CBSE
Class 10 Class 12
A chemical equation can be divided into two types - Balanced chemical equation and unbalanced chemical equation.
According to Law of conservation of Mass. Matter can neither be created nor destroyed in a chemical reaction.
Therefore, a number of elements involved in the chemical reaction should remain same at reactant and product side.
STEPWISE BALANCING (Hit and Trial)
Step 1. Write a chemical equation and draw boxes around each formula.
Fe + H2O → Fe3O4 + H2
Step 2. Count the number of atoms of each element on both the sides of the chemical equation.
| Element | No. of atoms at reactant side | No. of atoms at product side |
| Fe | 1 | 3 |
| H | 2 | 2 |
| O | 1 | 4 |
Step 3. Equalise the number of atoms of an element which has a maximum number by putting in front of it.
Fe + 4H2O → Fe3O4 + H2
Step 4. Try to equalize all the atoms of elements on reactant and product side by adding coefficient in front of it.
3Fe + 4H2O → Fe3O4 + 4H2
Now all the atoms of elements are equal on both sides.
Write the physical states of reactants and products.
3Fe (s) + 4H2O (g) → Fe3O4 ( s) + 4H2 (g)
Solid state = (s)
Liquid state = (l)
Gaseous state = (g)
Aqueous state = (aq)
Step 6. Write necessary conditions of temperature, pressure or catalyst on arrow above or below.
A chemical equation can be divided into two types - Balanced chemical equation and unbalanced chemical equation.
According to Law of conservation of Mass. Matter can neither be created nor destroyed in a chemical reaction.
Therefore, a number of elements involved in the chemical reaction should remain same at reactant and product side.
STEPWISE BALANCING (Hit and Trial)
Step 1. Write a chemical equation and draw boxes around each formula.
Fe + H2O → Fe3O4 + H2
Step 2. Count the number of atoms of each element on both the sides of the chemical equation.
| Element | No. of atoms at reactant side | No. of atoms at product side |
| Fe | 1 | 3 |
| H | 2 | 2 |
| O | 1 | 4 |
Step 3. Equalise the number of atoms of an element which has a maximum number by putting in front of it.
Fe + 4H2O → Fe3O4 + H2
Step 4. Try to equalize all the atoms of elements on reactant and product side by adding coefficient in front of it.
3Fe + 4H2O → Fe3O4 + 4H2
Now all the atoms of elements are equal on both sides.
Write the physical states of reactants and products.
3Fe (s) + 4H2O (g) → Fe3O4 ( s) + 4H2 (g)
Solid state = (s)
Liquid state = (l)
Gaseous state = (g)
Aqueous state = (aq)
Step 6. Write necessary conditions of temperature, pressure or catalyst on arrow above or below.
A chemical reaction can be represented by the chemical equation. It involves uses of the symbol of elements or chemical formula of reactant and product with mention of physical state.
The necessary conditions such as temperature, pressure or any catalyst should be written on arrow between reactant and products. For example, Magnesium is burnt in air to form magnesium oxide.
Mg (Reactant) + O2 (Reactant) → MgO (product)
An equation shows a change of reactants to products through an arrow placed between them. The reactants are written on the left-hand side (LHS) with a plus sign (+) between them. Similarly, products are written on the right-hand side (RHS) with a plus sign (+) between them. The arrowhead points towards the products and shows the direction of the reaction.
Example: A + B → C +D
In this equation, A and B are called reactants and C and D are called products. The arrow shows the direction of the chemical reaction.
