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Evaporating salt solution

  1. Jul 11, 2012 #1
    I was messing around with a saturated solution of table salt, when I forgot about it and left it in a fume hood over night. When I came in the next morning the solution had evaporated away, but what surprised me was that there were salt deposits left on the beaker above the initial height of the solution. In fact this is where most of the salt ended up, including some creeping over the top of the beaker. How do I understand this observation?

    My expectation was that the water would evaporate molecule by molecule, leaving the salt in the bottom of the beaker. However if the solution evaporated drop by drop, then some drops might hit the side of the beaker on their way out where it could condense leaving salt behind - but this doesn't make sense with the way I understand evaporation.

    Any ideas?
  2. jcsd
  3. Jul 12, 2012 #2


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    Staff: Mentor

    Nothing unusual. Solution becomes saturated first on the surface. First crystals form out of the saturated solution in the place where it is in contact with a solid. Then these crystals wick the solution up.
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