More chromo

[sam0001]

When a mixture containing both ethanol and propanol is separated using HPLC with a polar stationary phas, which is likely to have the longer retention time? Explain your choice.

It doesn't specify the mobile phase at all. Suggestions?

[Tonychet2]

if the stationary phase is polar then the mobile phase will be non polar but this doesnt really matter

all u need to know in chromatography is polar bonds with polar and non polar bonds with non polar

since both are in the same homologous series.. alkanols, polarity does not matter,

in short, the shortest chain comes out first, so ethanol then propanol

therefore propanol has the larger retention time

[lalalo]

that seems right....
but what i thought was that since they are both of the same homologous series, the degree of polar bonds between each molecule and the stationary phase would not make a difference, but since propanol is slightly larger, couldn't it be the last to come out because it formed more stronger dispersion forces with the stationary phase...
i.e. the larger the molecule, the stronger the dispersion forces?