I have two questions regarding TLC. 1.) What error is introduced into the determination of an...
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I
have two questions regarding TLC.
1.) What error is introduced into the determination of an...
1. Propose a synthesis for aspirin, Ibuprofen and acetaminophen. Start with benzene and any other reagents...
1. Propose a synthesis for aspirin, Ibuprofen and acetaminophen. Start with benzene and any other reagents that contain 4 or less carbons. 2. What error is introduced into the determination of an Rf value if the solvent front migrates to the top of the TLC plate? 3. Why is the TLC run in a closed chamber?
1) What error is introduced in determining the Rf value if the solvent is allowed to...
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?
Post lab questions for chromatography and melting point lab. i have a few ideas of what the answers to these questions s...
Post lab questions for chromatography and melting point lab. i
have a few ideas of what the answers to these questions should be,
but I would like to double check. if anyone can help me, that would
be so awesome. Thank you!
A student cools a sample in a capillary tube after melting it. Upon attempting to determine the melting point on the same sample, the student does not obtain the same melting point. Why? A student places his TLC...
Consider the following errors that could be made when running TLC. Indicate what should be done...
Consider the following errors that could be made when running TLC. Indicate what should be done to correct the error. A two-component mixture containing 1-octene and 1, 4-dimethylbenzene gave only one spot with an Rf value of 0.95. The solvent used was acetone. A two-component mixture containing a dicarboxylic acid and tricarboxylic acid gave only one spot with an Rf value of 0.05. The solvent used was hexane. When a TLC plate was developed, the solvent front ran off the...
3. If the TLC plate development had stopped before the solvent front reached the top of...
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...
1. Why should any marks on the TLC y marks on the TLC plate be done...
1. Why should any marks on the TLC y marks on the TLC plate be done in pencil and not pen? 2. A spot on a TLC plat migrates 4.2 cm as the solvent plates my migrates 4.2 cm as the solvent plates migrates 8.0 cm up the plate. What is the Rivalue for this spot? Show your calculati
1. A solution of the sample to be analyzed has been made in a suitable solvent...
1. A solution of the sample to be analyzed has been made in a suitable solvent and wil l be provided for you. With this solution, a small spot is applied at a distance hear the bottom of the edge of a TLC plate using an applicator. (see Figure 1) This spot must be above the level of solvent in the TLC chamber. Why? 2. The plate is placed in a developing chamber containing the appropriate solvent (eluent), covered, and...
Please help 2. Consider the TLC plate shown below that was done on silica gel using...
Please help
2. Consider the TLC plate shown below that was done on silica gel using a solvent mixture of 4:1 hexane/EtoAc as the eluent. 4:1 Hexane:EtOAC marked solvent front Spot B Spot A A origin (a) Which of the two organic compounds labeled A and B is less polar? (b) Calculate the Rf value of compound B. (c) How would the following changes affect the Rf values of A and B? i. Change to a more polar solvent mixture...
1. When 2-propanol was used as the developing solvent, two substances moved with the solvent front...
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...
5. Two unknown samples are spotted next to each other on a TLC plate. Development of...
5. Two unknown samples are spotted next to each other on a TLC plate. Development of the plate with ethyl acetate and visualization using UV light gives the following data: Spot 1: Rp = 0.65 Spot 2: Rp = 0.63 These two Rf values are so close that the difference might be due to experimental error (you're still learning TLC and not yet an expert in the technique). Describe an experiment that can be run using the same developing solvent...
Post lab questions for chromatography and melting point lab. i
have a few ideas of what the answers to these questions should be,
but I would like to double check. if anyone can help me, that would
be so awesome. Thank you!
A student cools a sample in a capillary tube after melting it. Upon attempting to determine the melting point on the same sample, the student does not obtain the same melting point. Why? A student places his TLC...
Consider the following errors that could be made when running TLC. Indicate what should be done to correct the error. A two-component mixture containing 1-octene and 1, 4-dimethylbenzene gave only one spot with an Rf value of 0.95. The solvent used was acetone. A two-component mixture containing a dicarboxylic acid and tricarboxylic acid gave only one spot with an Rf value of 0.05. The solvent used was hexane. When a TLC plate was developed, the solvent front ran off the...
1. Why should any marks on the TLC y marks on the TLC plate be done in pencil and not pen? 2. A spot on a TLC plat migrates 4.2 cm as the solvent plates my migrates 4.2 cm as the solvent plates migrates 8.0 cm up the plate. What is the Rivalue for this spot? Show your calculati
1. A solution of the sample to be analyzed has been made in a suitable solvent and wil l be provided for you. With this solution, a small spot is applied at a distance hear the bottom of the edge of a TLC plate using an applicator. (see Figure 1) This spot must be above the level of solvent in the TLC chamber. Why? 2. The plate is placed in a developing chamber containing the appropriate solvent (eluent), covered, and...
Please help
2. Consider the TLC plate shown below that was done on silica gel using a solvent mixture of 4:1 hexane/EtoAc as the eluent. 4:1 Hexane:EtOAC marked solvent front Spot B Spot A A origin (a) Which of the two organic compounds labeled A and B is less polar? (b) Calculate the Rf value of compound B. (c) How would the following changes affect the Rf values of A and B? i. Change to a more polar solvent mixture...
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...
5. Two unknown samples are spotted next to each other on a TLC plate. Development of the plate with ethyl acetate and visualization using UV light gives the following data: Spot 1: Rp = 0.65 Spot 2: Rp = 0.63 These two Rf values are so close that the difference might be due to experimental error (you're still learning TLC and not yet an expert in the technique). Describe an experiment that can be run using the same developing solvent...
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