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Are hydrocarbons miscible?

  1. Jun 17, 2008 #1
    I don't know if I used the right word, it's been awhile since chemistry. If I melted parrafin wax and petroleum jelly would they mix like water and salt? Or would they remain seperated?

    Also, lets say I had a sample of a mixture of various unknown petroleum based solids and high viscosity fluids. How would I determine the make up of that sample?
     
  2. jcsd
  3. Jun 19, 2008 #2

    chemisttree

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    They would probably be miscible at elevated temperature. As the sample cooled, the parrafin would likely crystallize out somewhat and you would probably have finely-divided wax crystallites embedded within a petroleum jelly (contaminated with some uncrystallized wax) matrix.

    There are many ways. You could determine the crystallinity of the sample by optical methods or by X-ray or even by synchrotron radiation methods. You could separate the sample based on some affinity to a high surface area material like silica gel or alumina which would give you a 'chromatographic' separation. Identification of the relatively pure fractions would be done by other methods like elemental analysis, UV-Vis, NMR or mass spectrometry. There are others as well but you get the idea.
     
  4. Nov 13, 2008 #3
    Have to disagree with you here, having worked on petroleum jellies developments for about 15 years (what a way to spend your life eh?).

    If you mixed together molten paraffin wax and molten petroleum jelly they would mix together completely, in all proportions. This is because petroleum jelly is generally a blend of white liquid paraffin and paraffin wax. By mixing together molten paraffin wax and molten petroleum jelly you are simply adding wax content to the petroleum jelly. So, as the sample cools it will simply form petroleum jelly again, just slightly harder and a little higher in drop melting point.
     
  5. Nov 13, 2008 #4

    chemisttree

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    And just why is petroleum jelly not water clear? Could there be wax crystallites embedded within the matrix? I've done a little work myself on wax/oil suspensions, but not 15 years worth.
     
  6. Nov 13, 2008 #5
    Petroleum jelly is not transparent for the same reason that paraffin wax is not transparent. The wax contains a range of molecular sizes, so the crystal sizes show a fair degree of polydispersity which means that light tends to be scattered by them.

    When molten petroleum jelly cools the wax matrix traps the oil in its interstices to create the gel structure; if you add molten paraffin wax to molten petroleum jelly, this wax simply adds to the density of the matrix that would otherwise be formed, so that the light scattering effect is still present.
     
  7. Feb 14, 2011 #6
    Dear all,
    Could you answer this question.
    Is there any wxes and oils which are mutually immiscible?
    I want to melt a wax in a oil, and then cool-down the system to see wax separate as tiny bubbles in the oil phase (while agitating continuously).
     
  8. Feb 15, 2011 #7
    Hmmm... I'm not sure about tiny, but beeswax in olive oil will do that to some extent. I wouldn't call that mutually immiscible though, but it seems to match your desired end result. If you want a bigger gradient, you could try parrrafin and something like clarified peanut or sesame oil (be CAREFUL).
     
  9. Feb 16, 2011 #8
    Dear all
    The rule "like disolves like"
    you know waxes are not crystals then not recrystalize in the mixture with oil ,like crud oil which composed wax,grease ,oil and variable hydrocarbons.
     
  10. Feb 16, 2011 #9
    Interesting... so if I take Olive oil, and sesame oil and mix them with heat, I won't be able to see seperation during the cooling phase? Hmm.
     
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