Question

Which of the following chemical reaction that usually occurs in the crevice?

(a) M^++H2O=MOH

(b) M^++Cl^–=MCl(s)

(c) M^+Cl^–+H2O=MOH(aq)+H^+Cl^–

(d) 4OH^–=O2+2H2O+4e^–

I have been asked this question by my school teacher while I was bunking the class.

My doubt is from Eight Forms topic in division Eight Forms of Corrosion of Corrosion Engineering

Answer 1

Correct choice is (c) M^+Cl^–+H2O=MOH(aq)+H^+Cl^–

Explanation: As the metallic ion concentration increases in the crevice, the migration of chloride ions takes place to neutralize that. After that, metal chlorides undergo hydrolysis and results in the formation of insoluble metal hydroxide and free acid.