Synthetic Inorganic Chemistry

154 NON-METALLIC ELEMENTS IN BINARY COMPOUNDS

Procedure: Mix the aluminum powder and lampblack thor-

oughly in a mortar. Heap up the mixture in as compact a mound

as possible on the asbestos paper. The latter must be placed on

a thick iron plate and in a safe location, for the heat will be so in-

tense as to burn through the asbestos. Insert the magnesium

ribbon 0.5 inch into the top of the pile and light the free end from

the gas flame. The temperature of the burning magnesium is high

enough to set fire to the mixture, but the spot thus ignited is quite

likely to cool off before the combustion can get well started. As

soon as the ribbon has burned down to the surface of the pile,

play the gas flame over the hot spot, until the combustion is

thoroughly under way. Although the Bunsen flame alone is not

hot enough to bring the mixture to the kindling point, it prevents

the spot heated by the magnesium from cooling rapidly. Watch

the combustion spread throughout the mixture, but do not look

at the intense light for more than a second at a time unless the

eyes are protected with colored glasses. When the ash is cool,

break it up, remove as much as possible of the white aluminum

oxide crust from the outside, and preserve the nitride in a 4-ounce

cork-stoppered bottle.

QUESTIONS

1. Examine the aluminum nitride and describe its appearance.


2. Treat a little with cold water and then with hot water. Is
   there any reaction?


3. Treat a little with NaOH solution and warm. Is am-
   monia given off? What type of reaction is this? (See next
   preparation.)


4. Why does the hydrolysis of aluminum nitride take place in
   NaOH solution but not in pure water? (See Experiment 9,
   Chapter II, p. 69.)


5. Heat a little aluminum nitride in the open air to see how
   easily it can be converted to oxide.

PREPARATION 14
MAGNESIUM NITRIDE, Mg 3 N 2
AMMONIUM CHLORIDE, NH 4 C1
Magnesium nitride is prepared by the same general principle
as that employed in preparing aluminum nitride (Preparation 13).
If, however, a pile of magnesium were allowed to burn freely in the