Question

Name a white nitrate which on heating leaves a compound residue at ordinary temperature.

Answer 1

• Lead nitrate(Pb(NO₃)₂) is a white color nitrate.
• This nitrate upon heating produces lead monoxide(PbO) residue which is yellow, a reddish-brown gas named nitrogen dioxide(NO₂), and liberates oxygen gas(O₂).
• $\underset{\mathrm{Lead}\mathrm{Nitrate}}{2\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right)}\stackrel{\mathrm{heat}}{\to }\underset{\mathrm{Lead}\mathrm{Oxide}}{2\mathrm{PbO}\left(\mathrm{s}\right)}+\underset{\mathrm{Nitrogen}\mathrm{dioxide}}{4{\mathrm{NO}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}$
• It is a type of decomposition reaction.
• Decomposition reaction: In this type of reaction a chemical substance will be decomposed into two or more two substances.
• The new substance forms have completely different properties than their initial.

Therefore, Lead nitrate(Pb(NO₃)₂) is a white nitrate that on heating leaves a compound residue at ordinary temperature.