On a chromatogram the solvent front moved 9.0 cm from the starting line…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
On a chromatogram the solvent front moved from the starting line. Chlorophyll a moved and chlorophyll b moved . (a) Find the Rf value of each. (b) Which has the higher Rf? (c) Can an Rf value be larger than ? Say why.
Need a reminder? The key ideaShow
Pigments: chlorophyll a (bright or blue green), chlorophyll b (yellow green), xanthophylls (yellow), carotenoids (yellow to yellow-orange). . Chlorophyll a absorbs best in blue and red. The action spectrum follows the absorption spectrum but is higher where accessory pigments add their light, and accessory pigments also protect chlorophyll a from photo-oxidation.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Chlorophyll a. .
Step 2. Chlorophyll b. .
Step 3. Compare. , so chlorophyll a has the higher Rf.
Step 4. The limit. The pigment moves only because the solvent carries it. It cannot get ahead of the solvent front, so Rf is always less than .
Answer: (a) and ; (b) chlorophyll a; (c) no, a pigment cannot move farther than the solvent.
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