Purpose: To distill aqueous solutions of sodium hydroxide and potassium permanganate, and compare the properties of the solution before distillation with the distillate.

Vocabulary
filtrate - the liquid that has passed through filter paper.
distillate - the liquid evaporated, condensed, and collected after distillation, also sometimes called "condensate."
residue - the material that remains behind after filtration or distillation.

Litmus paper comes in several forms. We will use red and blue litmus paper to test whether our solutions are acidic or basic.  In a basic solution, both kinds of litmus paper end up blue.  In an acidic solution, both will end up pink.  If neither changes color, the solution is neutral.

CAUTION:

• Sodium hydroxide (NaOH) is very caustic.  DO NOT touch the pellets.
• Potassium permanganate (KMnO4) is a strong oxidizer.  DO NOT let it touch anything flammable such as clothes, plastic, rubber or cork stoppers, skin, etc.
• Wear goggles at all times and follow all safety rules.

Part 1

1. Set up the distillation apparatus as shown.
2. Test distilled water with red and blue litmus paper, and record your results.
3. Prepare an aqueous solution of sodium hydroxide by dissolving a few pellets of sodium hydroxide in about 70 mL of distilled water.
4. Test the solution with red and blue litmus paper and record the results.
5. Pour the water through a small piece of filter paper.  Test the filtrate with red and blue litmus paper and record the results.
6. Distill the solution.  Do not let the flask dry out over the flame. Record the constant temperature of boiling.
7. Test the distillate with litmus paper and record the results.
8. Clean the flasks and go on to part 2.

1. Prepare an aqueous solution of potassium permanganate by dissolving one crystal of potassium permanganate in about 70 mL of distilled water.
2. Record your observations about the color.
3. Filter the solution, and record the color of the filtrate.
4. Distill the solution.  Do not let the flask dry out over the flame. Record the constant temperature of boiling.
5. Record your observations about the color of the distillate.
6. Clean the glassware carefully and allow it to air dry.

                    distillation apparatus

Note
If time does not permit carrying out both parts of this activity, your instructor may suggest using phenolphthalein indicator in part 1, instead of testing with litmus paper.  Phenolphthalein turns pink in basic solutions; otherwise it is colorless.

[Distillation score sheet][MHS Chem page]