A potted plant with variegated leaves was taken in order to prove a factor necessary for photosynthesis. The potted plant was kept in the dark for 24 hours and then placed in bright sunlight for a few hours. Observe the diagram and answer the questions: A potted plant with variegated leaves was taken in order to prove a factor necessary for photosynthesis. The potted plant was kept in the dark for 24 hours and then placed in bright sunlight for a few hours. Observe the diagram and answer the questions:
Represent the process of photosynthesis in the form of a balanced equation.
Topic: Equation for photosynthesis
Answer
6CO₂ + 12H₂O → C₆H₁₂O₆ + 6H₂O + 6O₂
(in the presence of SUNLIGHT and CHLOROPHYLL, written above and below the arrow)
SUNLIGHT and CHLOROPHYLL are CONDITIONS, not reactants — write them on the arrow, never on the left-hand side.
WHY 12 WATER AND NOT 6: the simpler form balances arithmetically but is chemically misleading. Twelve molecules are split during PHOTOLYSIS and six are re-formed in the dark reaction, which is why water appears on BOTH sides. The ICSE marking scheme uses this form.
It also makes the point that the oxygen released comes from WATER, not from carbon dioxide — proved using radioactive oxygen-18 as a tracer.