1. Assemble a gas collecting apparatus for collecting a gas by water displacement. Your facilitator will provide help, when needed.
2. Fill 5 bottles to the brim with water and cover each with a glass square.
3. Invert the first bottle into the trough. The others will be inverted into the trough as needed.
4. Pour approximately 200 ml of 3% H₂O₂ into the gas generator.
5. Position the free end of the rubber hose under the mouth of the inverted bottle in the trough.
6. Using a spatula, add a tiny amount of MnO₂ into the gas generator and replace the stopper at once.
7. Oxygen will begin to be collected in the inverted bottle by displacement of the water in the bottle. As soon as ³/₄ of the water has been pushed out of the bottle, take it out of the trough and set it aside. This bottle will not be used, as it contains mostly air from the gas generator.
8. Quickly invert the second bottle into the trough and begin to fill it with oxygen. As soon as the bottle is full, take it out of the trough. Place it right side up on the lab table and cover it with a glass square.
9. Continue collecting oxygen in this manner until 4 bottles have been filled with oxygen gas.

1. Examine the first bottle of oxygen gas:
   • What color is the gas?.
   • Uncover the bottle and cautiously determine if it has any odor.
   • Hold the uncovered bottle upside down for 1 minute. Light one end of a wood splint. Lift the bottle, holding it mouth down, blow out the burning splint, and push the glowing end of the splint into the bottle.
2. Uncover the second bottle of oxygen and leave it upright on the lab table for about 1 minute. Test it with a glowing splint as you did in the previous step.
3. Obtain the third bottle of oxygen.
   • Light a wood splint, blow out the flame, uncover the bottle, and plunge the glowing splint into the bottle. The splint should burst into flame.
   • Withdraw the splint, blow out the flame, and return the glowing splint to the bottle.
   • Continue doing this until the splint no longer relights, then cover the bottle with a glass square and record the number of times you were able to relight the splint.
   • Pour 10 ml of limewater into a 50 ml beaker.
   • Add 1 drop of phenolphthalein indicator to the beaker.
   • Use a dropper pipet to place about 25 drops of the limewater/indicator solution into the bottle you just tested.
   • Cover the bottle with the glass square and shake.
4. Place a pea-sized piece of sulfur into the bowl of a deflagrating spoon. Take the spoon of sulfur and the fourth bottle of oxygen to the fume hood.
   • Light a burner in the fume hood.
   • Turn on the hood fan. (Caution: sulfur produces choking gases when it burns. Make sure you have the fan on and the door of the hood pulled about half-way down before continuing.)
   • Hold the spoon of sulfur in the burner flame and observe how sulfur burns in air.
   • Remove the glass square from the oxygen bottle and plunge, do not drop, the bowl of the spoon into the bottle of oxygen and observe how sulfur burns in pure oxygen.
   • When finished, burn off any remaining sulfur in the burner flame while still in the hood.

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