Question

You are provided with two containers made up of Copper and Aluminum. You are also provided with a solution of dil. $\mathrm{HCl}$, dil. ${\mathrm{HNO}}_3$, and ${\mathrm{H}}_2\mathrm{O}$. In which of the above containers, these solutions can be kept?

Answer 1

Reactivity series:

• The arrangement of metals in the descending order of their reactivities re known as the reactivity series of metals
• This is used to predict whether a metal can displace another in a single displacement reaction.
• It is also be used to find the reactivity of metals towards water and acids.
• The most reactive element is placed at the top and the least reactive element at the bottom.

Part 1: Reactivity of Copper with each of the solutions:

The chemicals should be stored in a container which is non-reactive to the specific chemicals.

Water and dil. Hydrochloric acid in Copper vessel:

• Copper will not react with dilute $\mathrm{HCl}$ because copper is present below hydrogen in the reactivity series. So, copper can not displace hydrogen form water and dilute acids.
• So, dilute Hydrochloric acid can be stored in a copper container.
• No reaction would take place between water and Copper, so water can be stored in a copper container.

dil. Nitric acid in Copper vessel:

• Nitric acid is a strong oxidizing agent. So, it oxidizes copper to copper nitrate.
• Copper will react with dilute Nitric acid in order to form Copper nitrate along with some side products. So dilute Nitric acid can be stored in a copper container.

$\underset{\mathrm{Copper}}{3\mathrm{Cu}\left(\mathrm{s}\right)}+\underset{\mathrm{Nitric}\mathrm{acid}}{8{\mathrm{HNO}}_3\left(\mathrm{aq}\right)}\to \underset{\mathrm{Copper}\mathrm{nitate}}{3\mathrm{Cu}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{aq}\right)}+\underset{\mathrm{Nitric}\mathrm{oxide}}{2\mathrm{NO}\left(\mathrm{g}\right)}+\underset{\mathrm{Water}}{4{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

Part 2: Reactivity of Aluminium with each of the solutions

dil. Hydrochloric acid in Aluminium vessel:

• Dilute Hydrochloric acid will react with Aluminium in order to form Aluminium trichloride along with Hydrogen gas. So, dilute Hydrochloric acid can be stored in an Aluminium container.
  $\underset{\mathrm{Aluminium}}{2\mathrm{Al}\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrochloric}\mathrm{acid}}{6\mathrm{HCl}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Aluminium}\mathrm{chloride}}{2{\mathrm{AlCl}}_3\left(\mathrm{aq}\right)}+\underset{\mathrm{Hydrogen}}{3{\mathrm{H}}_2\left(\mathrm{g}\right)}$

dil. Nitric acid in Aluminium vessel:

• In dilute nitric acid, Aluminium would form a thin layer of Aluminium oxide which will protect the Aluminium vessel from further reaction. So, dilute Nitric acid can be stored in an Aluminium vessel.

Water in Aluminium vessel:

• No reaction would take place between water and Aluminium, so water can be stored in an Aluminium container.
• However, Aluminium could react with hot water in order to form an Aluminium oxide,
  $\underset{\mathrm{Aluminium}}{2\mathrm{Al}\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Aluminium}\mathrm{oxide}}{{\mathrm{Al}}_2{\mathrm{O}}_3\left(\mathrm{aq}\right)}+\underset{\mathrm{Hydrogen}}{{\mathrm{H}}_2\left(\mathrm{g}\right)}$

Therefore, dilute $\mathrm{HCl}$ and ${\mathrm{H}}_2\mathrm{O}$ can be stored in the Copper container and dilute ${\mathrm{HNO}}_3$ can be stored in an Aluminium container.