[mrjdfield]

Hi All,

With my IB class today I was running a standard lab I have done many times on the oxidation of alcohols, using potassium dichromate solution to see the oxidation (or otherwise) of primary, secondary and tertiary alcohols, but it just wasn't working right. I eventually traced the problem to my lab technicians not having acidified the dichromate. However, the process of solving this problem raised a question of its own:

When I add 2-3 ml of ethanol to 2-3 ml of non-acidified potassium dichromate solution, I see a heavy pale-orange precipitate. What is this?

My thoughts are either that it is just potassium dichromate that has precipitated out due to a change in solvent environment (but the orange is too pale for for this), or it is some kind of coordination complex (but really not sure what).

Your thoughts on this would be much appreciated.

Cheers,

Jon

[Borek]

Can't think of better explanations than the two you already suggested.

(I know it doesn't help much  )

[kriggy]

I think it would be dichromate, its insoluble in alchohols.

[mrjdfield]

Thanks both, if I have time I'll have a little play with it and get back to you.