The key difference between bismuth nitrate and bismuth subnitrate is that bismuth nitrate compound contains Bi3+ cation and nitrate anions, whereas bismuth subnitrate contains Bi3+ cations, nitrate anions, and oxide anions.
Bismuth nitrate and bismuth subnitrate are two related compounds because bismuth subnitrate is prepared from the bismuth nitrate compound.
What is Bismuth Nitrate?
Bismuth nitrate is a salt compound consisting of bismuth in +3 oxidation state and nitrate anions. Therefore, it is known as bismuth(III) nitrate. It has the most common pentahydrate solid form that is useful in the production of other bismuth-containing compounds. Bismuth nitrate is usually available commercially, and it is the only nitrate salt that forms from a group 15 element, which indicates the metallic nature of bismuth.
We can prepare bismuth nitrate from the reaction of bismuth metal and concentrated nitric acid. The chemical reaction is as follows:
Bi + 4HNO3 → Bi(NO3)3 + 2H2O + NO
The molar mass of bismuth nitrate is 485 g/mol. Its chemical formula can be given as Bi(NO3)3.5H2O. It appears as a white, colorless solid substance with a density of 2.90 g/cm3. Upon dissolving this compound in water, it decomposes to form bismuth oxynitrate. Moreover, it is slightly soluble in acid.
Usually, bismuth nitrate dissolves in nitric acid, but it is readily hydrolyzed to form a range of oxynitrates when the pH goes above 0. Moreover, this substance is soluble in acetone, acetic acid, and glycerol; however, practically, it is insoluble in ethanol and ethyl acetate. In addition, bismuth nitrate can form insoluble complexes with pyrogallol and cupferron. These compounds have been the basis of gravimetric methods for the determination of bismuth content.
What is Bismuth Subnitrate?
Bismuth subnitrate is also known as bismuth oxynitrate. It is a name that is applied to a number of compounds consisting of Bi3+, nitrate ions, and oxide ions. We can consider these compounds as they are formed from Bi2O3, N2O5, and H2O. Bismuth subnitrate is also known as bismuthyl nitrate.
In early times, this compound was used as a white pigment in beauty care and as a gentle disinfectant for internal and external applications. Moreover, this compound was used to form the Dragondorff reagent that is used in TLC stain. The chemical formula of bismuth subnitrate is BiH2NO5, and the molar mass is 305 g/mol. However, the commercially available form is given as Bi5O(OH)9(NO3)4.
Some compounds of bismuth subnitrate are fully characterized by single-crystal studies, and according to these studies, these compounds have an octahedral cation structure. Indirect evidence says that either the octahedral cation Bi6O4(OH)46+ or the octahedral cation Bi6(OH)126+ occurs in an aqueous solution.
We can prepare bismuth subnitrate from bismuth(III) nitrate. Hydrolysis of a solution of bismuth nitrate through the addition of alkali or the reaction of the pentahydrate form with KOH or the controlled thermal decomposition of the pentahydrate gives bismuth subnitrate.
What is the Difference Between Bismuth Nitrate and Bismuth Subnitrate?
Bismuth nitrate and bismuth subnitrate are inorganic salt compounds of bismuth. The key difference between bismuth nitrate and bismuth subnitrate is that bismuth nitrate compound contains Bi3+ cation and nitrate anions, whereas bismuth subnitrate contains Bi3+ cations, nitrate anions, and oxide anions.
Summary – Bismuth Nitrate vs Bismuth Subnitrate
Both bismuth nitrate and bismuth subnitrate have bismuth atoms in their +3 oxidation state and nitrate anions. The key difference between bismuth nitrate and bismuth subnitrate is that bismuth nitrate compound contains Bi3+ cation and nitrate anions, whereas bismuth subnitrate contains Bi3+ cations, nitrate anions, and oxide anions.
1. “CN103253706A – Preparation Method of Basic Bismuth Nitrate.” Google Patents, Google.
1. “Dusičnan bismutitý” By Ondřej Mangl – Own work (Public Domain) via Commons Wikimedia
2. “Bismuth, iodoform & paraffin paste (bipp) & Whitehead’s Varnish” By John Doran (CC BY-NC-SA 2.0) via Flickr