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What makes gasoline/alcohol so volatile?

  1. Jan 6, 2010 #1
    I have always been amazed at how well gasoline and highly purified alcohols are at cleaning things. It almost seems as if they are microscopic organisms that eat the filth away. I even remember as a kid, putting gasoline in a styrofoam cup, only to see it dissolve away. What is this mechanism?
  2. jcsd
  3. Jan 6, 2010 #2
    Volatility is a thing, ability to dissolve some substance is another. If you refer to the second, it's a property that all fluid chemicals have, just think about water and a very water soluble substance (there are many). Styrofoam is almost made of air, so it's for this reason it dissolves quickly; if you could make such a porous material with table salt, you would see it dissolved by water with similar speeds (and gasoline would do nothing to it).
  4. Jan 6, 2010 #3
    Most of these substances that have these "magical" cleaning properties, as you said, are alcohols. Alcohols by definition have a hydroxyl functional group somewhere on them. This hydroxyl group unlike the rest of the molecule is highly polar. Take for instance ethanol, it's got the polar OH on one end, but the CH3CH2 is non polar. Because it's got these both, and because similar dissolve each other, it means that alcohols can dissolve a wide range of substances.

    Polarity: just a momentary difference in charge, that causes a charge imbalance within the molecule. Depends on the electronegativities of the associated elements and the structure of the molecule itself.
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