Question

In which of the following reactions, we observe the unaffected corrosion rate with the increase in temperature?

(a) 18Cr–8Ni in HNO3

(b) 18Cr-8Ni in H2SO4

(c) Ni in HCl

(d) Fe in HF

The question was asked in an interview for internship.

Question is taken from Effect of Temperature and Corrosive Concentration in chapter Corrosion Principles of Corrosion Engineering

Answer 1

The correct choice is (a) 18Cr–8Ni in HNO3

For explanation I would say: Stainless steel (18Cr–8Ni) in the HNO3 medium will have a negligible effect on the corrosion rate with the increase in temperature. It forms a stable oxide layer and avoids the exposure of a corrosive atmosphere to the metallic surface. It is stable up to very high temperatures.