What is the simplified chemical equation for photosynthesis?

• A. CO2 + H2O → CH2O + O2
• B. CO2 + H2O → C2H6O3 + O2
• C. CO2 + H2O → C6H12O6 + CO
• D. CO2 + H2O → C6H12O6 + O2

Answer: (D)

Photosynthesis can be viewed as CO2 and H2O using light energy to make a carbohydrate and oxygen. The simplest way to show this overall process is CO2 + H2O → CH2O + O2. CH2O is the empirical formula for carbohydrate, so this representation communicates that a carbohydrate is produced along with oxygen, and the atoms balance nicely: C1, H2, O3 on both sides. The full, explicitly balanced version would be 6 CO2 + 6 H2O → C6H12O6 + 6 O2, which is correct but less compact. The other expressions either imply the wrong product (like carbon monoxide) or use glucose without the proper proportions, which isn’t the simplest way to capture the overall reaction.