23.1.10 CIA Demonstration: Recrystallization

Question 1

CIA Demonstration: Recrystallization

Answer 1

• Recrystallization can be used to purify a compound from a solution with impurities.

Question 2

note

Answer 2

• Five grams of acetylsalicylic acid are added to a beaker containing a small amount of water, and water at 100 ̊C is added until the solid just dissolves completely. The acetylsalicylic acid is at its saturation point.
• Blue food coloring is added to act as an impurity. The
  resulting solution is an impure saturated solution of
  acetylsalicylic acid.
• The saturation point is a function of temperature. The solution is saturated at 100 ̊C, but as the solution cools, acetylsalicylic acid will begin to crystallize out of solution.
• When the solution is cooled and the acetylsalicylic acid has recrystallized, the solid crystals are collected using vacuum filtration. After rinsing with cold water, the crystals are clear—the impurity (blue food coloring) has been removed.