Conditions under rusting occurs

Shipwrecks and Salvage‎ > ‎2. Corrosion of Iron‎ >

Use available evidence to analyse and explain the conditions under which rusting occurs

Condition: Effect on Reaction: Explanation:
Oxygen and water present Allows reaction to take place Oxygen and water are both necessary, as together they can be reduced to form hydroxide ions
Electrolyte present Increases rate Allows ions to move freely between the site of oxidation and the site of reduction
Impure iron Increases rate Impurities may act as the cathode
Iron in contact with less active metal Increases rate Less active metal serves as the cathode
Iron under mechanical stress Increases rate Individual iron atoms are less tightly bonded together and can more easily break away