A student was given an unknown mixture andwas asked to determine its composition bythin layer chromatography using silica gel as astationary phase and a 50:50 mixture of ethylacetate:petroleum ether as the mobile phase.The unknown mixture could be composed ofcompounds A-E. The student ran one TLC platecontaining compounds A-E, and a second TLCplate of their unknown mixture. Calculate theR, values for all components identified in theseTLC analyses and use this data to determine thecomposition of the unknown mixture.-+-+-+-+-+-ABCDEUnk

I used a ruler to measure the distance as shown in my monitor.Distance travelled by solvent = 5.3 cm…

Answered: A student was given an unknown mixture…

Appl Of Ms Excel In Analytical Chemistry

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ISBN:9781285686691

Author:Crouch

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Chapter4: Least-squares And Calibration Methods

Section: Chapter Questions

Problem 3P

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A method of quantitative determination of the concentration of constituentsof a sample analyzed by gas chromatography is area normalization. Thiscomplete elution of all sample constituents is required. Thearea of each peak is measured and corrected for the detector response to the diffe- renteseluatos. This correction involves dividing the area by an empiricalcorrection factorDetermined. The concen ration of the analyte is found from the ratio between itscorrected and the total corrected area of all peaks. For a chromatogram containing threerelative areas were determined as 16.4; 45,2; and 30.2, in the order ofincreased retention time. Calculate the percentage of each compound if therelative responses from the detector are 0.65, 0.73 and 0.85, respectively.
Researchers used gas chromatography to determine the % v/v methyl salicylate in rubbing alcohol [Van Atta, R. E.; Van Atta, R. L. J. Chem. Educ. 1980, 57, 230-231]. A set of standard additions was prepared by transferring 20.00 mL of rubbing alcohol to separate 25 - mL volumetric flasks and pipeting 0.00 mL, 0.20 mL, and 0.50 mL of methyl salicylate to the flasks. All three flasks were diluted to volume using isopropanol. Analysis of the three samples gave peak heights for methyl salicylate of 57.00 mm, 88.5 mm, and 132.5 mm, respectively. Determine the % v/v methyl salicylate in the rubbing alcohol.
hree components in a mixture have varying distribution constants between the mobile phase and the stationary phass One of the components has a very low distribution constant, Would this component likely elute first or last and how would you design an experiment or modify the components of the separation to make it perform in the opposite manner?
1. The following data are for a liquid chromatographic column: length of packing: 24.7 cm VM : 1.37 mL Flow rate: 0.313 mL /min Vs: 0.164 ml A chromatogram of a mixture of species A, B, C, and D provided the following data: Retention time, min 3.1 5.4 Width of Peak Base (W), min Nonretained 13.3 14.1 21.6 0.41 1.07 1.16 1.72 Calculate: (a) the number of plates from each peak. (b) the mean and standard deviation for N. (c) the plate height for the column. (d) the capacity factor for A, B, C, and D. (e) the resolution for species B and C. (f) the length of column necessary to separate species C and D with a resolution of 1.5. ABCD
1. Calculate the difference in retention volumes for solutes A and B that are passed through a column containing 1.8 mL of stationary phase and 2.7 mL of mobile phase. The distribution coefficients of A and B are 8.5 and 16.8 respetcively.
The following data are for a liquid chromatographic column: column length 24.7 cm volume of the mobile phase, Vm 1.37 mL volume of the stationery phase, Vs 0.164 mL A chromatogram of a mixture of species A, B, C and D provided the following data: Calculate the plate height in milimeters (mm) for species A. Retention Widht of Peak Time, min Base (W), min Nonretained 3.1 - A 5.4 0.41 B 13.3 1.07 14.1 1.16 D 21.6 1.72
Which solvent mixture is best for TLC chromatography of syn- and azobenzene: 75:25 DCM: Hexanes 25:75 Hexane: Acetone 90:20 Hexanes: Ethanol
Louie performed paper chromatography to identify which among the four availablereference mixtures — WAR, OFF, YIN, MEW — have the same components as hisunknown sample, GUN. He spotted the standards and the sample in a Whatman No. 1filter paper, which he placed in a developing chamber containing 3% KCl. After 20minutes, Louie obtained the chromatogram below, immediately noting that the distancetravelled by the solvent from the origin is 79.0 mm. On the other hand, the distances (incm) traveled by the developed spots were tabulated as follows.(see attached) Questions: 1. Is the type of paper chromatography performed normal or reversed? Why?2. Calculate the Rf of the spots from the samples. Report your answers in four decimal places.
I) Sketch the apparatus set up for the chromatographic technique used byIman. Use the correct chromatographic terminologies to label all of theapparatus, materials, and phases. II)Predict the sequence of elution when the mixture was loaded onto theseparation column. Justify your answer. III) After the first compound was eluted, Iman discovered that the secondcompound was taking too long to pass through the column. Please suggestany strategies that could be used to aid the elution process. Justify youranswer.
true or false: You are using an HPLC method based on partition chromatography to separate four analytes. Each analyte has the same equilibrium constant value that describes its interaction and concentration in the stationary and mobile phases.
The required mobile phase for the analysis caffeine in soft drinks in liquid chromatography are methanol and water. What class of methanol and water must be used? Kindly explain the answer.
Next, 2.00 mL of 9.63 mM S was added to 10.00 mL of a solution of unknown concentration of X, and the mixture was diluted to 25.0mL. Chromatographic analysis of this solution produced peak areas of 4822 for X and 4099 for S. What was the concentration of 5 (in mM) of the 25.0mL solution?

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