Salts

Tests to Distinguish Iron(II) and Iron(III) ions The presence of Fe2+ ion and Fe3+ ion in a salt can be confirmed by using solution of potassium hexacyanoferrate (II), solution of potassium hexacyanoferrate (III) and potassium thiocyanate. Table below shows the observation of the tests. Reagent Observation Ion presents Solution of potassium hexacyanoferrate (II) Light blue precipitate Fe2+ Dark Blue precipitate Fe3+ … Read more

Test with Iodide Ions Iodide ions will form precipitate with lead(II) ions and copper(II) ions. However, in SPM you only need to know the reaction between lead(II) ions and iodide ions. The yellow precipitate formed will dissolve in hot water.Pb2+ + 2I– → PbI2 KI Na+ – Ca2+ – Mg2+ – Al3+ – Zn2+ – Pb2+ Yellow … Read more

Test with Carbonate Ions All ions, except sodium ions and ammonium ions will form precipitate with carbonate. This is because sodium carbonate and ammonium carbonate are soluble in water. Na2CO3 Na+ – Ca2+ White precipitate. Mg2+ White precipitate. Al3+ White precipitate. Zn2+ White precipitate. Pb2+ White precipitate. Fe2+ Green precipitate. Fe3+ Brown precipitate. Cu2+ Blue … Read more

Test with Sulphate Ions Out of the 10 cations, only calcium ions and lead(II) ions will form a precipitate with sulphate ions. This is because both calcium sulphate and lead(II) sulphate are insoluble in water. The chemical reaction is a double decomposition reaction.Pb2+ + SO42- → PbSO4Ca2+ + SO42- → CaSO4 H2SO4 or Na2SO4 Na+ – Ca2+ White precipitate. Mg2+ – … Read more

Test with Chloride Ions Out of the 10 cations, only lead(II) ions will form a precipitate with chloride ions. This is because lead(II) chloride is insoluble in water. The chemical reaction is a double decomposition reaction.Pb2+ + 2Cl– → PbCl2 Lead(II) chloride will dissolve in hot water. HCl or NaCl Na+ – Ca2+ – Mg2+ – … Read more

Test with Sodium Hydroxide and Ammonia Solution Cations can be identified by their reaction with aqueous sodium hydroxide and aqueous ammonia. Sodium hydroxide and aqueous ammonia produce hydroxide ion which will react with most anion to form precipitate.NaOH + H2O → Na+ + 2OH– + H+   NH3 + H2O → NH4+ + OH–  Different … Read more

Identifying Anions – Carbonate In form 4 chapter 7, Acids and Bases, you should have learned that the carbonate salts react with acid produce carbon dioxide and water. This chemical property of carbonate is used to test the presence of carbonate in a salt.CO32– + 2H+ → H2O + CO2 During the test, some dilute hydrochloric … Read more

Heating Effect on Carbonate Salts All carbonates salts except potassium carbonate and sodium carbonate can be decomposed by heat to produce carbon dioxide gas.  Table below shows the effect of heating on metal carbonate. Carbonate Salt Equation of The Reaction Potassium carbonate Sodium carbonate  Will not decompose by heat Calcium carbonate Magnesium carbonateAluminium carbonateZinc carbonateIron … Read more

Qualitative Analysis Identification of Ions There are 10 cations and 4 anions to be studied in our syllabus: Cation Sodium Na+ Iron (II) Fe2+ Calcium Ca2+ Iron (III) Fe3+ Magnesium Mg2+ Lead(II) Pb2+ Aluminium Al3+ Copper (II) Cu2+ Zinc Zn2+ Ammonium NH4+ Anion Chloride ion Cl– sulphate ion SO42- nitrate ion NO3– carbonate ion CO3– … Read more

Colour of Ions Salt or metal oxide Solid Aqueous solution Salt of Sodium, Calcium, Magnesium, Aluminium, zinc, Lead, ammonium  White  Colourless Salt of Chloride, sulphate, nitrate, carbonate  White  Colourless Salt of Copper(II).- Copper(II) Carbonate Green – Copper(II) sulphate, Copper(II) nitrate, Copper(II) chloride Blue Blue Copper(II) oxide Black – Salt of Iron (II):Iron(II) sulphate; Iron(II) nitrate; … Read more