What problem would attend failure to mark the position of the solvent front on the TLC plate immediately after developing the plate?
What problem would attend failure to mark the position of the solvent front on the TLC...
A chemist runs a thin–layer chromatography (TLC) plate and, after development, forgets to mark the solvent front. The chemist doesn\'t realize this until the solvent has evaporated. Assuming that accurate Rf values are needed, select the correct course of action for the chemist. a. Assume that the solvent front is at the top of the plate. b. Dip the plate in phosphomolybdic acid (PMA) and heat the plate with a heat gun. c. Run the TLC analysis of these samples...
1. When 2-propanol was used as the developing solvent, two substances moved with the solvent front (Rf= 1) during TLC analysis on a silica gel plate. Can you conclude that they are identical? If not, what additional experiment(s) would you perform? 2. The Rf value of compound A is 0.34 when a TLC plate is developed in hexane and 0.44 when the plate is developed in diethyl ether. Compound B has an Rf value of 0.42 in hexane and 0.60...
3. If the TLC plate development had stopped before the solvent front reached the top of the TLC plate (i.e. maybe it reached the middle of the TLC plate when it was stopped, instead): a) Would the Rf values have been affected? If so, how? If not, why not? Give a numerical example to support your answer. b) Would the size of the spots have been affected? If so, how? If not, why not? (Hint: think about the diffusion of...
When 2-propanol was used as the developing solvent, two substances moved with the solvent front (Rf = 1) during TLC analysis on a silica gel plate. Can you conclude that they are identical? If not, what additional experiments(s) would you perform?
4)If you took a TLC of the would happen if you used the first eluting solvent as the developing solvent? What if you used the second eluting solvent? Draw a picture of each TLC plate as you think it would look original solution containing both β-carotene and chlorophyl, what 2 pts) β-carotene and chlorophyll in 30:70 acetone:pet ether β-carotene and chlorophyll in ethanol: Answer the following questions about conjugated double bonds and light absorption. d double bonds are necessary for...
2) During silica gel TLC analysis, when 2-propanol was used as a developing solvent, two substances moved with the solvent front (Rf = 1.0). Can you conclude that the substances are identical? If not, what additional experiment(s) would you perform? (5 pts).
Determine the Rf value of the substances A, B, and C on the TLC shown. Show your calculation! What will happen if the applied spot is lower than the level of the developing liquid? What will be the result of applying too much compound on a TLC plate? What is the reason that the mobile phase travels up the silica gel plate (TLC plate)? 4. Determine the Rf value of the substances A, B, and Con the TLC shown. Show...
1) A student develops their TLC plate and places it under a UV light, but nothing appears. What mistake might the student have made? a) Spotted the compound below the level of eluent b) Spotted the compound above the level of eluent c) Used a sample that was too concentrated d) Used too much sample 2)Thin layer chromatography, TLC, is commonly used to monitor reactions to completion. Using this technique, what would indicate to a student that the reaction is...
1) What error is introduced in determining the Rf value if the solvent is allowed to run after it reaches the height of the TLC plate? 2) What problem will occur if the pool of solvent (mobile phase) is at the level of the sample spots on the TLC plate?
1) What will be the appearance of a TLC plate if a solvent of too low polarity is used for the development? too high polarity?