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. 1.6.
n Connect these electrodes to a 6 volt
battery.
n Fill the mug with water such that the
electrodes are immersed. Add a few drops
of dilute sulphuric acid to the water.
n Take two test tubes filled with water and
invert them over the two carbon electrodes.
n Switch on the current and leave the
apparatus undisturbed for some time.
n You will observe the formation of bubbles
at both the electrodes. These bubbles displace water in the
test tubes.
n Is the volume of the gas collected the same in both the test tubes?
n Once the test tubes are filled with the respective gases, remove
them carefully.
n 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.
n What happens in each case?
n Which gas is present in each test tube?
Figure 1.6
Electrolysis of water
2Pb(NO3)2(s) ¾¾He¾at¾®2PbO(s) + 4NO2(g) + O2(g) (1.21)
(Lead nitrate) (Lead oxide) (Nitrogen (Oxygen)
dioxide)
Let us perform some more decomposition reactions as given in
Activities 1.7 and 1.8.