How to Make Gases Safely for Chemistry

Chemistry glassware
Special glassware makes gas collection easier and safer.

 Benjamin Taguemount / Getty Images

You can use common chemistry lab chemicals and equipment to prepare several gases. 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.

Helpful Equipment for Preparing Gases

Many gases can be prepared using nothing more complicated than a length of tubing, but other items that are handy to have include:

  • Conical flask
  • Thistle funnel
  • Delivery tube
  • Pneumatic trough
  • Beehive
  • Burner or hot plate

You may wish to consult more detailed instructions if you are unclear how to proceed. Please remember, many common lab gases are flammable and/or toxic!

Gas Reagents Method Collection Reaction
Ammonium chloride

Calcium hydroxide
Gently heats 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
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
Potassium permanganate
Conc. Hydrochloric acid
Add concentrated hydrochloric acid dropwise onto a few potassium permanganate crystals (in the flask). Upward displacement of air in a hood. 6HCl + 2KMnO4 + 2H+ → 3Cl2 + 2MnO2 + 4H2O + 2K+
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
Sodium chloride
Conc. Sulfuric acid
Slowly adds concentrated sulfuric acid to solid sodium chloride. Displacement of air in a hood. 2NaCl + H2SO4 → Na2SO4 + 2HCl
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
Calcium hypochlorite (bleaching powder)
Shake 20 g calcium hypochlorite into 100 mL water for several minutes, then filter. Add 10 mL cons. ammonia and heat mixture. Use extreme caution! Chloramine and explosive nitrogen trichloride may be produced. Displacement of air. 2NH3 + 3CaOCl2 → N2 + 3H2O + 3CaCl2
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
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
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
Sodium nitrate
Ammonium sulfate
Mix 10 g powdered sodium nitrate and 9 g ammonium sulfate. Heat well. Displacement of air. NH4NO3 → N2O + 2H2O
6% Hydrogen peroxide
Manganese dioxide (catalyst)
Add hydrogen peroxide to about 5 g of MnO2. Collect over water. 2H2O2 → 2H2O + O2
Potassium permanganate Heat solid KMnO4. Collect over water. 2KMnO4 → K2MnO4 + MnO2 + O2
Sulfur Dioxide
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
Table: How To Make Gases