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Enthalpic Excess Function - Phase Separation in Regular solutions

  1. May 22, 2014 #1
    My professor, in his handout (picture below), says the following about this diagram :

    I disagree with him partly. For [itex]\Delta_{mix} G/nRT<0[/itex] mixing is spontaneous and hence there solutions would be miscible. Hence at [itex]\beta=2.5[/itex] should we not expect the components to be fully miscible. ?

    Following on from this logic; for [itex]\beta=3[/itex] the components are only miscible for [itex]\Delta_{mix} G/nRT<0[/itex] so the maxima represents a phase separation between the two components.

    Who is correct ?

    Additionally,the webpage below indicates that at the maxima there is one phase whilst at the minima there are two. Does this mean at the maxima the solutions are miscible ? If so, how can this be true given that [itex]\Delta_{mix} G/nRT<0[/itex] is positive and hence mixing is unfavourable ?

    http://www.chm.bris.ac.uk/~chdms/Teaching/Chemical_Interactions/page_17.htm [Broken]

    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. May 22, 2014 #2
    Any ideas ?
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