Look at the chemical equation for a key step in the Contact process:
2SO2(g)+O2(g)⇌2SO3(g) 2\text{SO}_2(\text{g}) + \text{O}_2(\text{g}) \rightleftharpoons 2\text{SO}_3(\text{g}) 2SO2(g)+O2(g)⇌2SO3(g)What is meant by the symbol ⇌ \rightleftharpoons\,⇌ in the equation?
A reaction that goes to completion.
A reaction that is reversible.
A reaction that requires a catalyst.
A reaction that is endothermic.
25 exam-style questions on OCR GCSE Chemistry Equilibria. Each one has a worked solution and a mark scheme showing where the marks go.