In the solvent pair experiment for recrystallization, why is there no concern for vigorous boiling when adding a second solvent?

The option indicating that the procedure ensures control of boiling point is correct because, in recrystallization, careful management of temperature is crucial for achieving effective solubility and crystallization. When adding a second solvent to a boiling solution, maintaining control over the boiling point helps to avoid sudden boiling or bumping that can lead to loss of material or dangerous splattering.

Typically, the goal of adding a second solvent is to create a mixture with a more desirable solubility profile for the solid being recrystallized. By incrementally adding the colder solvent while still managing the first solvent's temperature, chemists can ensure that the solution remains at a level conducive to dissolving the solute without causing violent boiling. This aspect of the procedure is vital for ensuring that the dissolved components can re-form as pure crystals once cooled without introducing the risk associated with vigorous boiling or unsafe reactions.