Reversible Reactions

IGCSE Edexcel Chemistry
3.17-3.18 Reversible reactions
Key Concept: Reversible reactions can go forwards and backwards and are shown with a double arrow.

Section A: Definitions and Symbols

1. What does the symbol <==> represent in a chemical equation? [1]
2. Give one example of a reversible reaction from the specification. [2]

Section B: Specific Examples

3. Write the reversible equation for hydrated copper sulfate heating to form anhydrous copper sulfate. [2]
4. Describe what you observe when ammonium chloride is heated and cooled. [2]

Total marks: 7

Mark Scheme

1. Reaction goes forwards and backwards (reversible) [1]
2. Hydrated copper sulfate <=> anhydrous copper sulfate + water; or ammonium chloride <=> ammonia + hydrogen chloride [2]
3. CuSO4.5H2O <=> CuSO4 + 5H2O [2]
4. White solid forms on cooling; colorless gas on heating; solid sublimes and re-forms [2]