Which statements are FALSE about selecting a solvent for recrystallization?
(Select all correct answers.)
Any solvent can be used for recrystallization as long as the compound dissolves in it.
The compound should exhibit a high solubility in the solvent at high temperature.
The compound should exhibit a fairly high solubility in the solvent at low temperature.
The compound should dissolve better in the chosen solvent than the impurity at low temperature.
The compound should exhibit a relatively steep solubility curve in the chosen solvent.
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To determine which statements are FALSE about selecting a solvent for recrystallization, let's evaluate each statement one by one:
1. Any solvent can be used for recrystallization as long as the compound dissolves in it.
This statement is FALSE. Not every solvent can be used for recrystallization. The solvent should be carefully chosen based on its ability to dissolve the compound of interest while minimizing the solubility of impurities.
2. The compound should exhibit a high solubility in the solvent at high temperature.
This statement is TRUE. The compound should have a high solubility in the solvent at high temperature, as this helps dissolve the compound completely during the recrystallization process. Solubility decreases as the temperature decreases, leading to crystallization of the compound.
3. The compound should exhibit a fairly high solubility in the solvent at low temperature.
This statement is FALSE. The compound should have a low solubility in the solvent at low temperature to promote crystallization. By cooling the solution, the compound will become less soluble, allowing it to form crystals while leaving impurities in the solution.
4. The compound should dissolve better in the chosen solvent than the impurity at low temperature.
This statement is TRUE. To ensure effective purification through recrystallization, the compound should dissolve better in the chosen solvent at low temperature than any impurities present. This ensures that the impurities remain in the solution while the compound crystallizes.
5. The compound should exhibit a relatively steep solubility curve in the chosen solvent.
This statement is TRUE. For a successful recrystallization process, the compound's solubility in the chosen solvent should have a steep solubility curve. This means that even slight temperature changes will cause significant changes in solubility, aiding the crystallization process.
In summary, the FALSE statements about selecting a solvent for recrystallization are:
- Any solvent can be used for recrystallization as long as the compound dissolves in it.
- The compound should exhibit a fairly high solubility in the solvent at low temperature.