Silver CompoundsDissolve 10 mg of the substance under examination in 10 ml of water or use 10 ml of the prescribed solution. Add 0.3 ml of dilute hydrochloric acid; a curdy white precipitate, soluble in dilute ammonia solution, is produced. Add potassium iodide solution; a yellow precipitate, soluble in nitric acid, is produced.
Sodium SaltsA. Dissolve 0.1 g of the substance under examination in 2 ml of water or use 2 ml of the prescribed solution. Add 2 ml of a 15 per cent w/v solution of potassium carbonate and heat to boiling; no precipitate is produced. Add 4 ml of a freshly prepared potassium antimonate solution and heat to boiling.
Allow to cool in ice and if necessary scratch the inside of the test-tube with a glass rod; a dense, white precipitate is formed.
B. Acidify a solution ofthe substance under examination with 1M acetic acid and add a large excess of magnesium uranyl acetate solution; a yellow, crystalline precipitate is formed.
SulphatesA. Dissolve about 50 mg of the substance under examination in 5 ml of water or use 5 ml of the prescribed solution. Add 1 ml of dilute hydrochloric acid and 1 ml of barium chloride solution; a white precipitate is formed.
B. Add 0.1 ml of iodine solution to the suspension obtained in test A; the suspension remains yellow (distinction from sulphites and dithionites) but is decolorised by adding, dropwise, stannous chloride solution (distinction from iodates). Boil the mixture; no coloured precipitate is formed (distinction from selenates and tungstates).
C. Dissolve about 50 mg of the substance under examination in 5 ml of water or use 5 ml of the prescribed solution. Add 2 ml of lead acetate solution; a white precipitate, soluble in ammonium acetate solution and in sodium hydroxide solution, is produced.
Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
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