Experiment 9_ Column Chromatography

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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

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.

Which statement is true? Statement 1: In Thin Layer Chromatography (TLC), the polar compounds will have a greater Rf value compared to that of non-polar compounds.Statement 2: The stationary phase in TLC is polar.

Chemistry Briefly describe the differences between the scanning and SIM approaches with reference to your data. Discuss how and why your scanning (TIC) and SIM (mass chromatograms look different. Pay particular attention to selectivity of compounds detected and signal-to-noise. What are some advantages of SIM? What are some disadvantages?

1. How does chromatography separate the components of leave samples? 2. Can you use chromatography to purify a mixture? why? 3. What is Rf value and its significance in chromatography?

Identify the detectors in gas chromatography that can be used for the detection of each type of analyte. More than one detector may be appropriate for a given analyte, and a given detector may be appropriate for more than one type of analyte. compounds ionized by UV radiation sulfur or nitrogen containing compounds halogenated compounds flame ionization Answer Bank mass spectrometer nitrogen and phosphorous containing compounds thermal conductivity electrolytic conductivity hydrocarbons electron capture thermionic photoionization

The paper used in chromatography is made of molecules with___parts A polar  B nonpolar

4) If the classification of the chromatography run is a reverse-phase chromatography, discuss the relative polarities of caffeine, aspartame and benzoate

Why chromatography is an important tool for analysis of organic compounds?

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Explain the following Chromatography (for drug analysis) Thin-layer chromatography (TLC) Gas chromatography (GC) Liquid chromatography (LC) (i.e, high performance liquid chromatography or HPLC)

1. In thin layer chromatography (TLC), explain how the pigments separate on a piece of paper. 2. If the spots are colorless on a TLC plate, how can you make it visible? Enumerate 2 ways and discuss each.

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?

Question: Can thin-layer chromatography (TLC) be used to differentiate between two closely related compounds with similar structures?

Match the following types of column chromatography with the underlying principle. Affinity chromatography HPLC lon-exchange chromatography (IEX) Size-exclusion chromatography ✓[Choose ] exploits differences in molecular size of individual proteins exploits differences in the size and magnitude of the net charge of individual proteins at specific pris requires a ligand (specific binding partner) to attract and retain a target protein relies on high pressure pumps that force proteins through a column [Choose] [Choose ]

Chromatography (DRUG TEST) Thin-layer chromatography (TLC) Gas chromatography (GC) Liquid chromatography (LC) (i.e, high performance liquid chromatography or HPLC)

4) If the classification of the chromatography run is a reverse-phase chromatography, discuss the relative polarities of caffeine, aspartame and benzoate.

An example of planar chromatography is:   Column chromatography    HPLC   GLC   TLC

Which statement is true? Statement 1: In a paper chromatography that uses a cellulose-based filter paper as stationary phase and hexane as the mobile phase, polar compounds are expected to have higher Rf values than that of non-polar compounds.Statement 2: In paper chromatography, polar compounds tend to outdistance the non-polar substances.

The following sentence has the format “Statement 1 BECAUSE Statement 2”. Decide whether statement 1 is true, whether statement 2 is true, and whether the REASONING (the ‘BECAUSE’ relationship) between them is valid. Statement 1 − “Cyclohexane-1,2-diol elutes from a silica gel chromatography column after cyclohexane-1,2-dione” BECAUSE Statement 2 − “Ketones stick better to silica than alcohols because the C=O group has a larger dipole than the C-OH group.”   Question 6 options: A Statement 1 and Statement 2 are both correct, and the reasoning is valid.  B Statement 1 and Statement 2 are both correct, but the reasoning is NOT valid. C Statement 1 is correct, but Statement 2 is NOT correct.   D Statement 1 is NOT correct, but Statement 2 is correct. E Statement 1 and Statement 2 are both NOT correct

Which of the following chromatographic methods cannot use a mixture of liquid solvents (eluents) during the separation process?     Thin layer chromatography     High pressure liquid chromatography     Column chromatography     Gas chromatography

2. Consider the following example GC Chromatogram from a publication about aggression among Mediterranean Acrobat Ants (C. scutellaris). This particular sample was generated by rinsing hydrocarbons from ant exoskeletons. From the chromatogram, what is the minimum number of unique compunds present in the sample? What data led you to that conclusion? (Don't overthink it) 2 8000000 7000000 6000000 5000000 4000000 3000000 2000000 1000000 Counts (Abundance) 5 19 6 7 0 23.00 24.00 10 | 11 13 17 20 14 15 16 12 teel | 22 19 21 ли 25.00 26.00 27.00 Time "Example of a Gas chromatography-Mass spectrography (GS-MS) chromatogram of hydrocarbon molecules in C. scutellaris" by Filippo Frizzi, et.al, in PLoS One is licensed under CC BY 4.0

Dissolve 1 mL of clove oil in 2 mL of dichloromethane. Add 10 mL of aqueous sodium hydroxide (NaOH) solution. Shake and separate layers, keeping the organic layer (dichloromethane). Obtain a silica-packed chromatography column. Add 2 mL of hexane to the column, allow the solvent to just reach the top of the silica packing, then immediately add the dichloromethane layer that was separated earlier. Allow the organic layer to just reach the top of the silica packing, then immediately add 10 mL more of hexane. When the solvent just reaches the top of the silica packing, switch solvents by adding 10 mL of acetone. Switch to acetone. a) Which component of clove oil (eugenol, eugenyl acetate, or caryophyllene) ends up in the layer containing the NaOH? Explain your answer. b) Which component of clove oil (eugenol, eugenyl acetate, or caryophyllene) is pushed down the column by hexane, a non-polar solvent? Explain your answer. c) Which component of clove oil (eugenol, eugenyl acetate, or…

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