POTASSIUM CHLORATE 247Apparatus: 500-cc. flask with 2-hole rubber stopper.
chlorine generator, use 2,000-cc. round-bottomed
flask.
suction filter and trap bottle,
iron ring and ring stand.
Bunsen burner.Procedure: Calculate the amount of manganese dioxide and
12 JV HC1 required to generate the chlorine necessary to react with
the alkalies. Take 10 per cent in excess of this amount and fit up
the chlorine generator. Dissolve the potassium and sodium hy-
droxides together in 70 cc. of water in the 500-cc. flask, but do not
filter the solution, even if it is not entirely clear. Arrange a wide
delivery tube to bubble chlorine into the alkali solution in the
flask, which is supported on a lamp stand so that it can be heated.
The exit tube from the flask is prolonged to a bottle containing
6N NaOH to absorb any excess chlorine. Pass chlorine into the
alkali solution until the latter is saturated with it. Let the reaction
heat the solution. Finally make sure that the solution is saturated
with chlorine. Remove the generator fittings, close the flask with
a solid rubber stopper, and shake vigorously; if the upper part of
the flask still contains chlorine gas the solution is saturated. Boil
the contents of the flask gently, avoiding " bumping," until the
excess of chlorine is expelled; then pour it all, still at boiling
temperature, on to the suction filter. Stop the suction before any
air has been drawn into the layer of crystals; add 15 cc. of water
to the flask, heat it to boiling, pour it on to the salt crystals in the
filter, and, after it has soaked in, apply the suction. In this way
nearly all the potassium chlorate is washed into the filtrate.
Cool the filtrate to 0° and collect the potassium chlorate crystals
on the suction filter. Dissolve the moist crystals in three times
their weight of water. If the solution is not clear, pour it through
a small common filter, rinsing the filter with 10 cc. of boiling water
to carry through any potassium chlorate which crystallized in the
filter. Purify by recrystallization until the product is free from
chloride. Preserve it in a 2-ounce cork-stoppered bottle.
A product of 15 grams is to be regarded as satisfactory. The
mother liquors should all have been saved to work over again if the
recrystallizations have not been skilfully enough carried out the
first time.