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.

Answer 1

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:

1. The emission of brown fumes of NO₂ after thermal decomposition of Pb(NO₃)₂.
2. The colourless compound Pb(NO₃)₂ forms a yellow compound PbO and brown fumes of NO₂ gas.

(c)

\[\ce{\underset{(Lead nitrate)(solid)}{2Pb(NO3)2_{(s)}} ->[Heat]\underset{(Lead oxide)(solid)}{2PbO_{(s)}} + \underset{(Nitrogen dioxide)(gas)}{4NO2_{(g)}} + \underset{(Oxygen)(gas)}{O2_{(g)}}}\]