![]() (One solution is to simulate hard water conditions.) If you live in a soft water area there will probably be no cloudiness. However, with tap water a cloudiness gradually develops if the water is from a hard water area since carbonates, sulphates or hydrogen carbonates may be present. The addition of deionised water to lead nitrate gives no cloudiness. The fact that lead forms insoluble compounds is used as a basis for indicating the presence of anions in water. The iodide is an intense yellow colour, the chromate(VI) is also yellow and both could be used as pigments except for the fact that lead compounds are toxic. The addition of solutions of each of the anions produces precipitates, which indicates that in general lead compounds are insoluble. Teaching notes and expected observations Part 1 What explanations can you give for your observations? What is the main disadvantage of using these compounds as pigments?.Which of the lead compounds observed appear to be good pigments?. ![]() Add one drop of deionised water and one drop of tap water to the appropriate boxes.With the worksheet still covered, put one drop of lead nitrate solution into each box of table 2.Part 2: adding deionised water and tap water to lead nitrate solution Add one drop of each of the solutions containing the anions indicated to the appropriate box.Put one drop of lead nitrate solution in each box of table 1.Cover the worksheet with a clear plastic sheet.Procedure Part 1: adding different anions to lead nitrate solution ![]()
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