Instructor's Notes

  1. Background Information

    See Background Information (Section II) in Lab Documentation.

  2. Lab Preparation and Equipment
    • 6-inch side-arm test tubes, at least 3 / person (see Tips)
    • Tygon tubing, 12 inches / person
    • Glass tubing (0.6 cm external diameter), 15 inches / person
    • No.2 rubber stoppers with bored holes to accommodate glass tubing, 3 / person
    • Sulfur, powder (100 mesh, Aldrich catalog no. 21, 522-6)
    • Distilled water
    • pH paper
    • Bunsen burners, 1 / person
    • Ground calcite (particle size no smaller than 1 mm)
    • CaCO3, powder (Aldrich catalog no. 239 216)
    • Magnetic spin vains, 1 / person
    • Hot plate with stirring mechanism, 1 / person
    • CaSO4 (drierite)
    • CaSO4, powder (~0.5 g / person)
    • 1M Na2CO3 solution
    • KOH, pellets (Aldrich catalog no. 22, 147-3)
    • 1M KOH solution
    • Iron ring stands and clamps
  3. Tips
    • Inserting the glass tubing through the bored holes of rubber stoppers can be difficult and there is a chance that the glass could break while doing so. To avoid injury, students should be advised to do this using a towel to hold / push the glass tubing through the stopper as opposed to using their bare hands. The use of glycerin, mineral oil, or a little bit of water in the hole and on the tubing can make this task easier. An alternative is to have the glass / stopper assembly provided by the instructor.
    • While only three side arm test tubes per person is absolutely necessary, it is recommended that a new, clean test tube be used for each sample of sulfur that is burned. The other test tubes containing the scrubbing reagent and distilled water need not be replaced each time, but they should be cleaned with a little sudsy water before performing each part of the experiment to make results more accurate.
    • As indicated in the student directions, the aspirators must be turned on to maximum power as evidenced by the production of vigorous bubbles in the distilled water. It is essential to the success of the experiment that each aspirator is working properly and providing maximum suction.
  4. Safety and Hazards

    It is highly recommended that all work be carried out in a fume hood. Inhalation of dust from sulfur, calcium carbonate, and calcium sulfate should be avoided, as the dust can be potentially irritating to the upper respiratory tract. Due to the highly corrosive nature of potassium hydroxide, it should be handled with caution, and direct contact with skin and eyes should be avoided. The 1M Na2CO3 solution should also be made and handled carefully, as it is very basic. Contact of all chemicals with eyes and other mucous membranes should be avoided. Therefore, appropriate eye protection should be worn at all times.

CAS Registry Numbers

  • Sulfur: 7704-34-9
  • SO2(g): 7446-09-5
  • CaCO3: 471-34-1
  • CaSO4: 7778-18-9
  • Na2CO3: 497-19-8
  • KOH: 1310-58-3

Exploration of SO2 Scrubbers: A First Year Environmental Project