Question: Consider a sample that is a mixture composed of biphenyl, benzoic acid and benzyl alcohol. The sample is spotted on a TLC plate and developed in a dichloromethane-cyclobutane solvent mixture. Predict the relative Rf values for the three components in the mixture. (Hint: See Table 19.3 which gives elution sequence for compounds.)
My answer: I understand the order of Rf values and speed of travel. Seems like a guesstimate is in order as I'm not given any information about specific values. How about: Benzoic acid Rf about = .25; benzyl alcohol about = .50; biphenyl Rf about = .90.
Your answers are very helpful in pointing out my incorrect ways of evaluating the questions.
Sheryl
Rf value defined as the distance travelled by the elute divided by the distance travelled by the solvent
Rf value defined as the distance travelled by the elute divided by the distance travelled by the solvent
Rf value defined as the distance travelled by the elute divided by the distance travelled by the solvent
1 answer
In this case, the relative Rf values for the three components in the mixture can be determined by looking at the elution sequence for the compounds in Table 19.3. Benzoic acid would have the lowest Rf value, followed by benzyl alcohol, and then biphenyl with the highest Rf value.
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