Testing Procedure (Method of analysis) for Silver Compounds, Sodium Salts and Sulphates

Silver Compounds

Dissolve 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 Salts

A. 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 percent 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 of the substance under examination with 1M acetic acid and add a large excess of magnesium uranyl acetate solution; a yellow, crystalline precipitate is formed.

Sulfates

A. 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 sulfites and dithionites) but is decolorized by adding, dropwise, stannous chloride solution (distinction from iodates). Boil the mixture; no colored 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.

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