Which of the following best describes how thin layer chromatography (TLC) can be used to aid in the identification of a compound?

• A. By determining the compound's solubility in water using the TLC plate.
• B. By measuring the boiling point of the compound after separation.
• C. By observing the color change of the compound when exposed to UV light before chromatography.
• D. By comparing the R_f value of the unknown compound to the R_f values of known standards under the same conditions.

Answer: (D)

Verified step by step guidance

1. Understand that Thin Layer Chromatography (TLC) is a technique used to separate components of a mixture based on their different affinities for the stationary phase (the TLC plate) and the mobile phase (the solvent).
2. Recognize that each compound travels a certain distance up the TLC plate depending on its polarity and interaction with the solvent and stationary phase, which is quantified by the retention factor, \(R_f\).
3. Calculate the \(R_f\) value for a compound using the formula: \(R_f = \frac{\text{distance traveled by the compound}}{\text{distance traveled by the solvent front}}\).
4. Use the \(R_f\) values as a characteristic property of compounds under specific conditions, meaning that compounds with the same \(R_f\) value under identical conditions are likely the same substance.
5. Compare the \(R_f\) value of the unknown compound to the \(R_f\) values of known standards run on the same TLC plate with the same solvent system to aid in identification.