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Anion tests
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Common ions Chloride Cl- Carbonate CO3- - Hydrogen Carbonate HCO3-
Sulfate SO4- - SO3- - Sulfite NO3- Nitrate PO4- - - Phosphate
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Chloride test Make a solution of the salt Add silver nitrate solution
If chloride it produces…… A white precipitate - + + - AgNO3 NaCl AgCl NaNO3 + + =
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Confirm chloride Take the white precipitate obtained earlier Add….
Ammonia solution If chloride…. The precipitate dissolves
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Nitrate ‘Brown ring test’ Make a solution of the salt
Add Iron sulfate solution Mix Add conc sulfuric acid This sinks to the bottom A brown ring forms At the top of the sulfuric acid layer
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Phosphate Make a solution of the salt Add Ammonium molybdate solution
Conc nitric acid If phosphate a Yellow precipitate forms
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Sulfate or sulfite BaSO4 BaSO3 Make a solution of the salt
Add barium chloride solution both sulfate and sulfite give….. A white precipitate - - + ++ + - - ++ - - Na2SO4 BaSO4 NaCl BaCl2 + = + BaCl2 Na2SO3 NaCl = BaSO3 + +
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Distinguish Sulfate or sulfite
Take the white precipitate obtained earlier Add dilute hydrochloric acid If the precipitate dissolves the salt was… Sulfite If it does not dissolve it is sulfate H2O BaSO3 HCl BaCl2 SO2 + + = + BaSO4 HCl = + No reaction
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Distinguish between sulfate and sulfite
Take the white precipitate obtained earlier Add dilute hydrochloric acid If the precipitate dissolves the salt was… Sulfite If it does not dissolve it is sulfate
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Carbonate or HydrogenCarbonate
Add hydrochloric acid to the solid Check for carbon dioxide gas using Lime water If it turns Milky It indicates the presence of carbonate or hydrogen carbonate
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Solubility of CO3- - and HCO3-
Carbonates are generally insoluble Except Sodium carbonate Na2CO3 Hydrogen carbonates are generally soluble
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Distinguish between carbonate and hydrogencarbonate
Make a solution of the salt Add a magnesium sulfate solution If you get a white precipitate it indicates Carbonate If no precipitate it indicates It indicates Hydrogen carbonate - - - - - - - - ++ + + ++ Na2SO4 MgSO4 Na2CO3 MgCO3 + + =
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Distinguish between carbonate and hydrogencarbonate
Make a solution of the salt Add a magnesium sulfate solution If you get a white precipitate it indicates Carbonate If no precipitate it indicates It indicates Hydrogen carbonate - - - - - - - ++ + + ++ Na2SO4 MgSO4 NaHCO3 MgHCO3 + + =
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Confirm hydrogencaronate
Boil the clear solution obtained If it is a Hydrogencarbonate….. A white precipitate now forms
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