Three compounds are analyzed by TLC first using petroleum ether as the solvent, then switching the...
- Three compounds are analyzed by TLC first using petroleum ether as the solvent, then switching the solvent to 95:5 petroleum ether-ethyl acetate. Will the order of elution change between the two solvent systems?
Yes or No
- Given the above information, how will the Rf values vary between the two plates?
| This cannot be predicted with the given information | |
| The compounds will have the same Rf values between the two plates | |
| The compounds will have greater Rf values for the second plate | |
| The compounds will have greater Rf values for the first plate |
Homework Answers
No
Order of elution change will not change between two solvent systems.
The compounds will have greater Rf values for the second plate.
It is due to the increase in the polarity of the eluent which will lead to enhance the capillary action force thus more Rf values.
Add Answer to:
Three compounds are analyzed by TLC first using petroleum ether
as the solvent, then switching the...
A.) What factors cause the order of elution to change? B.) If two unknown compounds are...
A.) What factors cause the order of elution to change? B.) If two unknown compounds are analyzed via thin-layer chromatography first using pure petroleum ether as the eluant and then 75:25 petroleum ether-ethyl acetate, how will the Rf values between plates change or can you not tell with the given information?
A student monitored the reaction progress of the reduction of 4-Nitrobenzaldehyde to 4-Nitrobenzyl alcohol using TLC....
A student monitored the reaction progress of the reduction of
4-Nitrobenzaldehyde to 4-Nitrobenzyl alcohol using TLC. 30% ethyl
acetate in petroleum ether was used as the elution solvent. TLC
plates available in the laboratory were coated with the common
absorbent silica gel (SiO2.xH2O) which
contains polar hydroxyl (OH-) groups.
c. The crude product moves slower
than the starting material with the mobile
phase in the TLC plate. Briefly
explain a possible reason for the
observation based on the chemical
structures...
Hi can someone help me with my pre lab theory questions (1,2,3) on rate of elution...
Hi can someone help me with my pre lab theory questions (1,2,3)
on rate of elution or Rf? Here is some background below. Please
help explain as many as possible (1-3)! I dont really get the
relation ships in this lab, thank you!
1. What factors affect the rate of elution in organic compounds? 2. Explain what is the relationship between polarities of compounds (polar/non- polar compound) and rate of elution (Rf). 3. Explain what is the relationship between solvent...
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...
Possible Quiz Questions 1 What two methods of visualizing spots on a TLC plate will you...
Possible Quiz Questions 1 What two methods of visualizing spots on a TLC plate will you use in this Give two reasons why would you predict that the elution solvents (hexanes or acetate) would not be visible under UV visualization? week's lab? ethyl 2. Define R 3. Calculate the R of the spot on the following TLC plate. 4. Which compound in each pair is predicted to have the higher Ri? a. CH3CH2CH2CH2OH and CH3CH2CH2CH28r b. CH3CH2CH2CH2OH and CH3CH2CH2CH2CH2CH2CH3 c....
2. A solution containing a mixture of naphthalene, benzoic acid, and benzaldehyde is analyzed via TLC...
2. A solution containing a mixture of naphthalene, benzoic acid, and benzaldehyde is analyzed via TLC and GC. Use the structures and properties of the compounds to aid in answering the following questions. A. In the TLC experiment, the mixture is spotted on a silica TLC plate and eluted with a 1:1 mixture of hexanes and ethyl acetate. Three spots are observed on the plate, with Re values of 0.25, 0.58, and 0.74. Indicate which spot corresponds to which compound....
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...
2. An unknown compound was analyzed using thin layer chromatography, its constituted of two components (A...
2. An unknown compound was analyzed using thin layer chromatography, its constituted of two components (A and B) as shown in the TLC (Silica coated stationary phase; Chloroform and Ethyl acetate as mobile phase). The mixture was then loaded onto column with silica as the stationary phase and the same solvent system was used. (2 points) Column Chromatography TLC time A В Predict the order of elution of the compounds (A and B). which one would be eluted first/last and...
CAN SOMONE PLEASE HELP. above is a picture of two TLC plates with spots on them....
CAN SOMONE PLEASE HELP. above is a picture of two TLC plates
with spots on them. could somone PLEASE PLEASE PLEASE help me get
their measurmentS (in milimeters) and help me calculate their Rf
values!!! I promise to rate u good if you could help!!! Im so
confused!!! THANK U SM
-solvent front scluent front Acetaminophen (A Afine (caf) Unknown mixture Phenacetin (Phn) Salicyamide (sal) Plate 2 Untuan unknown ixture mixture duplicate spots Plate 1 ASSIGNMENT In this experiment, TLC...
kindly answer the following thank you! 3. Since the surface of the silica gel on a...
kindly answer the following thank you!
3. Since the surface of the silica gel on a silica gel TLC plate is covered in SI-O-H groups, organic molecules that can hydrogen bond will be much more attracted to the silica gel surface. Given that which of the following compounds would have the lowest Rf value if each of these was analyzed using a slica gel TLC plate and dichloromethane as a solvent? OH 4. Determine the Rf values for the two...
A student monitored the reaction progress of the reduction of
4-Nitrobenzaldehyde to 4-Nitrobenzyl alcohol using TLC. 30% ethyl
acetate in petroleum ether was used as the elution solvent. TLC
plates available in the laboratory were coated with the common
absorbent silica gel (SiO2.xH2O) which
contains polar hydroxyl (OH-) groups.
c. The crude product moves slower
than the starting material with the mobile
phase in the TLC plate. Briefly
explain a possible reason for the
observation based on the chemical
structures...
Hi can someone help me with my pre lab theory questions (1,2,3)
on rate of elution or Rf? Here is some background below. Please
help explain as many as possible (1-3)! I dont really get the
relation ships in this lab, thank you!
1. What factors affect the rate of elution in organic compounds? 2. Explain what is the relationship between polarities of compounds (polar/non- polar compound) and rate of elution (Rf). 3. Explain what is the relationship between solvent...
Possible Quiz Questions 1 What two methods of visualizing spots on a TLC plate will you use in this Give two reasons why would you predict that the elution solvents (hexanes or acetate) would not be visible under UV visualization? week's lab? ethyl 2. Define R 3. Calculate the R of the spot on the following TLC plate. 4. Which compound in each pair is predicted to have the higher Ri? a. CH3CH2CH2CH2OH and CH3CH2CH2CH28r b. CH3CH2CH2CH2OH and CH3CH2CH2CH2CH2CH2CH3 c....
2. A solution containing a mixture of naphthalene, benzoic acid, and benzaldehyde is analyzed via TLC and GC. Use the structures and properties of the compounds to aid in answering the following questions. A. In the TLC experiment, the mixture is spotted on a silica TLC plate and eluted with a 1:1 mixture of hexanes and ethyl acetate. Three spots are observed on the plate, with Re values of 0.25, 0.58, and 0.74. Indicate which spot corresponds to which compound....
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...
2. An unknown compound was analyzed using thin layer chromatography, its constituted of two components (A and B) as shown in the TLC (Silica coated stationary phase; Chloroform and Ethyl acetate as mobile phase). The mixture was then loaded onto column with silica as the stationary phase and the same solvent system was used. (2 points) Column Chromatography TLC time A В Predict the order of elution of the compounds (A and B). which one would be eluted first/last and...
CAN SOMONE PLEASE HELP. above is a picture of two TLC plates
with spots on them. could somone PLEASE PLEASE PLEASE help me get
their measurmentS (in milimeters) and help me calculate their Rf
values!!! I promise to rate u good if you could help!!! Im so
confused!!! THANK U SM
-solvent front scluent front Acetaminophen (A Afine (caf) Unknown mixture Phenacetin (Phn) Salicyamide (sal) Plate 2 Untuan unknown ixture mixture duplicate spots Plate 1 ASSIGNMENT In this experiment, TLC...
kindly answer the following thank you!
3. Since the surface of the silica gel on a silica gel TLC plate is covered in SI-O-H groups, organic molecules that can hydrogen bond will be much more attracted to the silica gel surface. Given that which of the following compounds would have the lowest Rf value if each of these was analyzed using a slica gel TLC plate and dichloromethane as a solvent? OH 4. Determine the Rf values for the two...
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