5. Consider a sample that is a mixture composed of biphenyl, benzoic acid, and b

Question

5. Consider a sample that is a mixture composed of biphenyl, benzoic acid, and benzyl n b alcohol. The sample mixture is spotted on a TLC plate and developed using dichloromethane-cyclohexane solvent mixture (mobile phase). Predict the relative Rr values for the three components in the sample. 6. A student spots an unknown sample on a TLC plate and developed it in dichloromethane (CH2Ch) solvent. Only one spot, with Rrvalue equal to 0.95, was observed. Does this indicate that the unknown material is a pure compound? Explain. How can you verify the purity of the sample.

Explanation / Answer

5. Rule: Rf will increase with decreasing polarity(polar compounds with the lowest Rf and nonpolar compounds with the highest Rf)

Biphenyl: nonpolar, being an unsaturated hydrocarbon

Benzyl alcohol: Slightly Polar

Benzoic acid: Polar carboxyl group

Hence Rf(Benzoic acid) < Rf(Benzyl alcohol)<Rf(Biphenyl)

Related Questions

Navigate

• Browse (All)
• Browse 5
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.