Why does corrosion accelerate in the presence of an electrolyte, and which mitigation approach is commonly used?

• A. The electrolyte conducts ions and facilitates electrochemical reactions; mitigation includes coatings, inhibitors, cathodic protection, and passivation.
• B. It increases solution viscosity, reducing diffusion; mitigation includes increasing electrolyte concentration.
• C. It directly raises metal potential without reactions; mitigation is to increase temperature.
• D. It forms a protective oxide instantly; mitigation is to remove oxide coatings.

Answer: (B)

The main idea is that corrosion in metals exposed to a liquid electrolyte happens because the electrolyte allows ions to move and charge to be transferred at the metal surface. This ion transport enables the electrochemical reactions that dissolve metal: metal atoms oxidize at the surface, releasing electrons, while ions or water in the solution gain those electrons at the cathodic sites. With the electrolyte present, these redox processes proceed readily, accelerating material loss.

Mitigation methods focus on interrupting this electrochemical cycle or protecting the surface. Coatings physically separate the metal from the electrolyte, inhibitors adsorb onto the surface to slow charge transfer, cathodic protection shifts the metal’s potential so it cannot oxidize easily (using a sacrificial anode or an external current), and passivation encourages the growth of a stable, protective oxide film that resists further reaction.

The other options miss the core idea: increasing viscosity would slow ion movement and diffusion, not speed corrosion; boosting electrolyte concentration generally increases conductivity and can raise corrosion rates rather than mitigate them; raising temperature typically accelerates reactions rather than reduce them; and removing oxide coatings would usually remove protection, not provide mitigation.