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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Bismuthyl (ion) | 2/2 | https://en.wikipedia.org/wiki/Bismuthyl_(ion) | reference | science, encyclopedia | 2026-05-05T16:14:07.583526+00:00 | kb-cron |
The classic method for obtaining bismuthyl salts was the treatment of bismuth oxide (Bi2O3) with nitric acid. This reaction produces bismuthyl salts such as BiO(NO3 and Bi2O2(OH)(NO3) as end products. The same bismuthyl salts precipitate when strongly acidic solutions of various bismuth compounds are diluted. The formation of bismuthyl was also considered to be a process that constantly occurs as a result of hydrolysis. Thus, bismuth nitrate, Bi(NO3)3 • 5H20, crystallizes from a solution resulting from the reaction of bismuth with nitric acid. It dissolves in a small amount of water acidified with nitric acid. However, when the solution is diluted with larger quantities of water, hydrolysis occurs and basic salts precipitate, the composition of which depends on the conditions. A salt of the composition BiONO3 is often formed. Bismuthyl chloride (BiOCl) is readily soluble in hydrochloric acid. Moreover, this process, like nitrate, proceeds through a reversible reaction; a shift of the reaction to the left or right also occurs along the line of hydrolysis, depending on the relative amount of water and the (residual) hydrochloric acid present. Adding water to a slightly acidic solution of ВіСl3 immediately causes the appearance of a white precipitate of basic bismuth chloride, BiOCl. When hydrochloric acid is added, the precipitate dissolves again, but it immediately falls out when more water is added. All other bismuth compounds behave in aqueous solutions similarly to chloride. In more detail, the ongoing hydrolysis reactions using bismuth chloride as an example are usually represented by the following reversible equations:
BiCl3 + H2O ↔ BiOHCl2 + HCl BiOHCl2 + H2O ↔ Bi(OH)2Cl + HCl The resulting dihydroxobismuth chloride is unstable and easily splits off a water molecule:
Bi(OH)2Cl = BiOCl + H2O The output is a basic salt containing a bismuthyl cation BiO+, i.e. ″bismuthyl″ chloride. Bismuth nitrate is hydrolyzed in the same way, forming the main salt of the composition BiONO3. However, the reaction with it in an aqueous environment is much less successful and does not have such a clear result, since the resulting bismuthyl nitrate is much more soluble in water than its chloride. The hydrolysis reaction of bismuth salts is reversible, and therefore when heated and hydrochloric acid is added to the precipitate, it dissolves again:
BiOCl + 2HCl = BiCl3 + H2O When the solution is diluted again with water, a precipitate of the basic salt precipitates again. The main mechanism in such reactions is the pronounced amphotericity of X(ОН)3 hydroxides for arsenic and antimony and the basic properties for bismuth, as a result of which the salts are susceptible to hydrolysis, especially in the case of antimony and bismuth, which are characterized by the formation of antimonyl cations SbO+ and bismuthyl BiO+. According to this principle, Bi(OH)3, losing water when heated, turns into yellow bismuthyl hydroxide with the formula BiO(OH), sparingly soluble in water, which upon further dehydration forms Bi2O3 oxide. At elevated temperatures, the vapors of the metal combine rapidly with oxygen, forming the yellow trioxide, Bi2O3. When molten, at temperatures above 710 °C, this oxide corrodes any metal oxide and even platinum. On reaction with a base, it forms two series of oxyanions: BiO−2, which is polymeric and forms linear chains, and BiO3−3. The anion in Li3BiO3 is a cubic octameric anion, Bi8O24−24, whereas the anion in Na3BiO3 is tetrameric. In addition to bismuthyl itself, thiocompounds corresponding to bismuthyl salts are also considered indicative for the chemistry of bismuth, for example, gray thiobismuthyl chloride with the formula BiSCl and others similar to it. These substances, unlike bismuthyl salts, are very stable with respect to water, and can be easily prepared by the action of hydrogen sulfide gas on the corresponding bismuth trihalide.
== Practical significance == The mineral bismoclite (bismuthyl chloride) has a traditional use as one of the secondary bismuth ores that are constantly formed in oxidation zones. When mixed with other associated ores, it will become the raw material for the production of pure bismuth and its compounds. In medical diagnostics, bismoclite (in the form of purified bismuth oxychloride) is used as a local radiocontrast agent. In addition, in the production of cosmetics, bismoclite is used as an enhancing additive; it gives a pearlescent shine to lipstick, nail polish and eye shadow. In the chemical industry, in the process of cracking hydrocarbons, bismuthyl chloride is used as a catalyst. The bismuthyl cation is also widely involved in the synthesis of bismuth-organic compounds, including those with pharmaceutical applications.
== References ==
== See also == Bismuthyl Bismuthyl chloride Bismuthyl carbonate Bismuthyl nitrate Bismoclite