When lead nitrate is heated, brown fumes are evolved. Which gas causes these fumes, and what type of reaction is this?
Answer and explanation
Correct answer: Nitrogen dioxide and thermal decomposition
On heating, lead nitrate decomposes to form lead oxide, nitrogen dioxide, and oxygen: \(2\mathrm{Pb(NO_3)_2} \xrightarrow{\Delta} 2\mathrm{PbO} + 4\mathrm{NO_2} + \mathrm{O_2}\). The brown fumes are nitrogen dioxide, \(\mathrm{NO_2}\). Since one compound breaks down into simpler substances on heating, this is a thermal decomposition reaction, not a combination reaction.
Frequently asked questions
What is the correct answer to this question?
Nitrogen dioxide and thermal decomposition
Why is this the correct answer?
On heating, lead nitrate decomposes to form lead oxide, nitrogen dioxide, and oxygen: \(2\mathrm{Pb(NO_3)_2} \xrightarrow{\Delta} 2\mathrm{PbO} + 4\mathrm{NO_2} + \mathrm{O_2}\). The brown fumes are nitrogen dioxide, \(\mathrm{NO_2}\). Since one compound breaks down into simpler substances on heating, this is a thermal decomposition reaction, not a combination reaction.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Chemical Reactions and Equations.
