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

Ethanol (=alcohol) added to gasoline

  1. May 10, 2008 #1
    1. Incredibly it appears that in the United States gasoline may have ethanol in it as an additive. Up to 5% can be ethanol in the fuel sold there. Does anyone know if this is accurate?

    2. How do I purify ethanol (=alcohol) to 99%?

    3. Where do I buy 99.9% pure ethanol?
  2. jcsd
  3. May 10, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    Gasoline is a mixture of all sorts of hydrocarbons typically around 5-8 C long so a bit of ethanol isn't going to make a lot of difference.

    You can purify ethanol by simple distillation although it's hard to get above 90% because ethanol readily absorbs water from the air.

    You can buy high purity ethanol from the normal lab supply companies, sigma-aldritch etc but it isn't going to be high purity for long once you open the bottle.
  4. May 11, 2008 #3


    User Avatar
    Science Advisor
    Gold Member

    There's nothing particularly shocking about oil companies adding ethanol to the fuel you buy. More curiously, incentive/legislation is made such that bio-ethanol is added to pump fuel in many countries, which is understandably controversial.
  5. May 12, 2008 #4


    User Avatar
    Science Advisor
    Gold Member

    In modern days, Ethanol is being added to gasoline to raise its effective Octane number. It is basically a replacement for MTBE and tetra-ethyl lead. tetra-ethyl lead was originally used for raising a fuel's resistance to spark knock, followed by MTBE which didn't contain lead, but turns out to be carcinogenic. Basically, Ethanol is one of the only additives that can be used with gasoline that is easy to manufacture and does not have heavily toxic or carcinogenic effects like tetra-ethyl lead or MTBE. Still, I think that many toxic properties of gasoline additives such as MTBE are blown far out of proportion.


  6. May 12, 2008 #5
    Your local liquor store has pure grain alcohol which is 98% alcohol.

    On the other note, with the United States requiring 10% ethanol in gasoline, it is setting up the infrastructure to switch to E85 in the distant future.
  7. May 13, 2008 #6


    User Avatar
    Science Advisor
    Homework Helper

    That would be a special liquor store. Alcohol forms an azeotrope at lower concentrations, so stuff above 96% is going to be hard to find. The usual methods for getting higher concentrations are discussed in fuel distillation sites.

  8. May 13, 2008 #7


    User Avatar
    Science Advisor

    Not in Ohio you won't. Kentucky on the other hand....:devil:
  9. May 20, 2008 #8
    Lightest diesel engine known to man

    Sorry, wrong thread, ignore this.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook