Question

Why don't we use $\mathrm{HCl}$ to clean the statue of liberty?

Answer 1

Oxidation:

• The process brought on by coming into touch with oxygen molecules is known as oxidation.
• These materials can be non-metals like live tissues or metals.
• Technically speaking, oxidation is the loss of one electron during the phase of interaction between two or more atoms.

In case of Statue of Liberty:

• The statue of liberty is made up of Copper and it forms the Copper oxide$\left(\mathrm{CuO}\right)$ by reacting with the oxygen available in the air.
• $\underset{\left(\hspace{0.17em}\mathrm{Copper}\right)}{2\mathrm{Cu}\left(\mathrm{s}\right)}+\underset{\left(\mathrm{Oxygen}\right)}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\left(\mathrm{Copper}\mathrm{oxide}\right)}{2\mathrm{CuO}\left(\mathrm{s}\right)}$
• When $\mathrm{HCl}$ is used to clean the statue, it removes the protective copper oxide and exposes the copper beneath to further oxidation.
• $\underset{\left(\mathrm{Copper}\mathrm{oxide}\right)}{\mathrm{CuO}\left(\mathrm{s}\right)}+\underset{\left(\mathrm{Copper}\mathrm{Chloride}\right)}{\mathrm{HCl}\left(\mathrm{aq}\right)}\to \underset{\left(\mathrm{Copper}\mathrm{chloride}\right)}{{\mathrm{CuCl}}_2\left(\mathrm{s}\right)}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$
• If the statue was cleaned on a regular basis, it would eventually vanish.