Question

You are given a sample of several compounds to separate by paper chromatography. You draw a pencil line exactly 1.00 cm from the bottom of the paper, and place a spot of sample on it. You dry the sample, then develop it in a solvent. When the chromatogram is taken out of the solvent, the paper is wet up to 9.2 cm from the bottom of the sheet. The compound you are interested in shows up as a spot 7.1 cm from the bottom of the paper. Calculate the following:

a. How far did the compound move?
b. In the same time, how far did the solvent move?
c. What is the Rf factor for the compound?

Answer 1

a) 6.3 cm

b) 8.0 cm

c) 0.7875

Step-by-step explanation:

(a) The compound has moved above upto 7.3 cm from the bottom of the paper. Let us assume that line is drawn at 1.0 cm mark as the origin of spot. \

Distance traversed by compound= 7.3 - 1.0 cm = 6.3 cm

(b) Distance traversed by the solvent = 9.0 - 1.0 cm = 8.0 cm

(c) The Rf = Compound Migration distance / Solvent front migration distance

= 6.3/8.0 = 0.7875