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How to Prepare Gases

Chemistry Lab Instructions

You can use common chemistry lab chemicals and equipment to prepare several gases. A conical flask, thistle funnel, delivery tube, pneumatic trough, and beehive are useful items to have on hand. Please make sure you are familiar with the use and functioning of the laboratory equipment you use, are aware of the characteristics of the substances (toxicity, flammability, explosivity, etc.), and take proper safety precautions. Use a ventilation hood (fume cupboard) and keep flammable gases away from heat or flame. I've tried to be as accurate as possible in my instructions, but you use them at your own risk. For convenience, I've listed the gases in alphabetical order.

Gas	Reagents	Method	Collection	Reaction
Ammonia NH3	Ammonium chloride Calcium hydroxide	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
Carbon Dioxide CO2	Calcium carbonate (marble chips) 5 M Hydrochloric acid	Add 5 M hydrochloric acid to 5 - 10 g marble chips.	Upward displacement of air in a hood.	2HCl + CaCO3 → CO2 + CaCl2 + H2O
Chlorine Cl2	Potassium permanganate Conc. Hydrochloric acid	Add concentrated hydrochloric acid dropwise onto a small amount of potassium permanganate crystals (in flask).	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	Air Lighted Phosphorus (or heated Fe or Cu)	Invert a bell jar over lighted phosphorus. Oxygen and phosphorus combine to form phosphorus pentoxide, which is absorbed by the water over which the bell jar stands (may be violent reaction), producing phosphoric 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

مرجع: http://chemistry.about.com/library/weekly/aa020603a.htm