a sample consisting of 1-bromopropane and 1-chloropropane isinjected into a gas chromatograph quipped with a nonpolar column.which compound has the shorter retention time? Explaine the answer.
b.if the same sample were run several days later with theconditions as nearly the same as possible, would you expect theretention times to be identical to those obtained the first time?Explain.
3 answers
a. I would expect the lower molar mass compound to be held up the least.
The more nonpolar compound will have the higher retention time
1a) Because we are using a nonpolar column, the more nonpolar compound will have the higher retention time. Both these structures are remarkably similar, but because chlorine is more electronegative, this makes it more polar. Thus, 1-bromal will be more nonpolar, and will have the higher retention time, making 1-chloro have the shorter retention time.
1b) If none of the conditions are changed, then the retention time will not change either. So in this case, since the conditions are identical, we will expect identical retention time from the first time and several days later.
1b) If none of the conditions are changed, then the retention time will not change either. So in this case, since the conditions are identical, we will expect identical retention time from the first time and several days later.