[Vermilion]

Hey so i have question about RF values in eluting solvents.

So lets say i have a polar starting material and a non polar product.
And lets say our eluting solvent is non polar.

If i were to increase the concentration of polar compounds in my eluting solvent ≥ the non polar concentration, Would the Rf value of my starting material increase while the product remain the same? (Assuming my original eluting solvent was relatively nonpolar) or would the RF of the product go down?
 
I think the RF of the product would stay the same because it still has non polar solvent to carry it up the TLC plate its just now I wont be able to see the difference in product versus starting material because of them both being carried up the TLC plate.

Before the purpose of the TLC plate was to ensure we gained the non polar product we were trying to make.

But in terms of RF values, i still think the starting materials RF would be slightly smaller just because of the polarity of the silica gel, approximately only half of the polar stationary phase would be carried up the TLC plate and the other half would compete with the polar half of the eluting solvent. 

[Dan]

But in terms of RF values, i still think the starting materials RF would be slightly smaller just because of the polarity of the silica gel

Yes, generally speaking the affinity for these compounds for the stationary phase (silica gel) is the most important factor affecting the order of elution - the mobile phase affects the speed of elution, but not normally the order. If you increase the polarity of the mobile phase, the R_f of all components of the mixture will increase, but it is unusual (but not impossible) for one spot to overtake another.

approximately only half of the polar stationary phase would be carried up the TLC plate and the other half would compete with the polar half of the eluting solvent.

I don't understand this. The stationary phase (silica) is stationary - it doesn't move up the TLC plate.

[Vermilion]

Oohh what i meant was that the starting material, which is polar, would only move up the plate half as much as the non polar product because the starting material would compete with the silica gel since its polar. The only reason it would go up half at all is because of half the eluting solvent being polar, perhaps? Now the product would go up the full way because the product doesnt have that problem, regardless of the eluting solvent. I was trying to word that as a question and was unaware i used the stationary phase term wrong, now i know!
But im still curious to know if that is the case, whether it would move up half as much.