BARIUM OXIDE AND BARIUM HYDROXIDE 2015-inch filter funnel and filter.
5-inch watch glass.
500-cc. flask,
iron ring and ring stand.
Bunsen burner.Procedure: Mix the finely powdered barium carbonate with
10 grams of powdered charcoal and 5 grams of powdered rosin.
After mixing the whole mass very thoroughly in a mortar, place
it in the crucible, press it down firmly, and cover it with a layer
of charcoal at least \ inch deep. Place a well-fitting cover on the
crucible and heat the whole for 1 hour in the gas furnace to as
high a temperature as possible. After the crucible has cooled,
remove the top layer of charcoal, place the barium oxide in the
porcelain dish, and very cautiously add a few drops of water,
noting the very violent reaction. Finally add 400 cc. of water,
and heat the mixture in the dish to boiling; pour the solution
through a large, ordinary filter (Note 4 (c), page 7), letting the
clear liquid run directly into a 500-cc. flask and keeping the funnel
covered with a watch glass to prevent cooling during the filtration.
Rinse the residue in the dish with 75 cc. more of boiling water, and
pour this upon the filter after the first portion has nearly all run
through. Stopper the flask and allow the solution to cool slowly
to room temperature; finally, cool it nearly or quite to 0°; collect
the crystals on a suction filter; wrap the product in paper towels
and leave it over night to dry at room temperature (Note 9 (6),
page 15). Put the product in an 8-ounce cork-stoppered bottle.
QUESTIONS- How does barium hydroxide become contaminated by ex-
posure to the air? Why might this product be dried with less
contamination by exposure to the air out-of-doors than to the air
of the laboratory? - The mineral witherite often contains barium sulphate as
an impurity. State what changes this substance would undergo
during the above process. How could barium hydroxide be pre-
pared from barium sulphide? (Compare preparation of stron-
tium hydroxide from strontium sulphate, page 194.) - Devise a method for preparing barium hydroxide from
barium carbonate by which the use of a furnace may be avoided.