1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Liquid solutions

  1. Aug 27, 2017 #1
    1. The problem statement, all variables and given/known data
    A solution contains 0.1mol of acetamide in 1Lit of glacial acetic acid.When the solution is cooled,the first crystal that appeared at the freezing point contains the molecules of
    A.acetamide only
    B.Acetic acid only
    C.both acetamide and acetic acid
    D.None
    2. Relevant equations
    Depression in freezing point=(molal depression constant)*(molality of solution)

    3. The attempt at a solution
    I don't see why there should be anything other than C.
    It's a solution..consists of both solute and solvent,which have formed a composite mixture that freezes at the same temperature.So,shouldn't the crystal contain both of those components.
    However,answer given is B
     
  2. jcsd
  3. Aug 27, 2017 #2

    Borek

    User Avatar

    Staff: Mentor

    That would be an eutectic system, not every mixture works this way.
     
  4. Aug 27, 2017 #3
    Oo..well,then how can we predict the answer for this question?
     
  5. Aug 27, 2017 #4

    Borek

    User Avatar

    Staff: Mentor

    Just by looking at the melting points.
     
  6. Aug 28, 2017 #5
    But..that isn't given in the question...and I don't think I'm supposed to remember the melting pt of either acetamide or acetic acid..
     
  7. Aug 28, 2017 #6

    Borek

    User Avatar

    Staff: Mentor

    On the second thought - melting point would be the most important thing for mixture in which molar fractions of both substances involved are comparable. When concentration of the solute is much lower, its activity is also very low, so it can not freeze that easily.

    I don't like the question, I am not convinced the answer is easy to give without additional information.
     
  8. Aug 28, 2017 #7
    Ok,thank you
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Liquid solutions
  1. Pure liquids (Replies: 1)

  2. Liquid CO2 (Replies: 1)

Loading...