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?

  • ACooling the flask
  • BEvaporation of solvent
  • CGravity filtration
  • DScratching the inside of the flask
  • EAdding a second solvent

Q2:

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

  • AThe recrystallized material is washed.
  • BThe crude material is fully dissolved.
  • CThe solution is left to cool.
  • 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?

  • AGravity filtration
  • BCooling
  • CAdding a seed crystal
  • DScratching the inside of the flask
  • EEvaporation of solvent

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

Q5:

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

  • A
  • B
  • C
  • D
  • E

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