H₂O and CO₂ are the substances needed to carry out photosynthesis. Chlorophyll molecules absorb sunlight and break down molecules of H₂O, releasing O₂ and hydrogen. Then, hydrogen binds to CO₂ and forms glucose (C₆H₁₂O₆).
6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂
So this chemical reaction equation represents Photosynthesis.