How to balance a chemical equation? Explain the process of photosynthesis.  Can you tell me about any experiment which uses an energy to complete its work?  

Expert Answers
gsenviro eNotes educator| Certified Educator

A balanced chemical equation is one in which the atoms of each species are equal on the reactant and product side. Let us use the example of photosynthesis to see how equations can be balanced.

Photosynthesis is the process by which plants containing chlorophyll convert sunlight into chemical energy in the form of glucose. Oxygen is also a product of this reaction. In photosynthesis, carbon dioxide and water react in the presence of sunlight to form glucose and oxygen. Thus, the basic chemical equation can be written as:

CO2 + H2O + sunlight -> C6H12O6 + O2

Let us count the number of atoms of each species on both sides of the equation:

C: reactant side = 1, product side = 6

H: reactant side = 2, product side = 12

O: reactant side = 3, product side = 8

Thus, none of the species are balanced. Let us start with carbon. We can multiply CO2 by a factor of 6 to balance it.

Step 1: 6CO2 + H2O + sunlight -> C6H12O6 + O2

Now carbon is balanced. Let us similarly balanced hydrogen by multiplying water by 6.

Step 2: 6CO2 + 6H2O + sunlight -> C6H12O6 + O2

Only oxygen remains unbalanced. There are 18 atoms of oxygen on reactant side and 8 on the product side. Let us multiply O2 by 6 to balance it.

Step 3: 6CO2 + 6H2O + sunlight -> C6H12O6 + 6O2

Now the equation is balanced in terms of all the species.

When we make tea, we boil water by supplying it with heat energy. That is an example of an experiment or process where we use energy to complete the work.

Hope this helps.