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Boiling point and evapoaration

  1. Jan 6, 2005 #1
    i know that pure liquids boil at a termperature of 100 degress but what is the difference between evaporation and boiling :grumpy:
     
  2. jcsd
  3. Jan 6, 2005 #2

    dextercioby

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    1.ONLY pure water boils at 100°.
    2.The same process (vaporization,a phase transition from the liquid state to the gaseous state) occurs in two ways under different conditions of temperature and pressure.
    Evaporation takes place at any temperature and any pressure,while boiling takes place at a fixed temperature and a fixed pressure,in the case of water,100° and 1 atm.If you change the pressure,also the temeprature of the boiling point will drop or increase.
    The difference is that evaporation can take place in any conditions,while boiling has tohave certain favorable factors to concur:the presence of so-called "boiling-centers" in the mass of the liquid arounf which the liquid molecules begin to distort their semiordered structure (forund in liquid),to increase the mean distance between them and to go into gaseous state.
    Evaporation assumes that the phase transition can happen on any conditions,not as restrictive as in the case of boiling.Evaporation involves only the outer (superficial) layers of molecules of liquid,while boiling takes place in all the liquid,all molecules are 'changing' relative position.Oceans evaporate,they do not boil.
    Certain knowledge of liquid internal structure might help you more.

    Daniel.
     
  4. Jan 6, 2005 #3
    thanks mate
     
  5. Jan 6, 2005 #4
    erm is there any relation to the paticulate theory?
     
  6. Jan 6, 2005 #5

    dextercioby

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    Never heard of 'particulate theory'.Never heard of the English word 'particulate'.
    Could you rephrase it,please??

    Daniel.
     
  7. Jan 6, 2005 #6
    par·tic·u·late (pr-tky-lt, -lt, pär-)
    adj.

    Of or occurring in the form of fine particles.
    n.
    A particulate substance.
     
  8. Jan 6, 2005 #7

    dextercioby

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    Kay,got it,i was too lazy to look it up in a dictionary,thank you for doing that for me. :smile:
    Yes,there are various theories.The most rigurous would assume a 'particulate' theory of both liquids and gases.Statistical theory.Thermodynamics would assume macroscopic description.Basically a continuous matter description.

    Daniel.
     
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