Lab chromatography quetion The solvent used in this part of the experiment is ap
ID: 227824 • Letter: L
Question
Lab chromatography quetion
The solvent used in this part of the experiment is approximately 70% hexane and 30% acetone. Hexane is an alkane (a hydrocarbons containing only single bonds) with six carbons. Question 1. What intermolecular forces are present in a pure sample of a linear hydrocarbon such as hexane? Question 2. Keeping in mind your answer to question 1 and the fact that silica is highly polar, which of the bands you measured contains the least polar chromophore? Explain the reasoning behind your answer.
Explanation / Answer
(1) Only London dispersive firce (induced dipole-induced dipole interaction) is present in hexane.
(2) The first band coming out of the column will contain the least polar chromophore. As the polarity of a compound increases it will strongly interact with the polar silica and strongly binds with it. So it will move down very slowly in presence of a non-polar solvent like hexane. Greater the polarity of a component, greater will be its retention time. Non-polar molecules have only weak interaction with polar silica and so moves down the column at a much faster rate.
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