Aqueous sodium hydroxide and Devarda's
alloy or aluminium foil/powder is a specific test mixture
used to detect nitrate ions in solution. When the mixture
is heated with nitrate ions in solution, vigorous effervescence
occurs and ammonia gas is evolved.
The nitrate ions are reduced by
the Devarda's alloy or aluminium metal to form ammonia
gas.
a) Test for Nitrate ions in solution,
NO3- (aq)
Experiment
4:
To
identify an aqueous solution of sodium nitrate using
dilute sodium hydroxide solution and Devarda's alloy
or aluminium foil.
Place 2 cm3 of sodium nitrate solution
in a test tube. Add an equal volume of dilute
sodium hydroxide solution.
Add a small amount of Devarda's alloy or 2 pieces
of aluminium foil.Warm mixture.
