Sodium sulfite (Na2SO3\text{Na}_2\text{SO}_3Na2SO3) is added to industrial boiler water to prevent internal corrosion of steel pipes. It reacts with dissolved oxygen:
2Na2SO3+O2→2Na2SO4 2\text{Na}_2\text{SO}_3 + \text{O}_2 \rightarrow 2\text{Na}_2\text{SO}_4 2Na2SO3+O2→2Na2SO4Steel pipes in untreated water corrode much faster than identical pipes in water containing dissolved sodium sulfite.
Use the equation and your scientific knowledge to explain how sodium sulfite reduces the rate of corrosion of steel.
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.