In a preliminary experiment, a solution containing 0.0837 mg benzene and 0.0666 mg toluene was analyzed by gas chromatography and gave peak areas of 495 for benzene and 367 for toluene.  After this, the amount of unknown was determined by adding 0.0561 mg of benzene to a solution containing an unknown amount of toluene.  The peak areas determined for benzene and toluene in this analysis were 643 and 515 respectably.  How many mg of toluene are present in the sample?

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Below are the gas chromatography results of two separate distillations of the same 1:1 mixture of ethanol and 1-butanol. One sample was obtained from the first fraction of a simple distillation and one sample was obtained from the first fraction of a fractional distillation. Identify the peaks in the chromatographs.  Discuss the conclusions you can make regarding simple distillation compared with fractional distillation.  Which method was more successful?

Iman has a mixture of two compounds A and B. A is a protein, and B is a lipid. He plans to separate the mixture using a column chromatography technique. He packed the column with amino bonded with siloxane material and use a mixture of 20:80 of water: hexane as the mobile phase. i) Sketch the apparatus set up for the chromatographic technique used by Iman. Use the correct chromatographic terminologies to label all of the apparatus, materials, and phases. ii) Predict the sequence of elution when the mixture was loaded onto the separation column. Justify your answer. iii) After the first compound was eluted, Iman discovered that the second compound was taking too long to pass through the column. Please suggest any strategies that could be used to aid the elution process.

A student researcher performed a chromatographic separation of caffeine and aspartame. The retention time for caffeine, tc, was found to be 209.6 s with a baseline peak width, w., of 14.4 s. The retention time for aspartame, ta, was 260.0 s with a baseline peak width, wa, of 21.2 s. The retention time for the unretained solvent methanol was 49.2 s. Calculate the average plate height, H, in micrometers for this separation, given that it was performed on a 22.1 cm long column. H = um %3D Calculate the resolution, R, for this separation using the widths of the peaks. R = Calculate the resolution if the number of theoretical plates were to increase by a factor of 2. R2N =

6.0 mL of cyclohexanol, 8 mL of 85% phosphoric acid, and 10 drops of sulfuric acid are added to a 50-mL round-bottom flask with boiling chips, and the mixture is distilled into an ice-cooled receiver. The distillate is in the form of a colorless bi-phasic mixture. The cyclohexene upper layer is removed from the water layer, and dried over anhydrous calcium chloride. Isolated is cyclohexene as a clear and colorless foul-smelling liquid. Weighing data is given below. Gross mass: 51.24 g Tare mass: 48.04 g Product mass: 3.2g Question:  Calculate the theoretical mass of the cyclohexene product, bearing in mind that the cyclohexanol starting material was measured by volume, not by mass (so you must use the density of cyclohexanol to convert milliliters to grams, before calculating the number of moles). Calculate the percent yield of cyclohexene obtained.

Fractional distillation of a mixture of two compounds gives the following data after the GC analysis and peak integration: Peak 1 (corresponding to compound 1), area = 70.3 sq units Peak 2 (corresponding to compound 2), area 28.7 sq units What was the original percentage composition of the two compounds in the mixture? O Compound 1 29.0% Compound 2 = 71.0% Compound 1=71.0% Compound 2 = 29.0% Compound 1 = 41.0% Compound 2 = 59.0% Compound 1 =61.5% Compound 2 = 38.5%

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?

2 Suppose a particular extraction proceeds with a distribution coefficient of 7.5. The mixture consists of a certain amount of caffeine dissolved 100 mL of water a. How much caffeine was originally used when 0.31 g of the organic compound was dissolved in water and 150 mL ether was used as extraction solvent b. How much was dissolved in ether?

Sketch a chromatogram for a compound with a stronger interaction with the stationary phase than the one shown below (draw on top of the shown chromatogram). Briefly explain how and why it is different.