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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.
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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