What's In a Mixture - Thin Layer Chromatography - Whats in a Mixture Thin Layer Chromatography Pre-lab assignment Name This assignment must be completed

What's In a Mixture - Thin Layer Chromatography - Whats in...

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What’s in a Mixture? Thin Layer Chromatography Pre-lab assignment Name: This assignment must be completed on these sheets and submitted to the Tutor at the start of the Laboratory session in which you will carry out the associated experiment. Planning Sketch a table which will allow you to record all three measurements and the R f values for each plate, in each different solvent, or combination of solvents. Headings for columns and rows should be included. For convenience, please enter the list of solvents in the first column, in alphabetical order and with single solvents placed before binary solvents. The table should be complete (part of the aim of this exercise is to get you to anticipate the number of different solvents in which you will need to carry out elutions). Practical points a) Draw a labelled diagram showing a cross-section through the TLC plate which you are going to use. b) Draw the structures of: phenol: hydroquinone:
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c)Why is diethyl etherused as a solvent for phenol and hydroquinone in the plate-spottingprocedure?d)This diagram of a TLC plate in a TLC tank is incorrect. Draw a corrected version next to it.e)What should be your first action after removing an eluted plate from the TLC tank?Health and Safetya)State the exposure limit (mg m-3), hazards and waste disposal methods for the followingcompounds used in this Experiment:Substances to be usedQuantityExposurelimit* /mg m-3HazardsWaste disposalphenolapprox.50 ghydroquinoneapprox.50 g* Long term exposure limit (8 hour TWA reference period)b)Complete the following statements about the control measures to be used in this Experiment,and then copy your answers into the appropriate spaces in the Instructions for thisExperiment.1.General:
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Deal with spills by ........................................................................................................ 3. Iodine : Use only in a .......................................................
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Synopsis Background Thin layer chromatography (TLC) is a widely used technique for qualitative analysis of organic substances. It is a very sensitive method, requiring extremely small amounts of compound. The technique involves passage of a solution of the substance under study through a solid stationary phase; so it is a form of liquid-solid chromatography . By running standards on the same TLC plate it is possible to compare an unknown compound with the standards. However, like all chromatographic methods, TLC can prove that compounds are different, but it cannot prove conclusively that two substances are the same. Separation of compounds on a TLC plate is based on their differing degrees of adsorption by the stationary phase. Detection of compounds after separation can be by a variety of techniques, both destructive and non-destructive. Your introduction to TLC in this experiment takes you through the stages of preparing a TLC tank and TLC plates, “running” the TLC plates, and assessing the results. Carrying out a series of “runs”, you will be able to determine the best solvent, or combination of solvents, to separate the components of a mixture of phenol and hydroquinone (1,4-dihydroxybenzene).
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