Question

___________ gas is evolved on heating lead nitrate and ____________ gas is evolved on heating sodium nitrate.

• A. NO₂ (Nitrogen dioxide)
• B. O₂ (Oxygen)

Answer 1

• When lead nitrate($\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2$) is heated it decomposes to form lead oxide, nitrogen dioxide, and oxygen.
• Thus, lead nitrate on decomposition gives lead oxide, nitrogen dioxide, and oxygen.
• Lead nitrate, on heating strongly in a dry test tube, produces lead oxide($\mathrm{PbO}$), nitrogen dioxide (${\mathrm{NO}}_2$ ), and oxygen (${\mathrm{O}}_2$).
• When lead(II) nitrate is heated, it breaks down or decomposes into yellow color lead (II) oxide, colorless gas of oxygen, and brown color nitrogen dioxide.

Chemical reaction:

$$\begin{gathered} 2\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_{2\left(\mathrm{s}\right)}\stackrel{∆}{\to }2{\mathrm{PbO}}_{\left(\mathrm{s}\right)}+4{\mathrm{NO}}_{2\left(\mathrm{g}\right)}+{\mathrm{O}}_{2\left(\mathrm{g}\right)} \\ \mathrm{lead}\mathrm{nitrate}\mathrm{lead}\mathrm{oxide}\mathrm{nitrogen}\mathrm{dioxide}\mathrm{oxygen} \end{gathered}$$

• Sodium nitrate upon heating decomposes to produce sodium nitrite and colorless and odorless oxygen gas.
• On heating sodium nitrate it undergoes a decomposition reaction.

Chemical reaction:

$$\begin{gathered} 2{\mathrm{NaNO}}_{3\left(\mathrm{s}\right)}\stackrel{∆}{\to }2{\mathrm{NaNO}}_{2\left(\mathrm{s}\right)}+{\mathrm{O}}_{2\left(\mathrm{g}\right)} \\ \mathrm{Sodium}\mathrm{nitrate}\mathrm{sodium}\mathrm{nitrite}\mathrm{oxygen} \end{gathered}$$

Therefore, nitrogen dioxide gas evolved on heating lead nitrate, and oxygen gas evolved on heating sodium nitrate.