Statements describing requirements for suitable solvents for recrystallization are listed below. Sort these requirements as either true or false. The solvent should not dissolve the compound when cold. The solvent should either dissolve the impurities at all temperatures or not dissolve the impurities at all. The solvent should not dissolve the compound while hot. The solvent should chemically react with the compound. The solvent should dissolve the compound while cold. The solvent should not chemically react with the compound. The solvent should dissolve the compound while hot.

Question

Chemistry

Mayer

11 February, 02:52

Statements describing requirements for suitable solvents for recrystallization are listed below. Sort these requirements as either true or false. The solvent should not dissolve the compound when cold. The solvent should either dissolve the impurities at all temperatures or not dissolve the impurities at all. The solvent should not dissolve the compound while hot. The solvent should chemically react with the compound. The solvent should dissolve the compound while cold. The solvent should not chemically react with the compound. The solvent should dissolve the compound while hot.

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Answers (1)

Know the Answer?

Sage Dean · Answer 1

True

True

False

False

False

True

True

Explanation:

The recrystallization is a purification process, in which a solid with impurities is dissolved in a hot solvent. The substance must be soluble in the hot solvent, so the impurities can leave the solid crystal. Then, the solution is cold, until the crystals are formed again, thus, the substance can't be soluble in the cold solvent, because if so, the recrystallization will not happen. The crystals are then separated.

Let's check the statements:

The solvent should not dissolve the compound when cold.

As explained above, this is true.

The solvent should either dissolve the impurities at all temperatures or not dissolve the impurities at all.

The impurities must be separated from the crystal, so if the solvent dissolves it has higher, it should dissolve it when it's cold because if it didn't happen, the impurities will recrystallize too. If the solvent doesn't solubilize it when it is hot, so, the impurities crystal will be formed first, and when the solvent is cold it can dissolve it because the impurities can enter the crystal compound again. So, it's true.

The solvent should not dissolve the compound while hot.

As explained above, the solvent must dissolve the compound while hot, so it's false.

The solvent should chemically react with the compound.

If the solvent reacts with the compound, a new substance will be formed, and the purification will not happen. So, it's false.

The solvent should dissolve the compound while cold.

As explained above, the compound must be solid in the cold solvent, so it's false.

The solvent should not chemically react with the compound.

As explained above, this is true.

The solvent should dissolve the compound while hot.

As explained above, this is true.