Question

Give Reasons: Copper And Brass Utensils Should Be Tinned.

Answer 1

Corrosion:

• When metals are exposed to moist air, Metal Oxide is formed; this process is called corrosion.
• For example: When iron (Fe) is exposed to damp air, it interacts with oxygen to generate rust (${\mathrm{Fe}}_2{\mathrm{O}}_3.{\mathrm{xH}}_2\mathrm{O}$).

$\underset{\mathrm{Iron}}{4\mathrm{Fe}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{3{\mathrm{O}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Moisture}}{6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Rust}}{4\mathrm{Fe}{\left(\mathrm{OH}\right)}_3\left(\mathrm{s}\right)}$

Tinning:

• Copper and brass materials, like iron, corrode, resulting in a greenish coating on the surface.
• Tin is lightly deposited on the surface of copper and brass materials to avoid this. This is known as tinning.
• Tinplate is created by cold rolling steel or iron, cleaning to erase any scale, heating to eliminate any strain hardening, and then covering it with a thin layer of tin.
• This procedure is often used to prevent corrosion and to avoid oxidation on the ends of stranded wire used as electrical conductors.
• A few examples of tinning are cheap pots, pans, and other hollowware.

Thus, to avoid corrosion, copper and brass materials should be tinned.