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Bismuth/ions/salts determination

Determination of silver as chloride Discussion. The theory of the process is given under Chloride (Section 11.57). Lead, copper(I), palladium)II), mercury)I), and thallium)I) ions interfere, as do cyanides and thiosulphates. If a mercury(I) [or copper(I) or thallium(I)] salt is present, it must be oxidised with concentrated nitric acid before the precipitation of silver this process also destroys cyanides and thiosulphates. If lead is present, the solution must be diluted so that it contains not more than 0.25 g of the substance in 200 mL, and the hydrochloric acid must be added very slowly. Compounds of bismuth and antimony that hydrolyse in the dilute acid medium used for the complete precipitation of silver must be absent. For possible errors in the weight of silver chloride due to the action of light, see Section 11.57. [Pg.467]

The most widely used titrant for such determinations is diamino-ethane-tetra-acetic acid (ethylenediamine tetra-acetic acid) which is conveniently employed as the disodium salt, referred to throughout this book as EDTA. (The titrant is referred to in the B,P, and B,P,C, as sodium edetate, but this synonym has not gained universal acceptance.) Many other amino-polycarboxylic acids have been used and in certain special applications they may have some advantage for routine pharmaceutical work, however, it has not been found necessary to use any titrant other than EDTA. This substance reacts stoichiometrically with most metals to form a 1 1 complex and, usually, the reaction is instantaneous (but see Aluminium, p. 32). pH has a marked effect on the stability of the complexes formed the alkaline earth metals form complexes that are stable in alkaline solution but decompose in neutral and acid solution aluminium, copper, lead and mercury all complex under mildly acid conditions while bismuth and ferric iron form stable complexes in a solution as acid as pH 1. The monovalent ions of sodium, potassium and silver form complexes that are too weak to be used for titration purposes whilst mercurous mercury forms no complex,... [Pg.786]


See other pages where Bismuth/ions/salts determination is mentioned: [Pg.127]    [Pg.127]    [Pg.401]    [Pg.337]    [Pg.1483]    [Pg.204]    [Pg.173]    [Pg.437]    [Pg.612]    [Pg.336]    [Pg.1482]    [Pg.708]    [Pg.216]    [Pg.206]    [Pg.178]    [Pg.411]   
See also in sourсe #XX -- [ Pg.560 ]




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