[Guitarmaniac86]

Hi,

As part of my practical chemistry module I had to dehydrate cyclohexanol to cyclohexene. This was done using a mixture of phosphoric and sulphuric acid. I took an IR of it and I was told to take a GC of it... The GC showed that the purity was 99.1% for cyclohexene and 0.9% for cyclohexanol and a yield of 56.8%.

I need to know why GC is a good method to test for purity.

I sort of have an inkling of what the answer is so could someone verify it for me?

"GC is an appropriate technique to test for purity because cyclohexene and cyclohexanol are both volatile and therefore easily form in the gas phase. GC is able to seperate the gases, and since both these molecules have different polarities, they will be retained at different rates. This means that one compound will be completely detected with no blurring of the peaks when the next compound is detected. The amount of each can be deduced and a percentage composition can be made up by analysing the peak areas. This therefore can give an indication of purity."

Is this correct or have I gone off on the wrong tangent?

Thank you in advance.

[Arkcon]

That answer is missing nothing, a good job, all around.   'Tho some of the terms are in your own words, and not the technical definitions of the concepts, example, we don't say that "peaks blur" there is a better chromatographic term for peaks that are too close together. 

Also, "easily form in the gas phase" seems a little too colloquial, and not very technical, but you might be better off leaving it, because it's in your own words, and not copied from a book.  Watch stuff like that.  If the instructor calls you on it, it means they expect you to pick up chemistry jargon a little bit more.

[Guitarmaniac86]

Thank you Arkcon