Question

Explain how areas of cathode and anode affect the rate of corrosion.

Answer 1

Relative areas of the Anodic and Cathodic Parts:
When 2 dissimilar metals are in contact, the corrosion of the anodic part is directly proportional to the ratio of areas of the cathodic part and anodic part. Thus, mathematically,

`"Rate of Corrosion"  alpha "Acathode"/"Aanode"`

This is because when the cathode area is larger than the anodic area, then the demand for electrons by the cathodic area will be more which can only be met by the anodic area by undergoing faster corrosion. Thus, smaller the area of the anode, faster is the rate of corrosion. Thus,

`"Corrosion"  alpha 1/"Anode Area"`