MAGNESIUM NITRIDE AND AMMONIUM CHLORIDE 155open air, a much greater conversion of nitride into oxide would
occur before the reaction died out. The reaction is, therefore,
more carefully regulated by being carried out in a crucible which
is heated from an external source.
Magnesium nitride differs from aluminum nitride in that it
hydrolyzes rapidly with pure water; in fact, it does so with con-
siderable violence. Insoluble magnesium hydroxide and volatile
ammonia are formed.
Mg 3 N 2 + 6H 2 O = 3Mg(OH) 2 + 2NH 3Materials: powdered magnesium, 10 grams,
dry sand, 50 grams.
Apparatus: iron crucible of 25-cc. capacity and cover,
two 300-cc. flasks.
500-cc. filter flask.
125-cc. separatory funnel.
8-inch U-tube.
4-inch porcelain dish,
thistle tube.
three 2-hole rubber stoppers,
one 1-hole rubber stopper,
asbestos paper,
wire triangle.
iron ring and 2 ring stands.
Bunsen burner,
mortar and pestle.Procedure: Weigh an iron crucible of about 25-cc. capacity to-
gether with the cover. Pack it even full with powdered magne-
sium, tapping the crucible on the desk to make the powder settle.
Weigh the filled crucible; it should hold about 10 grams of the
powder. Place the cover tightly on top; surround the crucible
on the triangle with a cylinder of asbestos 3 inches in diameter so
as to diminish the loss of heat by radiation. Heat the crucible as
hot as possible with a Bunsen burner for 45 minutes. After it cools
empty the crucible on to a piece of paper and note the white MgO
on top and the yellow Mg 3 N 2 beneath. Place the material in a
mortar, break up the lumps, add 25 grams of dry coarse sand, and
mix well. Then place 25 grams of sand in the bottom of a dry
300-cc. flask and pour the mixture from the mortar on top of it.