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Question
(a) Design an activity to demonstrate the decomposition reaction of lead nitrate.
(b) Draw labelled diagram of the experimental set-up. List two main observations.
(c) Write balanced chemical equation for the reaction stating the physical state of the reactant and the products.
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Solution
Activity to demonstrate the decomposition reaction of lead nitrate Pb(NO3)2
(a)
- Take about 2g of lead nitrate powder in a boiling tube.
- Hold the boiling tube with a pair of tongs and heat it over a flame, as shown in the figure.
- What do you observe? Note down the change, if any.
(b)
Two main observations:
- The emission of brown fumes of NO2 after thermal decomposition of Pb(NO3)2.
- The colourless compound Pb(NO3)2 forms a yellow compound PbO and brown fumes of NO2 gas.
(c)
\[\ce{\underset{(Lead nitrate)(solid)}{2Pb(NO3)2_{(s)}} ->[Heat]\underset{(Lead oxide)(solid)}{2PbO_{(s)}} + \underset{(Nitrogen dioxide)(gas)}{4NO2_{(g)}} + \underset{(Oxygen)(gas)}{O2_{(g)}}}\]
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