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 presentAllows reaction to take placeOxygen and water are both necessary, as together they can be reduced to form hydroxide ions
Electrolyte presentIncreases rateAllows ions to move freely between the site of oxidation and the site of reduction
Impure ironIncreases rateImpurities may act as the cathode
Iron in contact with less active metalIncreases rateLess active metal serves as the cathode
Iron under mechanical stressIncreases rateIndividual iron atoms are less tightly bonded together and can more easily break away