Objective - Determine the percentage of
oxygen in potassium chlorate (KClO3).
The decomposition of potassium chlorate (at temperatures above
400oC) is described by the equation:
A weighed sample of potassium chlorate will be heated until all
the oxygen is released. The relative amounts of oxygen and potassium chloride
(KCl) will be measured by determining the amount of residue (KCl) which remains
after heating. The decrease in weight after heating will represent the amount
of oxygen originally present in the sample.
To test that the residue is potassium chloride it will be dissolved
in water, acidified and then tested with silver nitrate (AgNO3) solution. If
the residue is potassium chloride then the acidified solution will react with
the silver nitrate solution producing silver chloride (AgCl), which will appear
as a white precipitate.