Chromatography is the process or technique to separate a mixture. In this case the lab was separating the pigments in different leaves. The molecules move up the paper at different rates because of the difference in solubility, molecular mass, and hydrogen bonding with the paper. The purpose of the paper was to show the separation of pigments and the purpose of the solvent was to move the pigments up the paper through capillary action. After chromatography the bands on the paper can be assigned a relative mobility factor (Rf), which is the ration of the differences of the substances’ distances. An Rf value is useful to scientists because the value shows the different pigments using a value.
EQUATION:
Rf= distance solute traveled (D unknown)/ Distance traveled by solvent (D solvent)
The solvent front is the same as the D solvent and the shorter line that goes to the solute is the D unknown. This lab helped identify and explain the different pigments and how the pigments affects leaves at a certain time of year. The pigments present in leaves are chlorophyll a or b, xanthophyll and carotene. These all produce a certain color which was seen on the strip. In the green leave there were three pigments present: chlorophyll a and b and xanthophyll (seen in picture below). In the experiment we started by getting the pigment onto the paper and then obseriving as the pigment spread out. In order to get the best results the paper needs to stay in the isoproyol acid for a while. The purple leaf had the carotene, chlorophyll a or b, and xanthophyll all present in the leaf. The purple leaf clearly had little production of chlorophyll compared to the all green leaf. In the pictures below the pigment is spreading out as the paper sits in the alcohol.
In this video the experiment conducted is similar to the one performed in the pictures above. They both demonstrate the different leaf pigments and why leaves change color in the fall.
I would like to know what else chromatography can be used for.
Video from youtube All pictures except for the equation taken by me “Leaf Color Chromatography – Bite Sci-zed.” YouTube. YouTube, n.d. Web. 06 Oct. 2014. <https://www.youtube.com/watch?v=qH-AJDqsSII>. http://www.assignmentpoint.com/wp-content/uploads/2013/03/rf.jpg
Shauna O'Donoghue 
