[darkshines11]

Hi,

I've recently started discovered I need to do some practical chemistry as part of my degree but as a physics student I have done zero chemistry since high school and my supervisor doesn't know anything either. I just wondered what Chemists mean by the term 'wash'. I keep reading experiment instructions that say wash with chloroform for example. How would I go about doing this? Would it be using a separatory funnel or am I completely wrong about that? Any help would be much appreciated - I am clueless!


Apologises if this has already been asked, I did a quick topic search but didn't find anything that fully answered my question

[JustinCh3m]

If you had a compound that was impure or "dirty," you could "WASH" it with a solvent.  The solvent of choice would be one that does not dissolve your compound but DOES dissolve any impurities.  Sometimes this can be done in something as simple as a small erlenmeyer flask. 

Grab an organic chem. lab book and you should be able to find an example of washing. 

Additionally, sometimes hot solvent vs. cold solvent could come into to play.

[fledarmus]

In organic synthesis, you will find frequently find "wash" in a sentence like,

"The compound was dissolved in ethyl acetate, washed with water, aqueous sodium bicarbonate, and brine (or saturated sodium chloride), dried over MgSO₄, filtered and stripped."

In that case, yes, you put your solution of compound and ethyl acetate in a sep funnel; add water, shake, remove the water; add sodium bicarbonate solution, shake, and remove the bicarbonate solution; then add brine, shake and remove the brine. The water wash will remove any water soluble impurities; the sodium bicarbonate wash will remove acidic species or ensure that any amines are in their free base form; and the salt wash will remove most of the remaining water dissolved in the ethyl acetate. Final traces of water are removed by the MgSO₄.

[darkshines11]

Thanks very much for your *delete me* Looking at the instructions it's very similar to those quoted above so it looks like I will need a separatory funnel.