JanuPExp001


 * What do the Rf values of the original Samples A-E suggest about the sample?**

From the Log of [|Exp 001], 1. Prepared a 50mL stock solution of 0.100g adrenaline, 5mL 1M sulfuric acid and methanol in a flask. 2. 14:47 Placed 1.86mL of adrenaline solution and 2.0mL 1M sulfuric acid in a round bottom flask. A 0.5mL sample of the starting reaction solution was pippetted out (sample A) and placed into a 1 dram vial. Attached the flask to a condenser and into a sand bath and turned the heat on low. 3.. TLC was performed on all samples of the reaction using methanol as the eluent.

sample A Rf= 0.338 sample B Rf= 0.571 The sample began to spread out. sample C Rf= 0.661 The sample continued to spread out. sample D Rf= 0.625 The sample is less spread out than previous samples. sample E Rf= 0.642

( The following data that was used to analyze this experiment is collected from this [|site]: )

- Retention factor, or Rf value, is the ratio of the distance the substance moved to the distance the solvent moved. - Dependent upon the polarity of the compound as well as the solvent, Rf values vary. - Since polar compounds have lower values than non-polar compounds, Sample A can validly proved to be the most polar of all the samples with a value of .338. - The more polar the sample is the slower it moves up the plate and thus causes for a lower Rf value. - Sample E thus is the most non-polar of the samples with a Rf value of .642. - Thus, Sample B-F are becoming increasingly non-polar with increasing Rf values. - In addition, the polarity of the solvent affects the Rf values as well. - Increased polarity causes for the spots to move farther up the plate. - The most effective separation is produced with a solvent that provides Rf values between .2 and .8. - Thus, the use of methanol can be figured out quickly. It produces Rf values of optimal value. - We have seen the demonstration of thin-layer chromatography in Chem 244 Lab (in Experiment 10) as well as understanding polar and non-polar properties in [|Lecture 7] that cause for the separation scheme of Samples A-E to have such Rf values.

( - The following observations are created without considering the effects of overloading, which can effect the Rf values and other external factors, which can cause the Rf values to be slightly skewed).

[|How to Calculate Rf Values]:



Rf = distance traveled by compound / distance traveled by solvent front


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