Worksheet: Crystallization

In this worksheet, we will practice describing the correct procedure for recrystallization and its use in the production of diffraction-quality crystals.

Q1:

Which of the following is not a method for increasing the crystallization rate?

  • AGravity filtration
  • BCooling the flask
  • CAdding a second solvent
  • DEvaporation of solvent
  • EScratching the inside of the flask

Q2:

When performing a recrystallization, which of the following steps is not required?

  • AThe solution is left to cool.
  • BThe crude material is fully dissolved.
  • CThe recrystallized material is washed.
  • DThe hot solution is filtered.
  • EThe unwanted solutions are disposed of safely.

Q3:

When applied to a solution, which of the following techniques could increase the purity of the resulting crystals?

  • AScratching the inside of the flask
  • BGravity filtration
  • CEvaporation of solvent
  • DAdding a seed crystal
  • ECooling

Q4:

When recrystallizing a compound, for what purpose might the side of the flask be scratched with a glass rod?

  • ATo accelerate secondary nucleation
  • BTo mix the solution
  • CTo accelerate the growth of existing crystals
  • DTo accelerate primary nucleation
  • ETo warm the solution

Q5:

Which of the following pieces of apparatus is not typically used in recrystallizations?

  • A
  • B
  • C
  • D
  • E

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