Qualitative analysis - in the identification of the acetate radical, as we may have some probs in recognizing?

Question

the smell of vinegar ( i have a stuffy nose), so our chem sir told us to add 'SOMETHING' with the given unknown salt in a watchglass,and make a thick paste, and things will be 'SOMEHOW' easier for us.
do u have any idea about these 'something' and 'somehow' ??? plz help me , i've got my exam tomorow.....
i guarantee to select the most convincing answer as the best one.
thanks for ur help.

Answer 1

The classical smell test for acetate ion is to form the pentyl ester. This is best done by first acidifying with something like sulfuric acid. Once you have acidified the solution, test with pH paper to be sure. Then add n-pentanol or "amyl alcohol" and heat the mixture in the test tube. It should form the pently ester which has a very strong banana smell.

Answer 2

Fun question.

My suggestion is a drop or two of 6M HCl.

My reasoning is that you have an “unknown salt”. The cation attached to that salt could be very large and dense. Thus it could be limiting the ability for those little acetate ions to get air borne.

Now why not create the lightest molecule possible out of those acetate ions? - Acetic acid. That concentration of HCl should not have too much of a smell, but you should test the blank HCl first to make certain it is odorless. Yet the strong acid will protonate most if not all of your acetate. This approach would maximize your vinegar smell.

Practice good vapor sampling technique wafting the vapors to your nose and keeping the vessel away from your nose. Vapor lock and chemical burns to the nose and lungs are a very real risk when you’re working with strong acids. I know this from first hand experience.

Why not one of the other strong acids like H2SO4, or HNO3? Well its because of their oxidizing power. That sulfuric can react with the salt to create sulfides, which at best will stink, and possibly be toxic if you inhale enough. And the nitric could create nitrate esters with also have a smell, and of course another fun property which you can research on your own.