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September 21, 2014

Search: TLC

Number of results: 86

Chemistry!!!
1.)The silica that makes up the stationary phase in TLC chromatophraphy is more polar than the mobile phase. What then might the relative positions of the analgesics on the developed TLC plate tell you about the polarity of these molecules? Does this match the expectations ...
July 1, 2013 by Kris

chemistry
How can you tell which mobile phase is more polar in TLC? (hexane/ethyl acetate/ethanol vs. isopropanol/ammonia)? the hexane/ethyl acetate/ethanol travelled up the TLC faster, does this make it more polar? The TLC is silica gel!
September 28, 2009 by L

TLC error
When a TLC plate was developed, the solvent front ren off the top of the plate. why?
September 30, 2008 by jane

Organic Chem
What is the problem of spotting TOO much sample on a TLC plate initially? Also, why is it bad to have too much solvent in the TLC jar?
May 9, 2011 by Jim

chemistry
Q#1:what would you look for in a tlc experiment to determine whether or not your sample was pure? Q#2:could you determine the extent to which your sample may be contaminated with the tlc technique?
November 13, 2012 by Anonymous

Chemistry - thanks
In a thin layer chromatography (TLC)experiment,the TLC plate was pre-developed in the development chamber containing the mobile phase (to remove any contaminants before use),then air dried. On the same day,the TLC plate was then spotted with the sample & standard and placed in...
January 31, 2012 by Anne

Thin Layer Chromotography
Can you use TLC to distinguish various isomers from one another? In what kind of substance can you NOT distinguish the isomers from each other? i think it is not possible to distinguish If I have an unknown sample containing several ketones and want to use TLC to identify the ...
November 5, 2006 by Sarah

science(chemistry)
I have a question about TLC plate solvents. What solvents will leave stains on a plate with a TLC plate out of the ones below and why?) (n-Octane, n-Hexane, Decane, Acetone, 1-Propanol, 2-Propanol, Ethanol, Toluene, Cyclohexane, Methanol, n-Heptane, n-Pentane, Butanol) I saw 2...
April 24, 2009 by ~christina~

Chemistry
You and another student were each given an unknown compound. Both samples contained colorless material. You each used the same brand of commercially prepared TLC plate and developed the plates using the same solvent. Each of you obtained a single spot of Rf=0.75. Were the two ...
February 2, 2010 by Judy

chemistry
How can you tell which mobile phase is more polar in TLC? (hexane/ethyl acetate/ethanol vs. isopropanol/ammonia)? the hexane/ethyl acetate/ethanol travelled up the TLC faster, does this make it more polar?
September 28, 2009 by L

Chemistry-help needed
I have a question on thin layer chromatography (TLC). My mobile phase (i.e. developing solvent) is a mixture of 2 non-polar solvents. After preparing the mobile phase, is it necessary to pour some into the developing chamber to saturate the chamber or should we only pour the ...
January 31, 2012 by Anne

chem
The Rf value of compound A is .34 when the TLC plate is developed in hexane and .44 when the plate is developed in diethyl ether. Compound B has an Rf value of .42 in hexane and .60 in diethyl ether. Which solvent would be better for seperating a mixture of compounds A and B ...
October 21, 2008 by Jason

Chemistry
Consider the following errors that could be made when running TLC. Indicate what should be done to correct the error. a) a two-component mixture containing 1-octene and 1,4-dimethylbenzene gave only one spot with an Rf value of .95. The solvent uses was acetone. b) a two-...
October 3, 2010 by Jordyn

chemistry
How are the spots on the TLC plates observed?
March 29, 2012 by mzrins

chemistry
How to know if in TLC and HPLC if it is going forward or reverse?
December 1, 2010 by Ben

Chemistry
Consider the following errors that could be made when running TLC. Indicate what should be done to correct the error. a) a two-component mixture containing 1-octene and 1,4-dimethylbenzene gave only one spot with an Rf value of .95. The solvent uses was acetone. b) a two-...
October 9, 2008 by Nina

Chemistry/ OChem
Consider the following errors that could be made when running TLC. Indicate what should be done to correct the error. a) a two-component mixture containing 1-octene and 1,4-dimethylbenzene gave only one spot with an Rf value of .95. The solvent uses was acetone. b) a two-...
October 9, 2008 by Neets

science(chem)
[b]1.[/b]Is TLC a qualitative or quantitative analysis? Is there any way that it can be both? Explain. ~I say it can be both since it can be used to go and determine what exactly is in a sample of mixed compounds which would be qualitative analysis. It can also be quantitative...
October 13, 2007 by ~christina~

pharmacy
suggest a technique , other than tlc, to confirm the purity of the samples
April 19, 2012 by pavan

Mobility and Rf
We did a column chromatography then a TLC on extracted spinach pigments. Question: Why are the chlorophylls less mobile on column chromatography and why do they have lower Rf values than the carotenes? My answer: The chlorophylls are more polar than the carotenes so they ...
October 22, 2006 by Sheryl

Chemistry
Can anyone please tell me what can you say about the purity of the compound extracted based on your TLC results? Thanks
February 9, 2010 by Andy

Organic Chemistry
Why would the presence of crystals of sample at the starting line cause streaking on a TLC plate?
March 19, 2012 by Sally

Sample purity
Question: A student spots an unknown sample on a TLC plate and develops it in pentane solvent. Only one spot, for which the Rf value is 0.05, is observed. Is the unknown a pure compound? What can be done to verify the purity of the sample using TLC? My answer: It's not ...
October 15, 2006 by Sheryl

Organic Chemistry Lab
How do we correct the problem if during TLC development the solvent ran off the plate?
October 21, 2010 by Jeanne

Chemistry
List in increasing order of expected Rf values in a TLC experiment: salicylic acid, toluene, and benzophenone.
July 1, 2013 by Kris

science(chemistry)
I have a question about solvent evaporation. If I had an organic layer and an aqueous layer in an unknown mixture of liquids and wanted to obtain the solid of a compound(s) dissolved in the layers, is it reasonable to assume that I can run the compound in the IR spectrometer (...
April 17, 2009 by ~christina~

Organic Chemistry
Thin Layer chromatography TLC experiment What does it mean when it says with to much sample the spots will tail
October 26, 2012 by Nathalie

chemistry
why we just see a light spot of benzaldehyde after tlc in iodine chamber which soon vanishes and does not appear again?
August 20, 2011 by manoj

Purity
The question asked is: Using yur results as a guide, comment on the purity of the material in the green and yellow bands. (from a TLC of spinach extraction pigments.) I'm not quite sure what they want here and my plate is in the lab, not here. There were yellow and green bands...
October 22, 2006 by Sheryl

chemistry
why do different compounds give different retention factors (Rf values) in thin layer chromatography (TLC)
April 30, 2013 by jessica

TLC purity
Question: A student spots an unknown sample on a TLC plate and develops it in dichloromethane solvent. Only one spot, for which the Rf value is 0.95, is observed. Does this indicate that the unknown material is a pure compound? What can be done to verify the purity of the ...
October 13, 2006 by Sheryl

Chemistry
How do i calculate plate number, distribution constant, mobile phase and stationary phase volume for tlc not HPLC/ GC
July 27, 2011 by Pharmacy

Spinach
I did a column chromatography on spinach and then a TLC. On the TLC I got five visible bands of colors. On the extracted yellow substance I got one yellow band (carotene) and on the green I also got only one green band. I thought there would be more bands on the green but ...
October 23, 2006 by Sheryl

chemistry
see if on tlc silica if the polar solvent moves slowly then does even polar substances rf value is low? and the nonpolar rf is high?
February 23, 2010 by KKSAI

Chemistry
suppose you carry out a TLC separation of acetaminophen and phenacetin on silica gel using a non polar developing solvent. which should have a higher Rf value, and why?
October 21, 2009 by Anonymous

accounting
how can i tell which users are internal or external? like bank mangaer parent owner toy suppier cleaner contracted by tlc daycare canada customs and revenus agency
October 4, 2008 by Anonymous

Organic Chemistry
Identify the error in the following scenario and indicate how you would fix the error: A TLC of a two component mixture of pentene and 1,3-diethylbenzene was run in acetone. An Rf value of 0.90 was reported.
October 28, 2012 by Sarah

Organic Chemistry 1
Why does iodine absorb organic molecules? This question is referring to the effect of the iodine chamber used in TLC.
October 24, 2008 by Audrey

TLC error correction
Question: Consider the following errors that could be made when running TLC. Indicate what should be done to correct the error. A. 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. In ...
October 14, 2006 by Sheryl

science(chem)
Consider the following errors that could be made when running the TLC. Indicate what should be done to correct the error. a) A 2 component mixture containing 1-octene and 1,4- dimethylbenzene gave only 1 spot with and Rf value of 0.95. The solvent used was acetone b) A 2 ...
October 8, 2007 by ~christina~

ochem lab
this deals with TLC chromatography: if 2 compounds have same Rf under identical conditions, does it show that they have identical structures? i think it does. but im not sure why. thanks mucho.
November 2, 2007 by christine

organic chemistry
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 would you perform?
October 17, 2012 by lili

Organic Chem Lab
If I have separate solutions of the compounds benzoic acid and benzaldehyde, and they are spotted on an alumina gel TLC plate and run using CH2Cl2 as the eluant, which compound will have the higher Rf value? Explain.
October 11, 2009 by Sarah

TLC peru balsam
what is the rf value for peru balsam in order of identification?
September 14, 2009 by ira

Ochem Lab
why is it important to spot samples directly on the marks made on the TLC plate? This is for Thin Layer Chromotography. Is this important so that the solvents move directly up the plate and can be identifies easily? Thanks
October 24, 2010 by Adam

Lab conclusion- HELP!
I' am currently trying to wrie a couple of lab conclusions and having a hard time coming up with good points to make for the following lab experiment: Thin layer chorotography If anyone has a few minutes to give me a couple tips on how to improve this. I think it sounds like a...
February 5, 2007 by Richard

Chemistry
Chromatography How can I tell which of two mobile phases is more polar? Does the fact that one solvent (e.g. isopropanol/ammonia) moves up the TLC plate slower than another solvent (e.g. hexane/ethyl acetate/ethanol)? Or should I look at how far up the dyes have moved?
September 26, 2008 by Jeannie

Chemistry
Chromatography How can I tell which of two mobile phases is more polar? Does the fact that one solvent (e.g. isopropanol/ammonia) moves up the TLC plate slower than another solvent (e.g. hexane/ethyl acetate/ethanol)? Or should I look at how far up the dyes have moved?
September 26, 2008 by H

A&P II
I have 2 problems/questions I am unsure of the answers. The first one is "how would you demonstrate the Valsalve maneuver using the model lung?" and 2. If a woman is breathing rapidly and deeply after exercise, would TLC, RV, TV, IRV, and ERV stay the same, increase or ...
March 11, 2012 by Mary

anatomy
I have 2 problems/questions I am unsure of the answers. The first one is "how would you demonstrate the Valsalve maneuver using the model lung?" and 2. If a woman is breathing rapidly and deeply after exercise, would TLC, RV, TV, IRV, and ERV stay the same, increase or ...
March 12, 2012 by Mary

TLC
The following two solvents systems were found to separate compounds x and y by flash column chromatography: X- hexanes/ethyl acetate 10:1 Y- hexanes/ethyl acetate 10:4 which is more polar X or Y? Which solvent system must be used first?
February 18, 2007 by sue

Biology Question
I have 2 problems/questions I am unsure of the answers. The first one is "how would you demonstrate the Valsalve maneuver using the model lung?" and 2. If a woman is breathing rapidly and deeply after exercise, would TLC, RV, TV, IRV, and ERV stay the same, increase or ...
March 11, 2012 by Mary

chemistry
-Suppose you carry out TLC separation of acetaminophen and ibuprofen on silica ggel using a nonpolaar developing solvent. which should have a higher Rf? -Assuming that the drug components whose spots you identified dissolved completely when you stirred the tablet with 1:1 ...
November 29, 2010 by tristan

biology
I have 2 problems/questions I am unsure of the answers. 1. how would you demonstrate the Valsalve maneuver using the model lung? 2. If a woman is breathing rapidly and deeply after exercise, would TLC, RV, TV, IRV, and ERV stay the same, increase or decrease? Thank you for any...
March 13, 2012 by Wendy

chemistry
For a TLC lab,the stationary phase is the mixture of isopropanol and ammonia or the mixture of hexane,ethyl acetate and ethanol, the stationary phase is silica gel. text some dyes and drugs. what is the relationship between the polarity of molecules and the Rf values?
September 28, 2010 by Leon

chemistry
In TLC, why do you spot multiple times? Select one or more correct answers. A. To fill the capillary almost instantly by capillary action. B. So the developing chamber solvent does not evaporate. C. The higher compound concentration facilitates visualization. D. To acheive a ...
August 18, 2012 by Hannah

Difference?
What is the difference between these two questions? They look the same to me, like they're asking the same thing. Not likely. Question: A student spots an unknown sample on a TLC plate and develops it in dichloromethane solvent. Only one spot, for which the Rf value is 0.95, ...
October 14, 2006 by Sheryl

chemistry
out of orthonitroaniline and paranitroaniline which one will go at the top of TLC plate and why It depends upon the stationary phase and the mobile phase, to some extent; however, o-nitroaniline is LESS polar than p-nitroaniline. A polar adsorbent will hold the para isomer ...
April 9, 2007 by pawam

college chemistry
If i have a highly polar mobile phase, what will happen to the non-polar or less polar compounds during chromatography? will they move less up the TLC plate or actually even more because the mobile phase itself is so polar.
February 12, 2013 by Anonymous

ochem
Consider a sample that is a mixture composed of biphenyl, benzoic acid, and benzyl alcohol. Predict the order of elution of the components in this mixture on the TLC plate when solvent system a, b or c is used. a)Cyclohexane: Methylenechloride:100%:0% b)Cyclohexane: ...
May 7, 2013 by bez

Organic Chemistry
What is/are the product(s) of the potassium permanganate reaction with (R)-4-methyl cyclohexene? Is the product a meso molecule, racemic mixture, or other mixture, and if so, what kind of mixture? If the product is a mixture, do you expect the compounds to have the same or ...
October 31, 2010 by Anonymous

Thin layer chromatography
I've done some TLC plates using ethyl acetate with 0.5% glacial acetic acid as a solvent. The structure of these substances looks polar to me. I"m assuming that ethyl acetate is not very polar. Is this correct? Acetaminophen barely travelled any distance while aspirin went 2/...
October 18, 2006 by Sheryl

Chemistry
Each of the solvents given should effectively separate of the following mixtures by TLC. Match the appropriate solvent with the mixture that you would expect to separate well with the solvent. Select your solvent from the following: hexane, methylene chloride, or acetone. (a) ...
October 9, 2008 by Nina

Solvents
Question: When a TLC plate ws developed, the solvent front ran off the top of the plate. What should be done to correct the error. Me: The only reason I'm giving you this question to check is that it seems too simple. My answer would be to stop development before the solvent ...
October 15, 2006 by Sheryl

Chemistry
Assume your sample spots are 1 cm above the bottom of the TLC plate. What happens if you put the plate in a developing chamber that has 1.2 cm of developing solvent? A. The solvent will move up the plate by capillary action faster. B. The sample spots will become more ...
August 18, 2012 by JEN

Identical compounds?
Question: You and another student were each given an unknown compound. Both samples contained colorless material. You each used the same brand of commercially prepared TLC plate and developed the plates using the same solvent. Each of you obtained a single spot of Rf = 0.75. ...
October 13, 2006 by Sheryl

CHEMISTRY
In TLC, why do you spot multiple times? Select one or more correct answers. A. To fill the capillary almost instantly by capillary action. B. So the developing chamber solvent does not evaporate. C. The higher compound concentration facilitates visualization. D. To acheive a ...
August 19, 2012 by Hannah

rf value of lycopene
Is the the rf value of lycopene and with what solvent can you use as a mobile phase on a TLC? I don't know the answer here but I looked on the Internet and found something that may get you started. I found the Rf value for lycopene to be between 0.4 and 0.6 and the best mobile...
February 19, 2007 by paul

chemistry
For a TLC lab,the stationary phase is the mixture of isopropanol and ammonia or the mixture of hexane,ethyl acetate and ethanol, the stationary phase is silica gel. text some dyes and drugs. which one of the two mobile phases is the more polar? Actualy I need two pieces of ...
September 29, 2010 by Leon

Organic Chemistry
I just finished an organic chemistry lab experiment on separating and analyzing an unknown acid/neutral compound mixture using extraction, recrystallization, TLC, melting point analysis, and IR spectrum. In the instructions, "Obtain an IR spectrum for each of your ...
December 6, 2010 by Kate

Organic Chemistry Lab
ISOLATION OF CHLOROPHYLL AND CAROTENOID PIGMENTS FROM SPINACH: What would happen to the Rf values of the pigments if you were to increase the relative concentration of acetone in the developing solvent ? I said the Rf values would be higher because Acetone is more polar than ...
March 21, 2010 by Chinma

Concentration increase
Question: What would happen to the Rf values of the pigments if you were to increase the relative concntration of acetone in the developing solvent? Note: The development solvent used was 70% hexane - 30% acetone. My answer: Acetone is more polar than hexane so the increase in...
October 22, 2006 by Sheryl

list of rf values
can you give a comprehensive list of rf values. rf: Radio Frequency? I am uncertain what the context of rf is. rf probably is related to chromatography. They are the retention factors for thin layer chromatography; i.e., TLC. I looked on www.google.com an this is what I found...
December 7, 2006 by damola

Chemistry/ OChem
Each of the solvents given should effectively separate of the following mixtures by TLC. Match the appropriate solvent with the mixture that you would expect to separate well with the solvent. Select your solvent from the following: hexane, methylene chloride, or acetone. (a) ...
October 9, 2008 by Neets

science(chem)
Concerning TLC plates... 1. why should't I allow the solvent to reach the top of the plate? (I assume it's the same as using paper like I did in gen chem but I'm not sure I know why it shouldn't be allowed to reach the top... what would happen?) 2. why sholdn't the spot sample...
September 27, 2007 by ~christina~

Organic Chem.
When a tlc plate was developed the solvent front ran off the top of the plate, why? A two component mixture containing a dicarboxylic acid and tricarboxylic acid gave only one spot with an Rf value of 0.05. Solvent used; hexane. What went wrong? Solvent runs off the top ...
February 5, 2007 by Richard

Science - Chromatography
I performed a TLC of plant pigments in my lab class with a solvent of petroleum ether/ acetone (7:3) and used a silica gel plate. It is expected that the most polar pigments (chlorophyll) will be located near the bottom and the carotenoids near top. In my experiment, it was ...
October 5, 2008 by Veronica

chemistry
One afternoon, a graduate student set up a silica gel column to chromatograph a mixture of two colourless products whose Rf values were quite close. Suddenly, he realized that he had tickets to the Leafs game that night. He turned the stopcock to stop collecting eluent, put a ...
November 1, 2009 by lisa

Solvents
Question: Each of the solvents given should effectively separate one of following mixtures by TLC. Match the appropriate solvent with the mixture that you would expect to separate well with that solvent. Select your solvent from the following: hexane, methylene chloride, or ...
October 14, 2006 by Sheryl

Analgesics
We're doing a TLC analysis of analgesic drugs. One of my prelab questions is: Name some advantages of using acetaminphen (Tylenol) instead of aspirin as an analgesic. They were probably dissolved in methylene chloride amd ethanol and I'm assuming that's because one of these is...
October 12, 2006 by Sheryl

Rf values
Question: Consider a sample that is a mixture composed of biphenyl, benzoic acid and benzyl alcohol. The sample is spotted on a TLC plate and developed in a dichloromethane-cyclobutane solvent mixture. Predict the relative Rf values for the three components in the mixture. (...
October 14, 2006 by Sheryl

science (chem)
consider a sample that is a mixture of biphenyl, benzoic acid, and benzyl alchohol. The sample is spotted on a TLC plate and developed in a methylene chloride cyclohexane mixture. Predict the relative Rf values for the three components in the sample. For assistance use the ...
October 13, 2007 by ~christina~

science (chem) Rf values
consider a sample that is a mixture of biphenyl, benzoic acid, and benzyl alchohol. The sample is spotted on a TLC plate and developed in a methylene chloride cyclohexane mixture. Predict the relative Rf values for the three components in the sample. For assistance use the ...
October 14, 2007 by ~christina~

More spots
Question: A colorless unknown substance is spotted on a TLC plate and developed in the correct solvent. The spots do not appear when visualization with a UV lamp or iodine vapors is attempted. What could you do to visualize the spots if the compound is the following: C. An ...
October 15, 2006 by Sheryl

Visualizing spots
Question: A colorless unknown substance is spotted on a TLC plate and developed in the correct solvent. The spots do not appear when visualization with a UV lamp or iodine vapors is attempted. What could you do to visualize the spots if the compound is the following: My answer...
October 15, 2006 by Sheryl

Coordination
Is coordination the same as ionic bonding? Sheryl As I understand coordination, as in coordination number, no. It is more covalent or more precisely called coordinate covalent if we are talking abouat the same thing. Then I guess 'salt formation' would be referring to ionic ...
October 21, 2006 by Sheryl

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