PREPARATION OF GASES
Gas
Ammonia
NH3
Reagents
Ammonium
chloride
Method
Collection
Gently heat a mixture of ammonium chloride and
calcium hydroxide in water.
Upward
displacement of air
in a hood.
Ca(OH)2 + 2NH4Cl --> 2NH3
+ CaCl2 + 2H2O
Add 5 M hydrochloric acid to 5 - 10 g marble chips.
Upward
displacement of air
in a hood.
2HCl + CaCO3 --> CO2 +
CaCl2 + H2O
Calcium hydroxide
Reaction
Carbon
Dioxide
CO2
Calcium carbonate
(marble chips)
5 M Hydrochloric
acid
Chlorine
Cl2
Potassium
Add concentrated hydrochloric acid dropwise onto a
permanganate
small amount of potassium permanganate crystals (in
Conc. Hydrochloric
flask).
acid
Upward
displacement of air
in a hood.
6HCl + 2KMnO4 + 2H+ -->
3Cl2 + 2MnO2 + 4H2O + 2K+
Hydrogen
H2
Zinc (granulated)
5 M Hydrochloric
acid
Add 5 M hydrochloric acid to 5 - 10 g granulated zinc
pieces.
Collect over water.
2HCl + Zn --> H2 + ZnCl2
Hydrogen
Chloride
HCl
Sodium chloride
Conc. Sulfuric acid
Slowly add concentrated sulfuric acid to solid sodium
chloride.
Displacement of air
in a hood.
2NaCl + H2SO4 --> Na2SO4 +
2HCl
Methane
CH4
Sodium acetate
(anhydrous)
Soda lime
Mix 1 part sodium acetate with 3 parts soda lime. Heat
in a dry pyrex test tube or flask.
Collect over water.
CH3COONa + NaOH --> CH4
+ Na2CO3
Nitrogen
N2
Ammonia
Calcium
hypochlorite
(bleaching powder)
Shake 20 g calcium hypochlorite into 100 mL water for
several minutes, then filter. Add 10 mL conc. ammonia
and heat mixture. Use extreme caution! Chloramine and
explosive nitrogen trichloride may be produced.
Displacement of air.
2NH3 + 3CaOCl2 --> N2 +
3H2O + 3CaCl2
Nitrogen
N2
Invert a bell jar over lighted phosphorus. Oxygen and
Air
phosphorus combine to form phosphorus pentoxide,
Lighted Phosphorus
which is absorbed by the water over which the bell jar
(or heated Fe or
stands (may be violent reaction), producing phosphoric
Cu)
acid and leaving the nitrogen behind.
Removal of oxygen.
5 O2 + 4 P --> P4O10
Nitrogen
Dioxide
NO2
Copper (turnings)
10 M Nitric acid
Add concentrated nitric acid to 5 - 10 g copper.
Upward
displacement of air
in a hood.
Cu + 4HNO3 --> 2NO2 +
Cu(NO3)2 + 2H2O
Nitrogen
Monoxide
NO
Copper (turnings)
5 M Nitric acid
Add 5 M nitric acid to 5 - 10 g copper.
Collect over water.
3Cu + 8HNO3 --> 2NO +
3Cu(NO3)2 + 4H2O
Nitrous
Oxide
N2O
Sodium nitrate
Ammonium sulfate
Mix 10 g powdered sodium nitrate and 9 g ammonium
sulfate. Heat well.
Displacement of air.
NH4NO3 --> N2O + 2H2O
Oxygen
O2
6% Hydrogen
peroxide
Manganese dioxide
(catalyst)
Add hydrogen peroxide to about 5 g of MnO2.
Collect over water.
2H2O2 --> 2H2O + O2
Oxygen
O2
Potassium
permanganate
Heat solid KMnO4.
Collect over water.
2KMnO4 --> K2MnO4 +
MnO2 + O2
Sulfur
Dioxide
SO2
Sodium sulfite (or
sodium bisulfite)
2 M Hydrochloric
acid
Add dilute hydrochloric acid to 5 - 10 g sodium sulfite
(or bisulfite).
Upward
displacement of air
in a hood.
Na2SO3 + 2HCl --> SO2 +
H2O + 2NaCl
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