Question

On heating, lead nitrate forms oxides of nitrogen and lead. The oxides formed are _______
(A) ${{N}_{2}}O$, PbO
(B) $N{{O}_{2}}$, PbO
(C) NO, PbO
(D) NO, $Pb{{O}_{2}}$

Answer 1

. Think about what happens when lead nitrate is heated. Write the formula of lead nitrate. The question says oxides of nitrogen and lead are formed. Write a balanced chemical reaction of decomposition of lead oxide and determine the molecular formula of products formed to get the answer.

Complete step by step answer:
- When lead nitrate is heated, it breaks down into the following components:
Yellow colour lead (II) oxide (PbO)
Colourless gas of oxygen (${{O}_{2}}$) and
Brown colour nitrogen dioxide ($N{{O}_{2}}$).

- The chemical equation for the above reaction is,
$2Pb{{\left( N{{O}_{3}} \right)}_{2}}\to 2PbO+4N{{O}_{2}}+{{O}_{2}}$
- So, the correct answer to the question is option (B) PbO and $N{{O}_{2}}$

- Let us now look at the other options as well.
- Option (A) ${{N}_{2}}O$ and PbO. Here although the formation of PbO is possible, whereas ${{N}_{2}}O$ cannot be formed in the reaction.

- Option (C) NO and PbO. Here although the formation of PbO is possible, whereas NO cannot be formed in the reaction.

- Option (D) NO and $Pb{{O}_{2}}$. Here both NO and $Pb{{O}_{2}}$ are not formed in the reaction.
So, the correct answer is “Option B”.

Additional Information:
- In coarse, crystalline lead (II) nitrate, this reaction is accompanied by a physical process called decrepitation, whereby the gaseous products released during decomposition cause a sudden build-up of pressure within the crystals, which results in the crystals flying apart almost explosively, making a distinct crackling sound.
- Decrepitation is the noise produced when certain chemical compounds are heated, or it refers to the cracking, or breaking-up of lumps of limestone during heating. Such compounds include lead nitrate and calcine.
- PbO finds a lot of applications for humankind which involves the making of cathode ray tubes, in lead-based industrial glass and industrial ceramics, including computer components.
- $N{{O}_{2}}$ finds its application as a catalyst in some oxidation reactions, as an inhibitor to prevent the polymerization of acrylates during distillation, as an organic compound nitrating agent, as an oxidizing agent, as a rocket fuel, as a flour bleaching agent

Note: Remember decomposition of lead nitrate in the presence of heat results in a yellow coloured solid which is lead oxide, PbO, and a pungent smelling brown coloured gas which is nitrogen dioxide, $N{{O}_{2}}$. $N{{O}_{2}}$ is used as a rocket fuel and also as a catalyst in some oxidation reactions. PbO is used in the glass and ceramic industry.