This document describes the double decomposition method for forming insoluble salts. It involves mixing two aqueous solutions containing different metal ions that exchange to form an insoluble salt precipitate. Specifically, it provides the example of mixing lead (II) nitrate and potassium iodide solutions to form lead (I) iodide precipitate. The procedure involves mixing the solutions, filtering out the precipitate, washing it with water, and drying to obtain pure salt crystals.

1. CONTENT INTRODUCTION METHOD PROCEDURE INSOLUBLE SALT

2. The INSOLUBLE SALT is one of salt that can not dissolve in water at room temperature INSOLUBLE SALT Video Clip:Insoluble Salt

3. The examples of insoluble salt: Stalactite Pearl Coral

4. DOUBLE DECOMPOSITION METHOD METHOD In double decomposition reaction, ions from the two different aqueous solution are exchangeable to form one of new compound which is not soluble in water. Solution A: contain the metal ion (cation,M + ) + Solution B: contain the non-metal ion (anion,X - ) Insoluble Salt Precipitate MX

5. CONTINUE…. In this method, requires two solution:

6. DOUBLE DECOMPOSITION METHOD For example, plumbum (II) chloride, PbCl 2 is one of the insoluble salt. Pb(NO 3 ) 2 + 2 KCl PbCl 2 + 2 KNO 3 Pb 2+ 2 Cl - + PbCl 2 CONTINUE….

7. DOUBLE DECOMPOSITION METHOD CHEMICAL EQUATION Ca (NO 3 ) 2 Ca + 2NO 3 - Na 2 SO 4 2Na + SO 4 2+ + Ionic Equation: Ca 2+ + SO 4 2+ CaSO 4 Ca(NO 3 ) 2 Na 2 S0 4 CaSO 4 2NaNO 3 + +

8. PROCEDURE OF PRECIPITATION REACTION Mix two solution Filtration Wash Dry Pure salt crystal Preparation of PbI 2

9. ACTIVITY 8.7 AIM : TO PREPARE INSOLUBLE SALT BY USING PRECIPITATION REACTION

10. MATERIALS : 1 MOL DM -3 LEAD (II) NITRATE SOLUTION, 1 MOL DM -3 POTASSIUM IODIDE SOLUTION, 1 MOL DM -3 BARIUM NITRATE AND 1 MOL DM -3 POTASSIUM SULPHATE APPARATUS : 250 CM3 BEAKER, GLASS ROD, FILTER FUNNEL AND FILTER PAPER

11. Add 50 cm3 of potassium iodide solution to 50 cm3 of lead (II) nitrate solution stir with the glass rode Yellow precipitate occur

12. Filter the mixture after the precipitate occur

13. Wash the precipitate of salt with deionized water

14. Dry the precipitate

15. Pure salt crystal formed

16. ACTIVITY