Synthetic Inorganic Chemistry

AMMONIUM BROMIDE 193

with the formation of sodium hypobromite and sodium bromide.

Br 2 + 2NaOH = NaBr + NaBrO + H 2 O

Sodium hypobromite reacts with ammonium hydroxide according

to the equation

3NaBrO + 2NH 4 OH = 3NaBr + 5H 2 O + N 2

If now we substitute NH4 for Na in the last two equations and

add the equations we obtain

3Br 2 + 8NH4OH -»• 6NH4Br + N 2 + 8H 2 O

which gives the complete reaction of bromine with ammonium

hydroxide.

Materials: bromine, Br 2 , 12.5 cc. = 40 grams = 0.25 F.W.

I5.ZVNH4OH = 44 cc.

Apparatus: 125-cc. separatory funnel.

300-cc. Erlenmeyer flask.

4-inch porcelain dish,

pan of cracked ice and water,

burette clamp,

ring stand,

mortar and pestle.

Procedure: Lubricate the stop cock of the dropping funnel
lightly with vaseline, and secure it in place with a rubber band,
so that it will not slip out when in use and let the bromine spurt
out over the fingers. Secure the funnel with a clamp to a ring
stand so that the bottom of the stem is about 1 inch above the
ice water. Place 50 cc. of water and the ammonium hydroxide in
the Erlenmeyer flask, float the latter in the ice water, and insert
the stem of the funnel in the flask so that it is kept from tipping
over. Pour the bromine into the funnel. Now, holding the bulb
of the funnel with the left hand, turn the stop cock with the right
hand to let one drop of bromine fall into the flask; quickly close
the stop cock and with the right hand grasp the flask and rotate
its contents. Proceed in this way until all the bromine is added,
working as rapidly as possible yet avoiding heating the flask and
causing white smoke and bromine vapor to belch out. If, when all
the bromine is added, the solution is yellow or red, add ammonium
hydroxide, a drop at a time, until the color disappears. Pour