source is going into raising the temperature ( ie magnifying the vibrations of the water molecules ) however once 0 degrees is reached the molecules obtain enough energy to break free from each other, that is all the energy from the heat source goes in to breaking the IMF between them, so in a sense the temp doesn't increase because all of the energy goes in to breaking the bonds between the molecules. Once all of the molecules have broken free ie: ice into water, the temp will continue to increase.
    Last edited: Jan 19, 2005
  4. Jan 19, 2005 #3
    What about the first scenario with steam?

    Did I word it incorrectly?
  5. Jan 19, 2005 #4
    The same argument goes only now the "before" state and "after" state has changed ( ie water to steam ) as well as the critical temp. Once the temp at which water boils (100 deg Cel. ) is reached, All the energy provided by the source of heat goes in to changing the state of the substance, ie: breaking the bonds completely between the water molecules thus forming a gas. Thus this argument can be applied to ANY state change of the substance,,,, the temp rises, then at the critcal point whether its the MP, BP, FP, or whatever the energy goes into the formation/breakage of bonds.
    Last edited: Jan 19, 2005
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