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

  • Briggs, William, 1861-1932.
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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    1? hydrochloric acid, which converts it into insoluble silver chloride. Ag2Cr04 + 2 HC1 = 2 AgCl + H2Cr04. 3. Potassium cyanide, KCN, gives a white curdy pre cipitate of silver cyanide, AgCN, very soluble in excess of KCN with formation of KAg(CN)2. • AgN03 + KCN = AgCN + KN03. AgCN + KCN = KAg(CN)2. If the solution is rubbed upon a bright piece of copper, a white stain of silver is produced. This stain does not disappear on heating. 4. Caustic potash, KOH, or caustic soda, NaOH, gives a dark brown precipitate of silver oxide, Ag20. 2 AgN03 + 2 KOH = Ag20 + H20 + 2 KN03. The precipitate is soluble in ammonia with formation of AgNHgOH. AgsO + 2 NH3 + H20 = 2 AgNH3OH. Ammonia gives the same precipitate, soluble of course in excess. 5. Sulphuretted hydrogen, H2S, gives a! black precipitate of silver sulphide, Ag9S, insoluble in dilute acids, except Itot dilute nitric acid. 6. When a silver salt is mixed with sodium carbonate, Na2C03, and heated on charcoal before the blowpipe, brilliant white malleable beads of silver are obtained. The silver salt is first converted into the carbonate, which is unstable, and readily breaks up into metallic silver, C02, and oxygen. 4 AgCl + 2 Na2C03 = 4 NaCl + 4 Ag + 2 C02 + 02. The beads of silver do not mark paper. Silver nitrate is the only common soluble salt of silver. QL. ANAL. C