Recrystallization in the case of two solvents

  • Thread starter leah3000
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In summary, to recrystallize a compound that is very soluble in solvent A at room temperature and sparingly soluble in solvent B at the boiling point of B, one would add 1g of the compound to a conical flask and heat it with 4ml of solvent B just below its boiling point. Then, solvent A would be added until the compound is barely dissolved. The solution would be allowed to cool slowly, and the crystals would be filtered using a Buchner funnel and aspirator. The resulting crystals would then be rinsed with cold solvent B to prevent them from dissolving again, since the compound is very soluble in solvent A.
  • #1
leah3000
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Homework Statement



In point form briefly explain how you would go about recrystallizing a compound very soluble in solvent A at room temperature and sparingly soluble in solven B at the bp of B.




The Attempt at a Solution


-Add 1g of compound to a conical flask
-Add 4ml of solvent B to the conical flask and heat to just below bp
-To this, add solvent A until compound is barely dissolved.
-Allow the solution to cool slowly in order for the crystals to grow and filter using Buchner funnel and aspirator.
-Rinse crystals using cold solvent B.

I used solvent B first because generally the compund should be sparingly soluble in the solvent at room temp and the compound is very soluble in A.

I rinsed the crystals in cold solvent B so as to not dissolve the crystals again as the compound is very soluble in A

Is this correct?
 
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  • #2
can anyone help me with this?
 

1. What is recrystallization in the case of two solvents?

Recrystallization is a process in which a solid substance is dissolved in a solvent and then slowly cooled in order to form well-defined crystals. In the case of two solvents, this process involves using a mixture of two solvents to dissolve the substance and then slowly cooling the solution to promote crystal growth.

2. How does using two solvents in recrystallization differ from using one solvent?

Using two solvents in recrystallization allows for better control over the solubility and crystallization process. This is because different solvents have different properties, such as polarity and boiling points, which can be adjusted to optimize the conditions for crystal formation. This results in purer and more well-defined crystals compared to using just one solvent.

3. What are the advantages of using two solvents in recrystallization?

The main advantage of using two solvents in recrystallization is the ability to obtain purer and more well-defined crystals. Additionally, using two solvents can also help to reduce the amount of solvent needed and shorten the recrystallization process. This method is also useful for substances that are difficult to dissolve in a single solvent.

4. What factors should be considered when selecting two solvents for recrystallization?

The two main factors to consider when selecting solvents for recrystallization are their relative polarities and boiling points. It is important that the solvents have different polarities to maximize the difference in solubility between the hot and cold solutions. The boiling points of the solvents should also be significantly different to facilitate easy separation of the solvents after recrystallization.

5. Are there any safety precautions to keep in mind when using two solvents in recrystallization?

Yes, there are several safety precautions to keep in mind when using two solvents in recrystallization. It is important to work in a well-ventilated area and avoid inhaling the fumes of the solvents. Additionally, some solvents may be flammable or toxic, so proper protective gear should be worn and handling procedures should be followed carefully to avoid accidents.

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