The steel hull of a ship is in contact with sea water.
Blocks of zinc are bolted onto the steel hull below the water line. The zinc blocks must be replaced every few years.
State the two substances that must be present for iron to rust.
Explain how the zinc blocks stop the steel hull from rusting.
Explain why the zinc blocks must be replaced every few years.
Write the half equation for the reaction of the zinc atoms in the blocks.
Food cans are made of steel coated with a thin layer of tin. Tin is less reactive than iron.
Buckets are often made of galvanised steel, which is steel coated with zinc.
Explain why a tin-coated can rusts if its coating is scratched, but a galvanised bucket does not.
61 exam-style questions on OCR GCSE Chemistry 6.1 Improving processes and products, covering 6.1.1 Extracting metals industrially and by electrolysis, 6.1.2 Life cycle assessment and recycling, 6.1.3 Biological methods of metal extraction, 6.1.4 The Haber process and the production of fertilisers, 6.1.5 Alloys and their uses, 6.1.6 Corrosion and its prevention, 6.1.7 Comparing and selecting materials, and 6.1.8 Industrial conditions, rate and position of equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.