Science Buddies: "Ask an Expert"

Thank you for your help. I have another question. I conducted my candy experiment with three different solvents: salt water, isopropyl alcohol and vegetable oil. Is it right to assume that the Rf values for the best solvent will be higher than the other ("not as good") solvents?
My hypothesis is that, " If salt water, isopropyl alcohol, and vegetable oil are used as solvents, then salt water will be the best solvent, making the dyes travel the most distance and therefor have the highest Rf value."

If I have my chemistry correct (it's a bit rusty, I haven't done anything real with chemistry in over 20 years) the Rf value depends on both the thing being dissolved and the thing you are dissolving it in (solute and solvent).

So something might have a high Rf value for sugar but a low Rf value for salt.

Assuming you are talking about only one kind of solute (sugar, candy), than the "Candy Rf" value will of course be higher for the best solvent of sugar, by definition - the definition of higher Rf is that the better solvent makes the solute move further on the paper.

If you're reading Rf off a chart without respect to the thing being dissolved, it doesn't have any real meaning. At least that's how my memory works and what a quick refresher on the technique and term seems to lead me to.

I think your hypothesis is technically ok - you are saying you expect salt water to be the best solvent and therefore have a better sugar RF value. What I don't see in your hypothesis is why you expect it to be the best solvent.