answer the following questions regarding an extraction lab In general, the reaso
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answer the following questions regarding an extraction lab
In general, the reasons why an organic solvent is chosen for an extraction. The proper operation of a separatory funnel before, during, after extraction. The reason why your drying agent was added to your organic layer, even though the aqueous layer was previously removed. Evaluate the statement: "The purpose of the rotary evaporator is to dry the sample" Name the 2 physical process occurring inside the rotavap. Describe the side effect of rotavapping that makes it necessary to place a warm water bath underneath. Name the reason for this side effect, using thermochemistry. The reasons why urea is insoluble in MTBE. Use ChemDraw structures in your explanation. The reasons why urea and acetanilide, which have similar structures, can have different solubilities in MTBE. Be as specific as possible. The reason why acetylsalicylic acid was able to be extracted to the aqueous layer and then precipitated out of the aqueous layer. Be as specific as possible. Present a flowchart that starts with your original mixture, and branches to eventually separate out each component in the mixture. Be detailed!Explanation / Answer
1) the reasons why an organic solvent is chosen for an extraction
For an organic compound, it is relatively safe to assume that it will dissolve better in the organic layer than in most aqueous solutions unless it has been converted to an ionic species, which makes it more
water-soluble.
2) The proper operation of a separatory funnel before, during, after extraction.
Before using the separatory funnel, the user should check if the stopcock plug and the stopcock fit together well. In addition, the stopper on the top has to fit into the joint on the top to prevent
leakage there. It is important to check whether there is any leakages during the process of extraction.
3) The reason why your drying agen was added to your organic layer, even though the aqueous layer was previously removed.
Because, the organic layer still contains some ammount of water, which can be removed by addition of drying agents such as MgSO4 or Na2SO4.
4) The purpose of the rotary evaporator is to dry the sample.
Since the flask is rotated during the evaporation process, the surface area is larger than normal which increases the evaporation rate significantly. The solvent is collected in a flask and can properly
be disposed off afterwards (organic solvent waste). In addition, this method also avoids overheating of the target compound i.e. oxidation because lower temperatures are used. The same rules like for vacuum
filtrations apply here in terms of the glassware and other precautions i.e no cracks on the flask, etc.
5)Name the 2 physical process occuring inside the rotavap.
the boiling points of liquids reduces on decreasing their pressure, allowing solvents to be vaporized at much lower temperatures than their boiling points at normal pressure.
A condenser at the other end converts the gas back to liquid, which requires lowered temperatures. Liquid nitrogen, dry ice or water is used in achieving the cooling effect, after which the condensed
liquid is collected in a separate vessel.
The evaporation vessel constantly rotates. This tactic aims to increase the surface area of the liquids. The centrifugal force keeps the liquid sticking to the inner surface of the vessel, exposing a larger surface area and causing faster evaporation.
6. Decribe the side effect of rotavapping that makes it necessary to place a warm water bath underneath.
Evaporation is an endothermic process, in that heat is absorbed during evaporation. So, under reduced pressures, the solvent boils at significantly lower temperature and we can observe the lowering of solvent temperature during the evaporation process. To speed up the evaporation process we use water bath.
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