Question

List the factor affecting the rate of corrosion.

Answer 1

Factors affecting the rate of corrosion-

The rate of corrosion is affected by the below-mentioned factors.

Electropositive nature of metals -

• More electropositive metals are more reactive and they get corroded faster.
• Example - Iron gets corroded faster than silver because iron is more electropositive than silver.

Purity of metals-

• Pure metals do not corrode.
• The presence of impurities in metals tends to increase the rate of corrosion.

Presence of reactive gases in the air-

• Gases such as oxides of sulphur $({\mathrm{SO}}_2,{\mathrm{SO}}_3)$, oxides of nitrogen$\left({\mathrm{NO}}_{\mathrm{x}}\right)$, and carbon dioxide $\left({\mathrm{CO}}_2\right)$ in the presence of moisture produce acids and accelerate the rate of corrosion.

Presence of electrolytes in water -

• The presence of an electrolyte such as sodium chloride $\left(\mathrm{NaCl}\right)$ in water increases the rate of corrosion.
• Example - Iron corrodes faster in seawater than in distilled water because seawater contains many dissolved electrolytes.

Temperature -

• As the temperature increases within a certain limit, the rate of corrosion also increases.