[kellychan]

error and precaustion for this experiment??

[xiankai]

error for what? rate of reaction? optimal product yield? what are you trying to measure in the experiment?

[kellychan]

Esterification is the formation of ester from alkanol and alkanoic acid.
CH3COOH + CH3CH2OH ? CH3COOCH2CH3 + H2O
 In my experiment, acetate ions are assumed to be present. Firstly, concentrated sulphuric acid is added to turn acetate ions into alkanoic acid.
CH3COO- + H+(aq) ? CH3COOH
Then ethanol is added. The fruity smell of ester then confirms the presence of acetate ions.  


My question is whether  there is any major errors and precautions in this esterification experiment.

[Yggdrasil]

One precaution would be for the concentrated sulfuric acid, which is caustic and dangerous.  The reaction should probably be done in a solution of phosphoric acid with a catalytic amount of sulfuric acid.  The acid isn't there to protonate the acetate ions, really.  The acid will activate the carbonyl of the acetic acid by protonating the carbonyl oxygen.  This increases the electrophilicity of the carbonyl carbon, making it more succeptible to nucleophilic attack by the ethanol.  

If you are concerned with yield, take note that the reaction is easily reversible.  Since water is a product of your esterification, the presence of water will decrease yield of your ester.  This is the primary reason why you would want some concentrated sulfuric acid, to quench the water in the reaction mixtrue.  Removing water from the reaction mixture is not necessary, however.  To increase yield, you can also use an excess of one of your reactants (e.g. use 5 mol acetic acid/mol ethanol).

The reaction usually requires heating to make the reaction proceed at a reasonable rate.  In an organic lab, this would mean using an air condenser and performing the reaction at reflux.  If you don't have access to such equipment, be sure to perform the experiment in a well ventillated area.

[jdurg]

Just as a side note, please try and be as specific as possible in your questions.  We can't just give you the answer as that will in no way be to your benefit.  It's purely psychological, but the more time a person spends on posting their question, the more time other people will spend reading their question and helping them out.  Just posting 'Tell me what this is' won't result in any constructive help at all.

Also, please refrain from posting the same question in multiple forums.  Put your question in the appropriate forum and eventually people will get around to it.  If it's posted across multiple forums, all of them will be removed.  Thank you.