-calcium, lead and barium sulphates Aqueous cations: Test Ion Result Add a few drops of dilute sodium Cu2+ Pale blue precipitate hydroxide solution. A precipitate will Fe2+ Green precipitate form. Fe3+ Red-Brown precipitate Al3+, Zn2+, White precipitate Ca2+ Divide the solutions into two equal Al3+ The precipitate dissolves again in volumes. To one, add double the sodium hydroxide solution giving volume of sodium hydroxide a colourless solution. solution. To the other, add double Zn2+ Precipitate dissolves in both the volume of ammonium solutions, giving a colourless hydroxide. solution. Ca2+ Dissolves in neither. NH4+ Take a small amount of the solid or Ammonia gas given off (it has a solution. Add a little dilute sodium strong sharp smell and turns red hydroxide solution and heat gently. litmus blue) Anions: Test Ion Result Take a small amount of the Carbonate Carbon dioxide gas is solid/solution. Add a little produced so there are dilute hydrochloric acid. bubbles and limewater goes milky Take a small amount of the Chloride White precipitate solution. Add an equal Iodide Yellow volume of dilute nitric acid. Then add silver nitrate solution. Silver halides are insoluble, so a precipitate forms. Take a small amount of the Nitrate Ammonia gas given off solution. Add a little sodium hydroxide solution. Add aluminium foil and heat gently. Take a small amount of the Sulphate White precipitate (barium solution. Add an equal sulphate)
-calcium, lead and barium sulphates Aqueous cations: Test Ion Result Add a few drops of dilute sodium hydroxide solution. A precipitate will form. Cu2+ Pale blue precipitate Fe2+ Green precipitate Fe3+ Red-Brown precipitate Al3+, Zn2+, Ca2+ White precipitate Divide the solutions into two equal volumes. To one, add double the volume of sodium hydroxide solution. To the other, add double the volume of ammonium hydroxide. Al3+ The precipitate dissolves again in sodium hydroxide solution giving a colourless solution. Zn2+ Precipitate dissolves in both solutions, giving a colourless solution. Ca2+ Dissolves in neither. Take a small amount of the solid or solution. Add a little dilute sodium hydroxide solution and heat gently. NH4+ Ammonia gas given off (it has a strong sharp smell and turns red litmus blue) Anions: Test Ion Result Take a small amount of the solid/solution. Add a little dilute hydrochloric acid. Carbonate Carbon dioxide gas is produced so there are bubbles and limewater goes milky Take a small amount of the solution. Add an equal volume of dilute nitric acid. Then add silver nitrate solution. Silver halides are insoluble, so a precipitate forms. Chloride White precipitate Iodide Yellow Take a small amount of the solution. Add a little sodium hydroxide solution. Add aluminium foil and heat gently. Nitrate Ammonia gas given off Take a small amount of the solution. Add an equal Sulphate White precipitate (barium sulphate)
chemistry-igcse-paper-6-study-guide.docx