Qualitative analysis / by William Briggs and R.W. Stewart.

  • William Briggs
Date:
1913
Catalogue details

Licence: Public Domain Mark

Credit: Qualitative analysis / by William Briggs and R.W. Stewart. Source: Wellcome Collection.

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    3. Potassium chromate, K2Cr04, gives a yellow precipitate of the basic chromate, Bi90(Cr04)2— 2 K2Cr04 + 2 Bi(N03)3 + H90 = Bi20(Cr04)2 + 4 Ktt03 + 2 HN03. The precipitate is soluble in dilute nitric acid, but insoluble in sodium hydroxide. [Distinction from leadf\ 4. Dilute sulphuric acid, H2S04, gives no precipitate. IDistinction from lead.~\ 5. Caustic potash, KOH, gives a white precipitate of bismuth hydroxide, Bi(OH)3, insoluble in excess— 3 KOH + Bi(N03)3 = Bi(OH)3 + 3 KN03. NaOH and NH4OH behave in a similar manner. j 6. Add caustic potash to stannous chloride, SnCl2, till the precipitate of stannous hydroxide first formed redissolves, forming potassium stannite, K2Sn02. Kow add a solution of a bismuth salt. A black precipitate of bismuth dioxide, Bi202, is formed. 2 KOH + SnCl9 = Sn(0H)9 + 2 KC1. 2 KOH + Sn(OH)2 = K2Sn02 + 2 H20. K2Sn09 + 6 KOH + 2 Bi(N03)3 = Bi009 + K9Sn03 + 6 KN08-+ 3 H20. 7. Mix with sodium carbonate, Na2C03, and heat on charcoal before the blowpipe in the reducing flame : brittle metallic beads are obtained, and an orange-yellow incrustation is formed on the charcoal. Most of the soluble bismuth salts are decomposed by water, in¬ soluble basic salts being formed. Bismuth nitrate, Bi(N03)3, the commonest salt, dissolves in a small quantity of water, especially if nitric acid is present. A large quantity of water decomposes the salt, and basic bismuth nitrate (bismuthyl nitrate or bismuth oxynitrate), BiON03, is formed.