Chromatography

[EyeAmLoz]

I have to design an experiment to do with paper chromatography..

The independent variable is up to us but it has to affect the Rf value of whatever we are testing..

I'm stuck trying to research what actually affects the Rf value besides from different solvents.

Does anyone know if the temperature of the solvent affects the Rf value???

A source would be perfect, but not necessary.

Thanks so much.

xxx

[Sublime Sunshine]

Paper Chromatography

There is a link to a forum where someone else has asked the same question.

If you scroll down, someone has mentioned:

Quote:

1. Identify three factors that might influence where on the chromatogram the pigments end up.

The filter paper, solvent and time is the three factors that might influence where the pigments end up on the chromatogram.

If you wanted to get bonus points, you could add "relative humidity" (paper soaks up water vapor from the atmosphere, so changing the humidity indirectly affects the chemical composition of the paper) and "temperature" (your pigments will interact with the paper and the solvent in a slightly different manner as a function of temperature).

EDIT: Even more

http://www.sciencebuddies.org/science-fair-projects/project_ideas/Chem_p009.shtml

It is very easy to make this project more advanced without doing much additional work. You could test how changing the pH of the water and/or changing the temperature of the solvents affects your results. For changes in temperature, do a few levels of temperature difference: refrigerated, room temperature, and warm (do not let the solvents get so hot they boil). Changing the level of pH is easy, just add a small amount of acid (diluted hydrochloric or sulfuric acid will work). Test the pH of the water with litmus paper, and try a variety of different acidic pHs (maybe a pH of 2, 4, and 7).

Edited October 14, 2010 by Sublime Sunshine