Among the Following Solvents-Water, Acetone, Ethanol, and Toluene

1. Among the following solvents-water, acetone, ethanol, and toluene, which one was

observed to be most suitable for recrystallization of acetanilide? Why?

Water. Acetinilide is only soluble in hot water, not cold water.

2. Why was a water bath used instead of direct heating in the choice of solvent?

A water bath is used because many organic solvents are dangerously flammable.

3. Why was activated charcoal added into the mixture of acetanilide, sodium chloride and

congo red? What is adsorption?

Activated charcoal adsorbs the impurities. Adsorption is the accumulation of gases, liquids, or solutes on the surface of a solid or liquid.

4. Would it be wrong to dissolve the original impure material in a large excess of solvent?

Why?

Yes, because crystals will not form in a large excess of solvent.

5. In gravity filtration, what is the advantage of using a short-stemmed funnel over a long-stem

funnel?

A short stemmed funnel must be used in gravity filtration so that the prosses is quicker and nothing cools in the stem.

6. Why were the funnel and the flask preheated before filtering the impure acetanilide?

The funnel and the flask must be preheated so that all of the solution will have passed through and no crystals will be formed in the funnel.

7. Why was the filter paper in the Büchner funnel moistened before pouring in the mixture

containing the acetanilide to be recrystallized?

The filter paper must be moistened so that it adheres properly in the funnel.

8. What is the purpose of washing the acetanilide crystals with a few mL of cold solvent? What

do you think would happen if the washing solvent was not cold?

Cold solvent must be used in order to dissolve the impurities. If the solvent used was not cold, the product would be dissolved too.

9. Why must the rubber tubing of the suction flask be disconnected before turning off the water

aspirator?

The rubber tubing must be disconnected first because if you turn off the aspiratior first, suck-back into the aspirator would occur.

10. Why is it necessary to use thick-walled tubing

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