Please help me answer this question;

Question

The goal of the recrystallization procedure is to obtain purified material with a maximized recovery. For each of the following, explain why this goal would be adversely affected.

a) In the solution step, an unnecessarily large volume of solvent is used.

b) Crystallization is accelerated by immediately placing the flask of hot solution in ice water.

Answer 1

In recrystallizations, one uses the minimum amount of solvent to dissolve the material in a HOT solution, then cools the solution to obtain the crystals. The idea is that the solute is less soluble in the cold solution than in the hot solution.
a. If one uses too much solvent, there is just that much more loss when the solution is cooled. More solvent means more of the solute will dissolve. In real practice, one can have so much solvent that ALL of the product is lost.

b. If the solution is suddenly cooled, for example with an ice bath, the solute precipitates VERY FAST and that entraps both solvent and some of the impurities into the crystal structure (not necessarily inTO the crystal structure but into the spaces (interstices) within the crystal itself). When I was in school they called this co-precipitation. In fact, a large part of my dissertation was on co-precipitation (but I wanted it). I don't know what they call it in today's world.

Answer 2

. A student performed a recrystallization of phthalic acid and used 35 mL of water as solvent.
Assuming no loss of solvent to evaporation, calculate the loss of product in the filtrate based on
the solubility of phthalic acid

Answer 3

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