284 ELEMENTS OF GROUP IVIf cerous oxalate is strongly heated in air, the water of crystal-
lization is first driven off, then the cerous oxalate decomposes into
cerous oxide and oxides of carbon. The cerous oxide is oxidized
by the oxygen in the air to eerie oxide.Material: Cerous oxalate, Ce 2 (C 2 O4) 3 -10H 2 O,72.5 grams = 0.1
F.W.
Apparatus: 6-inch iron sand bath,
iron ring and ring stand.
Bunsen burner.Procedure: Pour the cerous oxalate into the clean iron sand bath.
Support the pan on an iron ring and heat with a long blue flame
with no cone. The flame should be long enough to be in contact
with all parts of the pan, but it should not appear above the rim.
The solid should be stirred frequently to insure complete decompo-
sition. When the solid is no longer white, the temperature should
be increased and the pan heated for 10-15 minutes with a hot flame.
Cool, weigh the pan plus the solid, and heat again until the weight
is approximately constant. Put the product in an 8-ounce cork-
stoppered bottle.
QUESTIONS- Pour 4-5 cc. concentrated hydrochloric acid on 0.5 gram of
the product. Equation? - Heat 0.5 gram of the product in a test tube with 5 cc. con-
centrated nitric acid. Equation? To what is the color due?
PREPARATION 50
CEROUS OXALATE, Ce 2 (C 2 O4)3- 10H 2 O
In the quantitative determination of cerium, use is made of
the fact that cerous oxalate is insoluble in neutral and acid solu-
tion. Since a quantitative yield is not necessary in this prepara-
tion, some of the cerium is sacrificed to insure complete removal
of any iron that may be present. In order to have a neutral
solution for the hydrolysis of the iron, a slight excess of eerie
oxide is used.
From the discussion of the preparation of eerie oxide it is evi-
dent that the cerous oxide, Ce 2 O 3 , which would be the direct