help please 3. You have been given the task of purifying a 60 mL sample of tolue

Question

help please

3. You have been given the task of purifying a 60 mL sample of toluene. In order to develop your plan of action, you ask about the impurities likely to be present in the sample. You are told that it contains small amounts of acetone (~10%).

a Which technique would you choose for the purification process? Why? (1 point)

b. Clearly describe the procedure you would use. (3 points)

c. What simple chemical test, performed with the original sample and the purified product, will help you confirm that the acetone impurity has been removed during the purification process? (1 point)

Explanation / Answer

The easiest way to dry the collected crystals is to be patient and allow nature to take its course. Leave the crystals in a container open to the air in your desk. Over a period of a few days, depending on the boiling point of the solvent, they will dry. If there is not sufficient time to allow this slow drying process or if you are using test tubes, reaction tubes or solvents with higher boiling points, such as toluene or water, there are several other methods including vacuum drying or using a stream of nitrogen. Pressing the solid between pieces of filter paper or paper towel is a simple way to remove a major proportion of a solvent. Vacuum drying can be easily accomplished with the desk equipment provided. If your product is in a reaction tube from a pipet filtration, you can connect the yellow thermometer adapter to the reaction tube and then on to a piece of thick-walled rubber tubing using the cut off barrel from a 1-mL plastic syringe. Connect the tubing to the house vacuum and allow it to dry. (Figure 4.7) Alternatively, the reaction tube can be pushed directly into the opening of the thick-walled tubing. Eveaporation is speeded up by clamping the reaction tube in a beaker of warm water. This method should only be used to dry residual solvent. Using a vacuum to remove large amounts of solvent will be slow and could eventually destroy the vacuum pumps.

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