Question

QUESTIONS 1. In your own words, explain how the components of a mixture are separated during thin layer chromatography. Do not explain how to perform TLC; in other words do not explain the procedure. 2. Explain the purpose of the UV lamp in this experiment. 3. Why must you use pencil, not pen, when you make marks on the TLC plate? How do you know? Be sure to 4. Which substances were in the OTC pain reliever? discuss your Rr values and what you observed in the TLC plate in your explanation. 5. Based on your TLC results, did you in fact synthesize aspirin in a previous lab? How do you know? Be sure to discuss your Rf values and what you observed in the TLC plate in your explanation. 6. Do you see evidence of any impurities in the TLC for your crude aspirin sample? How do you know? 7. Copy the structural formulas of aspirin, acetaminophen, ibuprofen, naproxen, and caffeine. Circle and label the functional groups in each molecule. 8. What structural feature does caffeine lack that aspirin, acetaminophen, ibuprofen, and naproxen all have?

Answer 1

1.In TLC compounds are separated based on the principle of adsorption, their polarity and solubility of the compound.
When a mixture containing two compounds are run in TLC then the more polar compound binds the stationary phase more strongly than the less polar compound. Hence different compound travel at a different speed in the TLC plate and they get separated. Less polar compound travel more distance than the more polar compound in a particular solvent system.

2. UV lamp is required to see UV visible compounds' spots which are otherwise not visible via naked eyes

3. We must use pencil because pencil is made of graphite and it's not soluble in organic solvents whereas pen ink are organic mixture hence they will dissolve in solvents and spoil the TLC plate.