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Chemistry, 15.04.2020 00:37 letsgetcookingblog

Chromatography A TLC of a mixture of three compounds, B (Rf = 0.1), C (Rf = 0.3), and A (Rf = 0.5) was run in 50% hexanes:50% ethyl acetate as the eluent. A column was done to separate the three spots also using 50% hexanes:50% ethyl acetate as the eluent. 1. Which spot (A, B or C) would come off the column first? (2 points) 2. Which spot (A, B or C) would come off the column second? (2 points) 3. Which spot (A, B or C) would come off the column last? (2 points) The solvent mixture that ran through the column was collected into 3 different beakers. After analysis, it was determined that the first beaker contained only the fastest-moving spot. The second beaker contained a mixture of the fastest moving and second-fastest moving spots. The third beaker contained only the second-fastest moving spot. 4. Draw the TLC that you would see if you took a sample from the second beaker and spotted a TLC and ran the TLC in 50% hexanes:50% ethyl acetate as the eluent. Make sure and label the spots (A, B or C) with their Rf. (4 points) 5. The slowest moving spot wouldn't come off the column with the 50% hexanes:50% ethyl acetate mixture. Which solvent would be more likely to make the slowest-moving spot run down the column faster, 100% hexanes or 100% ethyl acetate solution? (2 points). 6. Explain your solvent choice in #5 (why would that solvent make the slowest-moving spot move faster?). (3 points).

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Chromatography A TLC of a mixture of three compounds, B (Rf = 0.1), C (Rf = 0.3), and A (Rf = 0.5) w...
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