Lab 2- TLC

Column Chromatography Alumina Chromatography Mixture 9:1 Hexanes:Ether 8:2 Hexanes:Ether 1:1 Hexanes:Acetone Amount Used 3.962 g 0.143 g 9.50 mL 9.50 mL 11.00 mL Additional Observations (Color, etc.) BIU X₂ X² → BI IU X₂ X² → BI IU X₂ X² → BI IU X₂ X² → BIU X₂ X² →

Use a suitable model to explain how separation and identification of a mixture of organic compounds can be achieved with a thin layer chromatographic (TLC) technique.

anch of the following components cannot be detected by gas chromatography? 4 Essential oils Alcohols b) Volatile compounds d) Non-volatile compounds 13- is measured as time elapsed from the point of injection to the peak maximum? a)-Column efficiency d)- Delectability c)-Retention time 14- Which of the following can be used to detect the components in gas chromatography a) non-volatile compounds b) volatile compounds c) Salts d) b&c 15-Which of the following methods is often referred to as mechanical separation processes. a)-Gas Chromatography b)-column chromatography c)- Sedimentation 16- For obtaining better resolution in TLC. and then developed with a second solvent at right angles to the first a) Stepwise b) Descending e) Ascending 17- This is defined as transport of electrically charged particles in a direct-current electric field a) ion exchange chromatography b) Electrophoresis c) ultracentrifuge d) exclusion 18-This figure indicates to schematic Diagram of a) Gas chromatography…

19. What is thin layer chromatography (TLC) LEAST useful for from the list below? A) To determine if crystallization or distillation may be more effective for a separation B) To determine the number of components in a mixture C) To determine the appropriate solvent for column- chromatographic separation D) To monitor the progress of an organic synthesis reaction 14. The solubility of salicylic acid in water is 7.8g/100ml at 100°C and 0.25g/100ml at 25°. Estimate how much water is needed to recrystallize a 19g sample of salicylic acid? A) 150ml B) 250ml C) 300ml D) 400ml

A young researcher set out to develop a method for quantifying the polycyclic aromatic hydrocarbon (PAH) content in a contaminated soil sample using open tubular gas chromatography. During the initial stages of method development, the researcher was unable to separate the early eluting compounds, anthracene and naphthalene, with baseline resolution. Select the possible modifications the researcher could make to improve the resolution. use a column with a smaller inner diameter decrease the column length increase the stationary phase thickness increase the temperature choose a different stationary phase

Look up the boiling point for each of the following compounds then determine the order that they will elute from the column. Use this elution order to identify the compound in each of the 6 standard chromatograms. Once you have identified the compound in each chromatogram, record its retention time. Compound Structure Compound Name Elution Order (1-6) Non polar → Polar Boiling Retention Time (From Chromatograms) Point Propyl acetate H H. H. Butyl acetate H. H. H H. H H. H. H. Methanol H O- Ethanol 2-butanone H H H. H. 4-methyl-2- pentanone H. H. HH H.

Three students did a chromatography experiment, where Rf = distance of solute / distance of solvent. What could be the possible errors why student 3 had results that are quite far from that of students A and B?

use the following chromatogram and table as your data.       What is the %composition of the Vitamin A peak in the sample?     78.43%        77.73%     7.867%       72.74%

Q1: The following are relative peak areas for chromatograms of standard solutions of methyl vinyl ketone (MVK) MVK concentration mmol/L 0.5 Relative peak area 3.76 1.5 9.16 2.5 15.03 3.5 20.42 4.5 25.33 5.5 31.97 A sample containing MVK yielded relative peak area of 21.3. Calculate the concentration of MVK in the sample.(use excel)

1a) Hexane, CH3(CH2)4CH3, is found to have a long retention time when separated from a mixture. A column with a C18 (18-carbon chain) stationary phase and a methanol-water modal phase is used for the separation. Explain why hexane has a long retention time. 1b)You wish to chromatographically seperate a mixtureof the follwing compunds. Which of the two compounds will be most difficult to seperatate from one another? Why?

The uses of thin layer chromatography are: 1) To identify unknown compounds 2) Determine purity of products 3) Analyze reaction mixtures 4) To waste time in lab 5) Determine the melting point of the product U 6) Put an astronaut on the moon.