318 ELEMENTS OF GROUP Ving and cooling until the precipitate formed at first is redis-
solved. Pour this solution over the filter paper, and note the
intense black color.Bismuth stands low in the electromotive series, and its salts
are easily reduced to the metal which in the finely divided state is
intensely black.
2Bi(OH) 3 + 3Na 2 Sn0 2 -> 2Bi 1 + 3Na 2 Sn0 3 + 3H 2 O- Bismuth in a Higher State of Oxidation. Fusion of bismuth
salts with sodium hydroxide and an oxidizing agent yields a ma-
terial which has been called sodium bismuthate, from the hypo-
thetical oxide Bi 2 C>6. Such a compound has never been obtained
pure. If the melt is extracted with water, the salt hydrolyzes
completely and analysis of the brown residue gives a composition
approximating the formula BiO 2 , rather than Bi 2 O 6.
Add 1 drop of Mn(NO 3 ) 2 or MnSO 4 solution (but not
MnCl 2 ) to 5 cc. of cold 6N HNO 3. Add about 0.1 gram
solid bismuth dioxide, agitate, let the brown solid settle, and
note the deep red permanganate color of the solution.
Bismuth in a higher state of oxidation than that corresponding
to the oxide Bi 2 O 3 must be a very strong oxidizing agent if it can
oxidize a manganese compound to permanganic acid.
Mn(NO 3 ) 2 + 13HNO 3 + 5BiO 2 -> 5Bi(NO 3 ) 3 + HMnO 4 + 6H 2 O
GENERAL QUESTIONS X
ELEMENTS OF GROUP V- State in each case whether the nitrate or sulphate of tri-
valent phosphorus, arsenic, antimony, or bismuth can be prepared,
and if so whether it can be dissolved in water without suffering
complete hydrolysis. How does the basic nature of the trioxide
change in the series phosphorus to bismuth? Can nitrates or
sulphates of any of these elements in their pentavalent condition
be prepared? For any one of the elements, which is the more
strongly basic in nature, the trioxide or the pentoxide? Which
is the more strongly acidic? Give the formula of the most common
acid, if one exists, which is derived from the pentoxide of each of
these elements. How does the acidic nature of the pentoxide
change in passing from nitrogen to bismuth?