Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Boiling point, !

  1. May 11, 2003 #1
    Boiling point, urgent !

    Which of the following has higher boiling point?
    1) Mixture of hexane and propanone
    2) propapone
    (consider their relative molecular mass and the forces of attraction between the molecules)

    I think the mixture of hexane and propanone has a higher boiling point, as propanone has lone pair electrons, therefore the force between the molecules in the mixture is dipole-induced dipole, while the force exists between pure propanone molecules is instantaneous diple-induced dipole.

    However my classmate told me the mixture has a lower boiling point and was confirmed by my teacher.

    I hope I can get your answer in 3 to 4 hours, if not, it's ok and I'll treat this thread as a discussion. Thanks in advance.

    PS. This question is for the theory part of my lab. report. Since the data obtained was ridiculous, that's why I need to know the fact.

    PS2. I need to finish it in 4.5 hours.
  2. jcsd
  3. May 11, 2003 #2
    The boiling point of Propane is -42degrees
    The boiling point of Hexane is 69 degrees

    I think you might be right Mrs Kam
  4. May 11, 2003 #3
    Mrs Kam ??!! I'm not Mrs Kam.

    Propane : C3H8
    propanone : CH3C=OCH3

    In fact, i need to draw a graph, variation of boiling point against % composition by volume haxane/propanone mixture. (This is an experiment on phase equilibrium)
    Last edited: May 11, 2003
  5. May 11, 2003 #4

    hexane: 68.7
    acetone: 56.5

    sounds like a boring lab
  6. May 11, 2003 #5


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    The word "azeotrope" should appear somewhere in the background material for the lab. Prediction of "azeotropes" is a topic for the M&PS forum.
  7. May 12, 2003 #6
    Um..this is wrong. The force between molecules in pure propanone(acetone) is dipole-dipole interaction, since there are 2 lone pair electrons. The bond between molecules in pure hexane is instantaneous dipole-induced dipole. If they are mixed together, hexane molecules will destroy the dipole-dipole interaction between propanone molecules and to form a diple-induced dipole interatction.

    Thanks for your help.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook