The result of a TLC experiment showed that a compound has an Rf value of 0.25 on a silica gel plate using 10% ethyl acetate in hexane as the mobile phase. Indicate if the Rf values of the compound would be higher or lower in each of the following solvents. Breifly explain your reasoning for full credit: (a) 100% hexane (b) 100% Toluene (c) 50:50 of hexane ethyl acetate (d ) 95:5 of ethyl acetate: methanol

What is the order in which the following compounds would he eluted from an HPLC column containing a reversed -phase packing?(a) benzene, diethyl ether, n-hexane(b) acetone, dichloroethane, acetamide

2. Thin layer chromatography was performed to find the most effective mobile phase needed to separate a mixture containing three compounds (using silica gel as the stationary phase). TLC analyses were performed using five different mobile phases: (A) pure petroleum ether; (B) 25:75 ethyl acetate:petroleum ether; (c) 50:50 ethyl acetate:petroleum ether (D) 75:25 ethyl acetate:petroleum ether; and (E) pure ethyl acetate. Using the TLC results provided, indicate whether an effective separation was achieved for each of the five mobile phases. Be sure to provide a brief explanation for your answer and identify which mobile phase(s) could be used to offer an effective separation of this mixture using column chromatography. A D E

From the study with UV-Vis spectroscopy, four samples of solutions with different known concentrations of atrazine were analyzed, using a 1 cm optical path cuvette at 220 nm. The analytical curve (calibration curve) with absorbance values ​​(y-axis) per atrazine concentration (x-axis) provided a straight line with the following parameters: linear coefficient = 0 and slope = 760. assumptions of the Lambert-Beer Law, evaluate the following statements: I. The molar absorptivity coefficient (E), under the described experimental conditions, cannot be determined. II. A sample of a solution containing atrazine with an absorbance of 0.2 will show a concentration of 2.6x10-4 mol/L. III. Atrazine concentrations could be determined due to absorption taking place in the visible region. IV. The change in absorbance as a function of the analyte concentration is directly related to the absorptivity coefficient of atrazine and the length of the optical path of the cuvette. It is correct only what is…

What is the relationship between elation volume and molecular weight of the elute?

Please give me correct solution.

Predict the order of elution for the silica gel adsorption TLC separation of the mixture containing aspirin, acetaminophen and caffeine using methylene chloride solvent. Explain.

Explain why TLC cannot be used for some volatile low molecular weight substances such as toluene.

Write the principles of the following methods:(i) Vapour phase refining(ii) Zone refining(iii) Chromatography

This is a ATR spectrum. In which caffeine/PVA films were measured. Line a) correspond to a pure pva film and the other lines are films at increasing caffeine concentration. Notice that the OH band at around 3200cm-1 decreases at higher caffeine concentrations. However at a certain concentration (line d) such band starts to increase back to the initial intensity. What does that mean? Waht is the chemical meaning for that behavior?