Results are out! Find what you need...fast. Get quick advice or join the chat
x

Unlock these great extras with your FREE membership

  • One-on-one advice about results day and Clearing
  • Free access to our personal statement wizard
  • Customise TSR to suit how you want to use it

Oxidation of Ethanol

Announcements Posted on
Rate your uni — help us build a league table based on real student views 19-08-2015
  1. Offline

    ReputationRep:
    "Describe the complete oxidation of ethanol. Include the conditions, reagents required, and any colour changes."

    OK well I know that you add acidified potassium dichromate (prepared from sulphuric acid) and it oxidises first to ethanal and then to ethanoic acid, or vinegar - which is dark brown?

    BUT I don't know how to put that in a chemical equation, and I don't know the colour of ethanal or ethanol.

    Can anyone help?
  2. Offline

    ReputationRep:
    ethanal and ethanol are both transparent
  3. Offline

    ReputationRep:
    Does acidified potassium dichromate have a colour?
  4. Offline

    ReputationRep:
    (Original post by IBeast)
    Does acidified potassium dichromate have a colour?
    If I remember correctly, acidified potassium dichromate (K2Cr2O7) goes from orange to green during oxidation.

    Is ethanol produced from sulphiric acid always ethan-1-ol, CH3CH2OH? If not, it could of course mean that you get a ketone when oxidised. Also, don't forget that you have to distil immediately first and then reflux...

    So the overall equation for oxidation of ethan-1-ol is:

    C2H5OH + [O] ------> CH3COH + H2O (distill upon heating)

    or if heated with excess K2Cr2O7

    C2H5OH + 2[O] ------> CH3COOH + H2O (heat under reflux)

    Hope this helps!
  5. Offline

    ReputationRep:
    (Original post by Languages Nutter)
    Is ethanol produced from sulphiric acid always ethan-1-ol, CH3CH2OH? If not, it could of course mean that you get a ketone when oxidised. Also, don't forget that you have to distil immediately first and then reflux...
    Ethanol is always a primary alcohol.........
  6. Offline

    ReputationRep:
    D'oh! Sorry - my mistake!
  7. Offline

    ReputationRep:
    Ethanol is always a primary alcohol as it only has 2 carbons. You would heat under reflux with acidified potassium dichromate (vi) (i think its (vi)?). It would go via an aldehyde to ethanoic acid. Yes vinegar is brown but i think you'd write the colour change as being from orange to dark green as thats the colour the oxidisnig agent goes. Ethanol and ethanal are both colourless....

    Hope this helps, I expect cos I'm such a slow typer loadsa people will have already said the same thing!!
  8. Offline

    ReputationRep:
    Thank you very much that's all I need to know
  9. Offline

    ReputationRep:
    For geek points, ask your A level teacher to show you the ammonium dichromate volcano. Get a small heap of said compound, stick an ethanol-soaked splint in it, and light it.

    Might want to do it in a fume hood.
  10. Offline

    ReputationRep:
    (Original post by IBeast)
    OK well I know that you add acidified potassium dichromate (prepared from sulphuric acid) and it oxidises first to ethanal and then to ethanoic acid, or vinegar - which is dark brown?
    H2SO4 is added to potassium dichromate to form the chromate ion and acetic acid is clear and colourless, whatever you do don't say vinegar :tongue:
Updated: April 17, 2009
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

New on TSR

Rate your uni

Help build a new league table

Poll
How do you read?
Study resources
Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.