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Description
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A fine, heavy, white powder, free from gritty particles; odourless.
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Solubility
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Very slightly soluble in acids and in solution of alkali hydroxides, practically insoluble in water and in organic solvents
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Identification
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-
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Identification 'A'
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It should gives the reactions of sulphates
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Identification 'B'
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A white precipitate should formed which should be insoluble in dilute sodium hydroxide solution
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Acidity or alkalinity
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Not more than 0.5 ml of either 0.01M hydrochloric acid or 0.01 M sodium hydroxide should be required to change the colour of the solution
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Arsenic
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NMT 2 ppm
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Loss on ignition
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NMT 2.5%
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Phosphate
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No yellow precipitate should formed
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Sulphide
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The paper should not darken
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Acid soluble substances
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NMT 0.3%
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Soluble barium salts
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No turbidity should be produced
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