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Safari File Edit View History Bookmarks Window Help a 27% G) Fri 3:15 PM mycourses.purdue.edu CALCULATIONS: percent recovery of each component from initial mass PRE-LAB QUESTIONS In a separation experiment using an aqueous solution and dichloromethane, which layer is on the bottom of the separatory funnel-the aqueous layer or the dichloromethane layer? What physical property allows you to determine this without doing the experiment in lab? Describe an experimental procedure that you could use to test whether or not a particular layer in a separatory funnel is aqueous. 1. 2. Why is acetone used to rinse the original beaker and to wash the solid compound on the Buchner funnel? In Step 5 of the Procedure section below, why are you adding calcium sulfate to the solution in the Component B flask? Write out the flow chart on p.2. Using the information in the Introduction and Procedure sections of this lab, identify the Components A B, and C, and determine what compounds should be in the boxes with question marks. Note that the answer to this question is NOT a replacement for the Procedure section of your lab report What is a partition coefficient? Why is it better to use several small washings/extractions rather than one large washing/extraction? What is the difference between an extraction and a wash? 3. 4. 5 You will be using melting point to confirm the identity of the unknown drug in your drug mixture. If you did not have melting point data, could IR spectroscopy be used to differentiate among the three possible unknown drug compounds? Explain why or why not.Explanation / Answer
1) Dichloromethane layer of the separating funnel will come in the bottom of the separating funnel because dichloromethane have higher density than aqueous. Density of the both materials will be useful physical property to assign the layer without doing the experiment in lab.
2) Acetone is one of the highest polar solvent which is missble with water, so to remove aqueous and soluble impurities it was used to rinse the apparatus. It can be easily evaporated becsuse of its volatile nature. Solid compound of the buchner funnel was washed with acetone to remove the soluble impurity from the solid compound.
4) The ratio of the concentrations of a solute in two immiscible or slightly miscible liquids or in solids, when it is in equilibrium across the interface between them is know n as partition coefficient. Several small washing/extraction were more effecient because in different attempts more nunmber of particles will come in contact of the solvent used for extraction and much yeild with purity will be obtained. Washing is the process to remove the impurity from solid stuff while extraction is the isolation of the required product from different liquid medium.
5) IR spectroscopy can be used to differenciate the various products in the mixture because every drug will have its own functional group with different isomeric nature and every different functional group will give separate stretching frequency. Stretching frequency is the fundamental requirement for ir characterization hence we can easily distinguish all the three different product.
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