A sample of hexane and octane is injected into a gas chromatograph equipped with a nonpolar column. Predict which one will have the shorter retention time.
So, i was thinking that hexane is less polar so it will come out faster, meaning that it will have a shorter retention time?
Agreed, it is also the equivalent of a boiling point separation.
Thanks sooo much!!!
In gas chromatography, the retention time refers to the time it takes for a compound to travel through the column. The retention time depends on several factors, including the boiling point, volatility, and polarity of the compounds being analyzed.
In this case, hexane is a smaller hydrocarbon with a lower molecular weight and a lower boiling point compared to octane. Hexane is a straight-chain alkane with six carbon atoms, while octane is an alkane with eight carbon atoms. Due to its smaller size and lower boiling point, hexane is more volatile and has a tendency to evaporate more easily.
The nonpolar column used in the gas chromatograph is designed to separate compounds based on their polarity. Nonpolar columns generally have a higher affinity for nonpolar compounds and shorter retention times for these compounds.
Given that hexane is less polar and more volatile than octane, it is expected to have a shorter retention time in the nonpolar column. Hexane will travel more quickly through the column compared to octane, resulting in a shorter retention time.
To summarize, based on their molecular properties and the use of a nonpolar column, hexane is predicted to have a shorter retention time compared to octane in the gas chromatograph.