Not Balanced! The equation doesn't satisfy the law of conservation of mass.
Hint
Element Count
Element
Reactants
Products
Status
Carbon (C)
6
6
Balanced
Hydrogen (H)
12
12
Balanced
Oxygen (O)
18
18
Balanced
Learn About Photosynthesis
What is Photosynthesis?
Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy, usually from the sun, into chemical energy stored in glucose. This process is fundamental to life on Earth as it produces oxygen and provides the energy base for most ecosystems.
The Photosynthesis Equation
6CO2 + 6H2O + light energy → C6H12O6 + 6O2
This means that six molecules of carbon dioxide and six molecules of water, using light energy, produce one molecule of glucose and six molecules of oxygen.
Key Components
Carbon Dioxide (CO2)
Absorbed from the atmosphere through tiny pores called stomata on the leaves.
Water (H2O)
Absorbed from the soil by the roots and transported to the leaves through the xylem.
Light Energy
Captured by chlorophyll, the green pigment in chloroplasts, and converted to chemical energy.
Glucose (C6H12O6)
A simple sugar that stores energy and is used by the plant for growth and development.
Oxygen (O2)
Released as a byproduct through the stomata, essential for animal respiration.
Stages of Photosynthesis
Light-dependent reactions: Occur in the thylakoid membranes, convert light energy to chemical energy (ATP and NADPH).
Calvin cycle (light-independent reactions): Occur in the stroma, use ATP and NADPH to convert CO2 into glucose.
Step-by-Step Balancing Guide
Follow these steps to balance the photosynthesis equation:
Start with the basic unbalanced equation:
CO2 + H2O + light energy → C6H12O6 + O2
Count the number of each type of atom on both sides:
Element
Reactants
Products
Carbon (C)
1 (from CO2)
6 (from C6H12O6)
Hydrogen (H)
2 (from H2O)
12 (from C6H12O6)
Oxygen (O)
3 (2 from CO2 + 1 from H2O)
8 (6 from C6H12O6 + 2 from O2)
Start with carbon. There's 1 carbon on the left and 6 on the right. Add a coefficient of 6 to CO2:
6CO2 + H2O + light energy → C6H12O6 + O2
Now carbon is balanced (6 on each side).
Next, balance hydrogen. There are 2 hydrogens on the left and 12 on the right. Add a coefficient of 6 to H2O:
6CO2 + 6H2O + light energy → C6H12O6 + O2
Now hydrogen is balanced (12 on each side).
Finally, balance oxygen. On the left: (6 × 2) + (6 × 1) = 18 oxygen atoms. On the right: 6 (from glucose) + ? (from O2).
We need 12 more oxygens on the right, so add a coefficient of 6 to O2 (6 × 2 = 12):
6CO2 + 6H2O + light energy → C6H12O6 + 6O2
Now oxygen is balanced (18 on each side).
Double-check all elements:
Element
Reactants
Products
Carbon (C)
6 (from 6CO2)
6 (from C6H12O6)
Hydrogen (H)
12 (from 6H2O)
12 (from C6H12O6)
Oxygen (O)
18 (12 from 6CO2 + 6 from 6H2O)
18 (6 from C6H12O6 + 12 from 6O2)
The equation is now perfectly balanced!
Quiz Mode
Test your knowledge of photosynthesis equation balancing!
Question 1
What is the correct coefficient for CO2 in the balanced photosynthesis equation?
Correct! 6 CO2 molecules are needed to produce one glucose molecule.
Question 2
How many oxygen molecules (O2) are produced for every glucose molecule made?
Correct! 6 O2 molecules are produced for each glucose molecule.
Question 3
Balance this equation: CO2 + H2O → C6H12O6 + O2
Perfect! The equation is balanced.
History of Photosynthesis
1770s
Joseph Priestley
Discovered that plants release oxygen, which could support combustion and animal life.
1779
Jan Ingenhousz
Showed that plants only produce oxygen in the presence of light, and that the green parts of plants are responsible.
1782
Jean Senebier
Demonstrated that plants absorb carbon dioxide and release oxygen during photosynthesis.
1804
Nicolas-Théodore de Saussure
Quantified photosynthesis by showing that water is consumed and that the increase in plant mass is more than can be accounted for by CO2 alone.
1845
Julius Robert Mayer
Proposed that plants convert light energy into chemical energy.
1930s
Cornelius van Niel
Proposed that oxygen released in photosynthesis comes from water, not carbon dioxide.
1941
Melvin Calvin
Used radioactive carbon-14 to trace the path of carbon in photosynthesis, leading to the discovery of the Calvin cycle.
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Quick Facts
Photosynthesis Efficiency
Typical plants convert about 3-6% of light energy into chemical energy.
Oxygen Production
One large tree can provide a day's supply of oxygen for 4 people.
Global Impact
Photosynthesis removes about 200 billion tons of CO2 annually.