314 ELEMENTS OF GROUP Vregulus of antimony. Crack the regulus so as to show the crystal-
line structure of the metal.QUESTIONS- Warm a piece of metallic antimony with hydrochloric acid.
Where does antimony stand in the electromotive series? - Boil 0.5 gram of powdered antimony in a small flask with 6 N
HN0 3. Describe the result and write equations remembering that
Sb 2 O 3 is basic and gives a soluble nitrate with HN0 3 , but that
Sb 2 O 6 (H 3 Sb04) is an acidic oxide.
PREPARATION 60
BISMUTH BASIC NITRATE (BISMUTH SUBNITRATE),
Bi(OH) 2 NO 3 OR BiONO 3
Bismuth is the most strongly metallic element of the fifth group,
yet its salts in aqueous solution undergo partial hydrolysis very
readily. In presence of a considerable amount of free acid, the
Bi+++ ion is capable of existence in solution; but with decreasing
quantities of acid the tendency to hydrolyze increases, and the
basic salt of bismuth, which is only slightly soluble, separates:
Bi(NO 3 ) 3 + 2H 2 O ^ Bi(OH) 2 NO 3 1 + 2HNO 3
On pouring a solution of bismuth nitrate into a considerable
quantity of cold water the basic nitrate is precipitated, according
to the above formula. This salt, however, is not stable in con-
tact with a solution which does not contain nitric acid of a con-
centration of at least 0.5 molal, but slowly changes over into some
other more basic nitrate, and if washed repeatedly with pure water
will finally go over completely into the hydroxide:
Bi(OH) 2 NO 3 + H 2 O ^ Bi(OH) 3 J, + HN0 3Under the conditions in the following procedure, this production
of a more basic salt will occur if the precipitate is allowed to stand
in contact with the solution for a considerable time; hence the
directions to filter at once.
The basic nitrate is by no means completely insoluble in water,
and the filtrate contains considerable quantities of bismuth, which
can be conveniently saved as oxide by precipitating with sodium
carbonate.