| 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
|