Question

Give reason for the following: Concentrated Sodium hydroxide cannot be stored in Aluminium containers.

Answer 1

• Sodium hydroxide ($\mathbf{NaOH}$) cannot be stored in a vessel of Aluminium or Zinc because it results in the corrosion of the metal and the releases of Hydrogen gas. That is

$$\begin{gathered} \mathrm{Al}\left(\mathrm{s}\right)+\mathrm{NaOH}\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to {\mathrm{NaAlO}}_2\left(\mathrm{s}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right) \\ \mathrm{Aluminium}\mathrm{Sodium}\mathrm{Water}\mathrm{Sodium}\mathrm{Hydrogen} \\ \mathrm{hydroxide}\mathrm{aluminate} \end{gathered}$$

• Therefore, Sodium hydroxide is not stored in Aluminium containers.