Chemical Concept Demonstrated

• Chemical gas production

Demonstration

One of the following apparati should be built:  a 500-mL Erlenmeyer flask with a two-hole stopper to which a dropping funnel and a glass delivery tube have been attached, or a 500-mL filter flask fitted with a one-hole stopper and a dropping funnel.

Collection should take place via the downward displacement of water (if the gas doesn't react with water) or the downward or upward displacement of air (depending on the relative density of the gas).  Gas should be collected in a balloon to be easily accessible in a lecture demonstration (see 4.1 video and 4.2 demonstration sheet and video).

The following gases can be produced by the methods provided:

• Acetylene (C₂H₂): Place 20 g CaC₂ in the apparatus and add water at the rate of two to three drops per minute
• Ammonia (NH₃): Small amount: water to magnesium nitride (Mg₂N₂) / Large amount: Warm concentrated aqueous ammonia (drying tube required) or add concentrated aqueous ammonia to solid NaOH
• Carbon Dioxide (CO₂): Either add 6 M HCl to 20 g chalk, marble, limestone, or dolomite or evaporate dry ice.
• Chlorine: Add ~1 g KMnO₄ to concentrated HCl
• Hydrogen (H₂): React ~45 g mossy zinc or aluminum turnings with 6 M HCl
• Nitrogen Oxide (NO): Add 6 M nitric acid to 20-30 g of copper turnings (note: this produces NO₂ when the reaction first begins)
• Nitrogen Dioxide (NO₂): Add air to NO (tip: collect the product of the NO-producing reaction listed above by the upward displacement of air to produce NO₂)
• Oxygen: Add 3 g MnO₂ or KMnO₄ to 30 mL of 3% H₂O₂ in the presence of a small quantity of sulfuric acid

Contributors 

• Dr. George Bodner (Perdue University)

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