A2 Organic Question
Please help!
A sample contains a mixture of two esters contaminated with an alkane and an alcohol. Suggest how well these four compounds would be separated using an alkane stationary phase. In your answer, include some indication of the length of the retention times. Explain your answer.
The answer is The esters would have similar retention times AND similar structures/molecules OR same functional groups OR similar polarities OR similar solubilities. Alcohol would have a short retention time AND alkane would have a long retention time
I dont understand how to distinguish between which has a long retention time and which has a short
A sample contains a mixture of two esters contaminated with an alkane and an alcohol. Suggest how well these four compounds would be separated using an alkane stationary phase. In your answer, include some indication of the length of the retention times. Explain your answer.
The answer is The esters would have similar retention times AND similar structures/molecules OR same functional groups OR similar polarities OR similar solubilities. Alcohol would have a short retention time AND alkane would have a long retention time
I dont understand how to distinguish between which has a long retention time and which has a short
Reply 1
Original post
by fantasticbunnyPlease help!
A sample contains a mixture of two esters contaminated with an alkane and an alcohol. Suggest how well these four compounds would be separated using an alkane stationary phase. In your answer, include some indication of the length of the retention times. Explain your answer.
The answer is The esters would have similar retention times AND similar structures/molecules OR same functional groups OR similar polarities OR similar solubilities. Alcohol would have a short retention time AND alkane would have a long retention time
I dont understand how to distinguish between which has a long retention time and which has a short
A sample contains a mixture of two esters contaminated with an alkane and an alcohol. Suggest how well these four compounds would be separated using an alkane stationary phase. In your answer, include some indication of the length of the retention times. Explain your answer.
The answer is The esters would have similar retention times AND similar structures/molecules OR same functional groups OR similar polarities OR similar solubilities. Alcohol would have a short retention time AND alkane would have a long retention time
I dont understand how to distinguish between which has a long retention time and which has a short
Alcohols: They're out fast! Since they're polar and love hydrogen bonds, they don't stick to the nonpolar surface.
Esters: They take a bit longer. They're polar but don't strongly bond with hydrogen-like alcohols, so they interact with the surface via LDFs (London dispersion forces). Similar esters will behave similarly, primarily based on their size and boiling point.
Alkanes: They stick around longest. It's a like-dissolves-like thing; they have strong London dispersion forces (LDF).
Imagine the surface is greasy. Alkanes stick like glue. Esters are slightly less sticky, and alcohols tend to evaporate as soon as possible since they are water-like.
Here is my 2 cents!
(edited 10 months ago)
Reply 2
Original post
by fantasticbunnyPlease help!
A sample contains a mixture of two esters contaminated with an alkane and an alcohol. Suggest how well these four compounds would be separated using an alkane stationary phase. In your answer, include some indication of the length of the retention times. Explain your answer.
The answer is The esters would have similar retention times AND similar structures/molecules OR same functional groups OR similar polarities OR similar solubilities. Alcohol would have a short retention time AND alkane would have a long retention time
I dont understand how to distinguish between which has a long retention time and which has a short
A sample contains a mixture of two esters contaminated with an alkane and an alcohol. Suggest how well these four compounds would be separated using an alkane stationary phase. In your answer, include some indication of the length of the retention times. Explain your answer.
The answer is The esters would have similar retention times AND similar structures/molecules OR same functional groups OR similar polarities OR similar solubilities. Alcohol would have a short retention time AND alkane would have a long retention time
I dont understand how to distinguish between which has a long retention time and which has a short
I think it’s to do with polarity because the solvent will be polar so substances that are more polar will be more attracted to the solvent so shorter retention time.
Reply 3
20
Original post
by LittleFire10I think it’s to do with polarity because the solvent will be polar so substances that are more polar will be more attracted to the solvent so shorter retention time.
The OP states that there is "an alkane stationary phase". Alkanes are non-polar. Non-polar components in the mixture will be attracted to the stationary phase more strongly and will hence take longer to get through the pipe.
Polar components in the mixture will not be attracted and hence will stay (mostly) on the move and have a short retention time.
Reply 4
13
Original post
by fantasticbunnyPlease help!
A sample contains a mixture of two esters contaminated with an alkane and an alcohol. Suggest how well these four compounds would be separated using an alkane stationary phase. In your answer, include some indication of the length of the retention times. Explain your answer.
The answer is The esters would have similar retention times AND similar structures/molecules OR same functional groups OR similar polarities OR similar solubilities. Alcohol would have a short retention time AND alkane would have a long retention time
I dont understand how to distinguish between which has a long retention time and which has a short
A sample contains a mixture of two esters contaminated with an alkane and an alcohol. Suggest how well these four compounds would be separated using an alkane stationary phase. In your answer, include some indication of the length of the retention times. Explain your answer.
The answer is The esters would have similar retention times AND similar structures/molecules OR same functional groups OR similar polarities OR similar solubilities. Alcohol would have a short retention time AND alkane would have a long retention time
I dont understand how to distinguish between which has a long retention time and which has a short
which exam board is this?
Reply 5
Hi thank you for all of your replies! I appreciate the help everyone! 
Reply 6
Original post
by pspspspwhich exam board is this?
This is for ocr a
Reply 7
13
Original post
by fantasticbunnyThis is for ocr a
phew
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