Photosynthesis
Section: 10. Chemistry of the Environment | Syllabus: Cambridge IGCSE Chemistry (0620)
Photosynthesis
Photosynthesis is the reaction between carbon dioxide and water to produce glucose and oxygen, in the presence of chlorophyll and using energy from light.
Word Equation
carbon dioxide + water → glucose + oxygen
Symbol Equation (Supplement)
6CO₂(g) + 6H₂O(l) → C₆H₁₂O₆(aq) + 6O₂(g)
By removing CO₂ from the air, photosynthesis is the natural process that offsets some of the carbon dioxide released by combustion - linking back to the strategy of planting trees to reduce climate change.
Worked Example
- Question: state the word equation for photosynthesis, and the symbol equation.
- Answer: word equation - carbon dioxide + water → glucose + oxygen; symbol equation - 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Common Mistakes
- ❌ Writing the symbol equation with mismatched numbers, e.g. CO₂ + H₂O → C₆H₁₂O₆ + O₂ (unbalanced)
- ✓ six CO₂ and six H₂O are needed to build one C₆H₁₂O₆, releasing six O₂ - all four numbers (6, 6, 1, 6) must be included for the equation to balance
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