What is the order that these four compounds would travel through a silica gel column during liquid chromatography?
a) ethylene glycol, HOCH2CH2OH
b) aqueous sodium chloride solution, NaCl (aq)
c) propanol, CH3CH2CH2OH
d) benzene, C6H6
(eluted first), ???, ???, ???, ??? (eluted last)
I was thinking: d, c, a, b
it would be based on size.
In liquid chromatography on a silica gel column, the order of elution depends on the polarity of the compounds. The more polar the compound, the slower it will travel through the column.
Based on the given compounds:
d) benzene, C6H6 (nonpolar compound) will likely elute first since it is the least polar.
c) propanol, CH3CH2CH2OH (moderate polarity compound) will elute second, as it is more polar than benzene.
a) ethylene glycol, HOCH2CH2OH (higher polarity compound) will elute third, as it is more polar than propanol.
b) aqueous sodium chloride solution, NaCl (aq) (highly polar compound) will likely elute last since it is the most polar.
Therefore, the order of elution would be: d, c, a, b
To determine the order in which these compounds would travel through a silica gel column during liquid chromatography, several factors need to be considered. The most relevant factors are the polarity of the compounds and their affinity for the stationary phase (silica gel).
In general, polar compounds have a stronger interaction with the stationary phase and, therefore, elute later. Nonpolar compounds tend to have weaker interactions with the stationary phase and elute earlier. Based on this, we can now analyze each compound:
a) Ethylene glycol (HOCH2CH2OH) is a polar compound due to the hydroxyl (OH) group. It will strongly interact with the stationary phase, resulting in a later elution time.
b) Aqueous sodium chloride solution (NaCl (aq)) is a nonpolar compound because it consists of ionic species (Na+ and Cl-). Since it has no significant interaction with the stationary phase, it will elute early.
c) Propanol (CH3CH2CH2OH) is a polar compound due to the hydroxyl (OH) group. It will show a relatively strong interaction with the stationary phase, leading to a later elution time than nonpolar compounds.
d) Benzene (C6H6) is a nonpolar compound with no functional groups that can strongly interact with the stationary phase. It will have the earliest elution time among the given compounds.
Considering these factors, the correct order, starting with the compound that elutes first, would be:
d) Benzene (C6H6) (eluted first)
b) Aqueous sodium chloride solution (NaCl (aq))
c) Propanol (CH3CH2CH2OH)
a) Ethylene glycol (HOCH2CH2OH) (eluted last)