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Does making ice take energy?

  1. Jan 17, 2010 #1
    Hi guys,

    Very long time, no see!

    Quick question: if water is left outside and freezes, was any energy consumed in the freezing process? And if so, would this energy be stored in the ice and be released when it melts?

    My gut is telling me that no energy is needed to freeze water, because the freezing is a result of water molecules moving slower (due to decreased temperature, or decreased energy input.) Perhaps I'm just having a brain-fart in needing to even ask this question.

    Thank you for any input.

  2. jcsd
  3. Jan 17, 2010 #2


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    Staff: Mentor

    Correct: Energy is removed from the water to make it freeze.
  4. Jan 18, 2010 #3


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    Science Advisor
    Gold Member

    If you want to create the conditions, locally, such that you can make ice , however. You need to have already expended energy (running the freezer) in order to shift energy from inside the freezer into the outside world.
    To decrease the entropy ('extracting' some of the thermal energy from your freezer and re-ordering the situation locally), you have had to increase the total entropy of the Universe by burning coal somewhere, to generate the Electricity.
  5. Jan 26, 2010 #4
    hey Im not very much friendly with these thermodynamics.. but I have studied it in my 1st year.. (but now Im in electronic department..!).. anyway I remember the 'entropy' was something which make lot of us crazy and crazy :-)...
    whatever it is I have a comment on this ... yes of course ,you take some coal energy and then you use that energy to extract energy from the water.. no doubt the energy inside the water will decrease and it will be frozen.. my problem is how this entropy comes to here..? everything is fine.. 'but' the disorder of the molecules... ! entropy....!and as I remember the entropy of the universe is increasing but not decreasing..and if Im correct entropy is a line integral.. sometimes I feel that there is a huge relationship between BH loop in the electromagnetic theories and these entropy case...also in BH loop it says that you need some additional influence to bring back the molecules to its initial order from the final order... ahhh... that is why there is a BH loop other than the same reversing path... it is 'maybe' something like a closed cycle of thermodynamics...! Entropy... ! that is amazing... anyway this is just a comment...
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