Answer:
6CO₂ + 6H₂O + light energy => 6O₂ + C₆H₁₂O₆
Step-by-step explanation:
Start with the skeleton equation:
CO₂ + H₂O + light energy => O₂ + C₆H₁₂O₆
If you forget, think about what a plant needs to survive: water and air, except they use our "waste" air, carbon dioxide. Trees make oxygen, as do other plants. Plants make their own food, glucose.
Count the number of atoms in the skeleton equation
CO₂ + H₂O + light => O₂ + C₆H₁₂O₆
Reactants Products
C 1 C 6
H 2 H 12
O 3 O 8
It is obvious we need to add a few coefficients to the reactant side because there are significantly fewer atoms. This becomes more of a trial and error process. Remember to keep track of the atoms each time you change coefficients.
I would start by making the carbon and hydrogen atoms even.
6CO₂ + 6H₂O + light => O₂ + C₆H₁₂O₆
Reactants Products
C 6 C 6
H 12 H 12
O 18 O 8
Now there are not enough oxygen atoms in the products. Change the coefficient in the diatomic O2 instead of glucose because the other elements are balanced.
6CO₂ + 6H₂O + light=> 6O₂ + C₆H₁₂O₆
Reactants Products
C 6 C 6
H 12 H 12
O 18 O 18
Since the number of each atom in the reactants and products are even, the balanced chemical equation for photosynthesis is:
6CO₂ + 6H₂O + light energy => 6O₂ + C₆H₁₂O₆