Page 14 - NCERT Science Class 10 English Medium

2Pb(NO ) (s) Heat 2PbO(s) + 4NO (g) + O (g) (1.21)
→
3 2  2 2
(Lead nitrate) (Lead oxide) (Nitrogen (Oxygen)
dioxide)
Let us perform some more decomposition reactions as given in
Activities 1.7 and 1.8.

Activity 1.7
Activity 1.71.7
Activity 1.7
Activity
Activity 1.7
n 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 Figure 1.6
at both the electrodes. These bubbles displace water in the Electrolysis of water
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?

Activity 1.81.8
Activity 1.8
Activity
Activity 1.8
Activity 1.8
n Take about 2 g silver chloride in a china dish.
n What is its colour?
n Place this china dish in sunlight for some time
(Fig. 1.7).
n Observe the colour of the silver chloride after some
time.

Figure 1.7
You will see that white silver chloride turns grey in sunlight. This is Silver chloride turns grey
due to the decomposition of silver chloride into silver and chlorine by in sunlight to form silver
metal
light.
Sunlight
2AgCl(s)  → 2Ag(s) + Cl (g) (1.22)
2

Chemical Reactions and Equations 9 9 9 9 9

2024-25