Important bismuth compounds

Bismuth(III) carbonate dioxide : (bismuthyl carbonate; Bi₂O₂CO₃) A white solid prepared by mixing solutions of bismuth nitrate and ammonium carbonate.  It contains the (BiO)⁺ ion. 

Bismuth(III) chloride (bismuth trichloride; BiCl₃) A white deliquescent solid. It can be prepared by direct combination of bismuth and chlorine. Bismuth(III) chloride dissolves in excess dilute hydrochloric acid to form a clear liquid, but if diluted it produces a white precipitate of bismuth(III) chloride oxide (bismuthyl chloride, BiOCl):

BiCl₃ + H₃O → BiOCl + 2HCl

This reaction is often used as an example of a reversible reaction and as a confirmatory test for bismuth during quantitative analysis. Bismuth(V) chloride does not form. 

Bismuth(III) nitrate oxide (bismuthyl nitrate; BiONO₃) A white insoluble solid, often referred to as bismuth subnitrate. It is precipitated when bismuth(III) nitrate is diluted and contains the (BiO)⁺ ion. Bismuth( III) nitrate oxide is used in pharmaceutical preparations.