Aids and chemicals  Working process  Preparation of O2 Oxygen detection Reactions with oxygen Observation  Interpretation  Remarks  Exhalates annihilation  Safety

Aids and chemicals:

	for O2 preparation: gas evolver (test tube with side hole and separator tube), stand, clamp, holder, beaker (100 cm3), test tube holder and stand, H2O2 solution (w = 10%), burel tablets
	MnO2 - catalysator (prepared of 2 cement portion, 1 burel portion and water, the leave to dry in plastic coat), plumbum Pb,  ethanol C2H5OH, chip, cigarette, burner
	simple gas evolver: film coat, stopper punched by 2 hypodermic needles (1,2 x 40 mm), 10 cm3 hypodermic syringe, 20 cm3  hypodermic syringe (with rubber plunger coated with silicone oil), beaker (for H2O2), paper

Working process:

Preparation of O2  Put 5 tablets of catalysator (burel  MnO2) into simple gas evolver and close with rubber plunger that is punched by 2 hypodermic needles. Add slowly H2O2 solution (w = 10%) from 10 cm3 hypodermic syringe while 20 cm3  hypodermic syringe is filled O2. Put new hypodermic needle on hypodermic syringe with O2. Prepared O2 can be used in next experiments.  2 H2O2 ---------> 2 H2O + O2    Preparation of more amount of O2 from H2O2 for various reactions. Gas evolver - fill with 10 tablets of burel MnO2. Drop H2O2 (w = 10%) to tablets from syringe. Oxygen is evolved. With the help of tube with 50 cm3 syringe O2 can be removed from side hole of the test tube and used in various experiments. Preparation O2 from H2O2 (detection in the test tube)   As a catalysator for H2O2 decomposition freshly founded Pb sheet is used (melt Pb, let drop to fire - proof ladle a wait untill it is cold). Fill the test tube 5 cm under edge with H2O2 (w = 30%), water H2O and ethanol C2H5OH in ratio 1 : 1 : 1. After adding the catalysator burn ethanolic vapours, which are rich in O2. In consecutive heating there are repeated explosions.

 

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Reaction of O2  with H2   Fill the syringe with 6 cm3 of O2.  From other simple gas evolver fill it with 12 cm3 of H2.  Put this explosive gas into soap solution and burn bubles.

 

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Observation

O2 is evolved in catalytical decomposition of H2O2, and O2 supports burning.

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 Vysvetlenie

2 H2O2 ---------> 2 H2O + O2

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Remarks

	Use high grade powdered burel in preparation of catalysator tablets .
	As founding forms use various plastic coats.

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Exhalate annihilation

	No dangerous substance is evolved in these experiments.
	Cleaning the apparature is very simple.

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Safety

	10% solution of H2O2 dip the skin, prevent the skin from direct contact with H2O2.
	Prevent the simple gas evolver from over pressure.
	Do not breathe powdered burel!
	Use protection shield!

Posledná aktualizácia: 26.11.2000