Testing And Identifying Anions

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Testing And Identifying Anions

  1. 1. Testing and Identifying Halide Ions Aim:To identify the conclusive chemical tests for Halide ions.
  2. 2. Chloride Cl -1 ;Bromide Br -1 ;Iodide I -1 <ul><li>Add about 2ml of aqueous chloride to a test tube </li></ul><ul><li>Add an equal volume of dilute HNO 3 </li></ul><ul><li>Add a few drops of silver (I) nitrate to the tube </li></ul><ul><li>Pour half of the contents of the tube into a clean test tube </li></ul><ul><li>To the 1 st tube add dilute ammonia until no further change </li></ul><ul><li>To the second tube add CONC AMMONIA until there is no further change – Do this in a fume cupborad </li></ul><ul><li>Repeat with aqueous solutions of bromide and iodide </li></ul>
  3. 3. Results Table I -1 Br -1 Cl -1 Action of conc NH 3 on product Action of dilute NH 3 on product HNO 3 then AgNO 3 Halide Ion
  4. 4. Results Table I -1 Br -1 White ppt dissolves White ppt Cl -1 Action of conc NH 3 on product Action of dilute NH 3 on product HNO 3 then AgNO 3 Halide Ion
  5. 5. Results Table I -1 Br -1 White ppt dissolves White ppt dissolves White ppt Cl -1 Action of conc NH 3 on product Action of dilute NH 3 on product HNO 3 then AgNO 3 Halide Ion
  6. 6. Results Table I -1 Cream ppt Br -1 White ppt dissolves White ppt Cl -1 Action of conc NH 3 on product Action of dilute NH 3 on product HNO 3 then AgNO 3 Halide Ion
  7. 7. Results Table I -1 Cream ppt dissolves No reaction Cream ppt Br -1 White ppt dissolves White ppt Cl -1 Action of conc NH 3 on product Action of dilute NH 3 on product HNO 3 then AgNO 3 Halide Ion
  8. 8. Results Table insoluble Insoluble Yellow ppt I -1 Cream ppt dissolves Insoluble Cream ppt Br -1 White ppt dissolves White ppt Cl -1 Action of conc NH 3 on product Action of dilute NH 3 on product HNO 3 then AgNO 3 Halide Ion
  9. 9. Ionic Equations for the reaction <ul><li>Sodium chloride + Silver nitrate </li></ul><ul><li>NaCl + AgNO 3 </li></ul><ul><li>Repeat for Sodium Bromide and Silver iodide as above </li></ul>
  10. 10. Sulphate SO 4 2- and Sulphite SO 3 2- Place 2ml of aqueous sulphate in a test tube. Add a few drops of barium chloride Add 1ml of HCl Dilute and shake the mixture vigorously Leave the tube to stand Repeat the experiment with a sample of aqueous sulphite – do in fume cup board, Test the gas evolved with acidified dichromate paper
  11. 11. Results Table SO 3 2- SO 4 2- Action of BaCl 2 followed by HCl Anions
  12. 12. Results Table Gas evolved with pungent odour – SO 2.. It turns acid dichromate paper from orange to green ( test for SO 2 ) SO 3 2- White ppt of BaSO 4 that does not redissolve in acid SO 4 2- Action of BaCl 2 followed by HCl Anions
  13. 13. Carbonate CO 3 2- and Hydrogen Carbonate HCO 3 -1 Add 1 ml of sodium carbonate to a test tube – add a few drops of HCl Repeat the experiment with aqueous potassium hydrogen carbonate Record the results in the table Add a few drops of Barium chloride
  14. 14. Results HCO 3 -1 CO 3 2- Reaction with HCl followed by Barium chloride Anion
  15. 15. Results Gas evolved – CO 2 No ppt formed HCO 3 -1 Gas evolved – CO 2 White ppt formed CO 3 2- Reaction with HCl followed by Barium chloride Anion
  16. 16. Nitrate ion NO 3 -1 Place together in a test tube a small amount of sodium nitrate (V) and a piece of Al foil. Add about 5ml of aqueous sodium hydroxide solution If no reaction takes place – carefully warn the tube in a water bath Test the gas evolved using damp red litmus paper
  17. 17. Results table Pungent gas evolved. Turns red litmus blue – Alkaline gas – Ammonia. Formed by the reduction of the nitrate ion. NO 3 -1 Observation Ion
  18. 18. Summary of results Nitrate Hydrogen carbonate Carbonate Sulphite Sulphate Iodide Bromide Chloride Result Test Formula Name of ion
  19. 19. Summary of results NO 3 -1 Nitrate HCO 3 -1 Hydrogen carbonate CO 3 2- Carbonate SO 3 -1 Sulphite (VII) SO 4 2- Sulphate (IV) I -1 Iodide Br -1 Bromide Cl -1 Chloride Result Test Formula Name of ion
  20. 20. Summary of results NO 3 -1 Nitrate HCO 3 -1 Hydrogen carbonate CO 3 2- Carbonate SO 3 -1 Sulphite (VII) SO 4 2- Sulphate (IV) Yellow ppt of AgI insoluble in excess NH 3 Acidified silver nitrate Solubility with ammonia I -1 Iodide Cream ppt of AgBr soluble in conc NH 3 Acidified silver nitrate Solubility with ammonia Br -1 Bromide White ppt of AgCl soluble in dil NH 3 Acidified silver nitrate Solubility with ammonia Cl -1 Chloride Result Test Formula Name of ion
  21. 21. Summary of results Gas evolved SO2.Test with dichromate paper turning from orange to green, As above SO 3 -1 Sulphite (VII) White ppt of BaSO 4 insoluble in acid Solution of barium chloride or nitrate.If ppt forms add dil HCl SO 4 2- Sulphate (IV) Yellow ppt of AgI insoluble in excess NH 3 Acidified silver nitrate Solubility with ammonia I -1 Iodide Cream ppt of AgBr soluble in conc NH 3 Acidified silver nitrate Solubility with ammonia Br -1 Bromide White ppt of AgCl soluble in dil NH 3 Acidified silver nitrate Solubility with ammonia Cl -1 Chloride Result Test Formula Name of ion
  22. 22. Summary of results(2) NO 3 -1 Nitrate HCO 3 -1 Hydrogen carbonate CO 3 2- Carbonate Result Test Formula Name of ion
  23. 23. Summary of results(2) NO 3 -1 Nitrate Dilute HCl followed by BaCl 2 HCO 3 -1 Hydrogen carbonate Dilute HCl followed by BaCl 2 CO 3 2- Carbonate Result Test Formula Name of ion
  24. 24. Summary of results(2) NO 3 -1 Nitrate Gas evolved No ppt. Dilute HCl followed by BaCl 2 HCO 3 -1 Hydrogen carbonate White ppt of BaCO 3 formed and gas evolved Dilute HCl followed by BaCl 2 CO 3 2- Carbonate Result Test Formula Name of ion
  25. 25. Summary of results(2) Add Al and dil NaOH NO 3 -1 Nitrate Gas evolved No ppt. Dilute HCl followed by BaCl 2 HCO 3 -1 Hydrogen carbonate White ppt of BaCO 3 formed and gas evolved Dilute HCl followed by BaCl 2 CO 3 2- Carbonate Result Test Formula Name of ion
  26. 26. Summary of results(2) Gas evolved – turns red litmus blue – alkaline gas – NH 3 from the reduction of NO2 Add Al and dil NaOH NO 3 -1 Nitrate Gas evolved No ppt. Dilute HCl followed by BaCl 2 HCO 3 -1 Hydrogen carbonate White ppt of BaCO 3 formed and gas evolved Dilute HCl followed by BaCl 2 CO 3 2- Carbonate Result Test Formula Name of ion
  27. 27. Name the Salt <ul><li>An unknown salt is dissolved in distilled water to make an aqueous solution. Sodium hydroxide is added to the solution and a green precipitate is formed that dissolves in sodium hydroxide to form a dark green solution. </li></ul><ul><li>When HCl is added to the solid a gas is evolved. When barium chloride is added to the solution a white ppt is formed </li></ul><ul><li>Name the salt </li></ul><ul><li>Write the chemical formula for this chemical </li></ul>Chromium (III) Carbonate Cr 2 (CO 3 ) 3

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