MediumChemistryHigh School (9–10)GeneralMixtures and Solutions › Separation of MixturesNumericalConceptual
Three known dyes have these Rf values in a solvent: dye A 0.25, dye B 0.48, dye C 0.82…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Three known dyes have these values in a solvent: dye A , dye B , dye C . An ink from a forged letter is run in the same solvent. The solvent rises , and the ink gives two spots, at and . Which dyes are in the ink?
Need a reminder? The key ideaShow
In chromatography, each dye is carried up the paper at its own speed. , measured from the starting line. It has no unit, lies between and , and identifies a substance in a given solvent.
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. The lower spot. : dye B.
Step 2. The upper spot. : dye C.
Answer: The ink is a mixture of dyes B and C. It has no dye A.
Check. The comparison is fair only because the ink and the known dyes were run in the same solvent.
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