An engineer investigated the corrosion of buried steel (iron) gas pipelines under two different conditions over a period of six months.
The observations are recorded in the table below:
| Pipeline | Setup | Observation after six months |
|---|---|---|
| Pipeline X | Steel pipe connected to a block of magnesium | The magnesium block has significantly corroded and decreased in mass, but the steel pipe remains undamaged. |
| Pipeline Y | Steel pipe connected to a block of copper | The copper block is completely unchanged, but the steel pipe has heavily rusted. |
Explain these observations.
97 exam-style questions on Edexcel GCSE Chemistry 6.1 Transition metals, alloys and corrosion, covering 6.1.1 Properties of transition metals, 6.1.2 Corrosion and its prevention, and 6.1.3 Alloys and the uses of metals. Each one has a worked solution and a mark scheme showing where the marks go.