Hi Natasha,

TLC runs off the idea that polar molecules will spend more time in the polar silica than they will in the nonpolar solvent and therefore will travel shorter distances up a plate than non polar compounds.

However, when you change from a less polar (hexane : diethyl ether) solvent to a more polar solvent (methanol), all compounds on the TLC are likely to spend more time in the solvent.

This because all compounds on a TLC have at least some affinity for the TLC plate itself, even if they are non polar. As a result, both compounds will move further up the plate, and that corresponds to B.

In other words, if you increase the solvent polarity, it's almost like changing what the environment looks like outside.


A COVID type metaphor for this:

If solvent is non polar, it's kind of like my work is far away and not comfy, so I stay at home in the silica gel. If the solvent is more polar, its' like my work is right in my room at home, and as a result I'm more likely to get up and do work, so I find I can get more done and I'll move further up the plate.

I hope this helps!

Katt

All compounds that are on the TLC would move further than they originally would have. As Katt had mentioned earlier, the compounds placed on the TLC have an intrinsic amount bonding to the TLC plate. With a change in solvent, it interrupts that bonding, for both compounds, to the TLC plate, which results in both compounds moving further up the plate.

Hope this helped! :)