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Lec: Chromatography. Chromatography is a physical process to determine what type of substances have been mixed together by separating them from one another.
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Chromatography is a physical process to determine what type of substances have been mixed together by separating them from one another.
Solubility is the rate (speed) at which a solute dissolves in the presence of a solvent. Solutes that have high solubility are known to dissolve very quickly. Solutes with low solubility dissolve very slowly.
Solutes which have the highest solubility will be the highest point on a piece of chromatography paper. The solute which has the lowest solubility will be on the bottom of the piece of chromatography paper.
The retention factor(Rf) is defined as the distance traveled by the solute divided by the distance traveled by the solvent.
Calculating the R factor(Rf)= Distance the Solute Traveled from Start Point Distance the Solvent traveled Finish Line
Example Problem Finish Line (Water) Yellow Dot Rf yellow = 6.8 /9.4 = 0.72 Rfblue = 3.4/9.4 = 0.37 6.8 cm Blue Dot 9.4 cm 3.4 cm Start/Ink Spot
Calculate the Rf for yellow and blue. Finish Line (Water) Yellow Dot 7.2cm Blue Dot 8.5cm 2.5 cm Start/Ink Spot
Calculate the Rf for yellow and blue. Finish Line (Water) Yellow Dot Rf Blue= 2.5/8.5 = 0.29 Rf Yellow= 7.2/8.5 = 0.85 7.2cm Blue Dot 8.5cm 2.5 cm Start/Ink Spot