Activity 1.8

Activity . Take about g silver chloride in a china dish. What is its colour? Place this china dish in sunlight for some time (Fig. . ). Observe the colour of the silver chloride after some time. Figure . Silver chloride turns grey in sunlight to form silver metal You will see that white silver chloride turns grey in sunlight. This is due to the decomposition of silver chloride into silver and chlorine by light. 2AgCl(s) Sunlight  2Ag(s) + Cl (g) ( . ) Take a plastic mug. Drill two holes at its base and fit rubber stoppers in these holes. Insert carbon electrodes in these rubber stoppers as shown in Fig. . . Connect these electrodes to a volt battery. Fill the mug with water such that the electrodes are immersed. Add a few drops of dilute sulphuric acid to the water. Take two test tubes filled with water and invert them over the two carbon electrodes. Switch on the current and leave the apparatus undisturbed for some time. You will observe the formation of bubbles at both the electrodes. These bubbles displace water in the test tubes. Is the volume of the gas collected the same in both the test tubes? Once the test tubes are filled with the respective gases, remove them carefully. Test these gases one by one by bringing a burning candle close to the mouth of the test tubes. CAUTION: This step must be performed carefully by the teacher. What happens in each case? Which gas is present in each test tube? Figure . Electrolysis of water 2Pb(NO ) (s) Heat  2PbO(s) 4NO (g) + O (g) ( . ) (Lead nitrate) (Lead oxide) (Nitrogen (Oxygen) dioxide) Let us perform some more decomposition reactions as given in Activities . and . . Figure . (a) Iron nails dipped in copper sulphate solution