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oil and water

Discussion in 'Science' started by aldebaran, Mar 15, 2011.

  1. A student posed a question which I will forward on to the collective wisdom of community members: If a state of chaos is more likely than an ordered one, would a beaker of oil and water, if left long enough, become homogenous?
     
  2. phlogiston

    phlogiston Lead commenter

    Maximum entropy is not total chaos - it is a maximisation of the ways of arranging particles (including the surroundings).
    If a change happens, the entropy change of the surroundings is -enthalpy/temperature.
    Now with oil and water, there are quite strong hydrogen bonds between the water molecules, and less strong van der Waals forces between the oil molecules. The intermolecular forces between and oil molecule and a water molecule will be weaker than either of these.
    Consequently mixing the molecules is endothermic, this will absorb energy from the surroundings - and decrease the total entropy of the world /surroundings (as the drop in entropy of the surroundings is bigger than the gain in entropy of the mixture).
    Best wishes,
    P
     
  3. Thanks. That helps!
     

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