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Let us do an activity to understand the process of decomposition.
Activity \(1.6\): Decomposition of lead nitrate.
Materials required:
-Lead nitrate powder \(2\)
-Boiling tube
-Tongs and
Experimental procedure:
Step 1: Take \(2\) g white lead nitrate powder in a boiling tube.
Step 2: Heat the boiling tube over the flame of the burner using the tong.
Step 3: Observe what happens when you are heating lead nitrate in the boiling tube.
  • Emission of brown fumes (brown fumes coming out of the test tube).
  • The white lead nitrate, after heating, converted into a brown powder.
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Decomposition of lead nitrate
The brown fumes coming out of the boiling tube are nitrogen dioxide.
The brown powder formed after heating the white lead nitrate is lead oxide.
Decomposition reaction:
\(2Pb(NO_3)_2\)(s) Heat \(2PbO\)(s) + \(4NO_2\)(g) + \(O_2\)(g)
(Lead nitrate)               (Lead oxide) + (Nitrogen dioxide) + (Oxygen)
In this reaction, you can notice that a single reactant breaks down to give simpler products. This is known as a decomposition reaction. Here lead nitrate decomposes into lead oxide, nitrogen dioxide, and oxygen.