How to Balance a Chemical Equation Step by Step (Hit and Trail Method)

Balancing chemical equations is one to the most important topic in class 9 and 10 Science. In RBSE exams, students often lose marks in this topic. The method is explained in Chapter 1 Chemical Reactions and Equations of NCERT Class 10 Science is Hit and Trial Method. This is a simple way to balance equations.

This post explains all steps for balancing a chemical equation. This guide gives you a complete, exam ready method, multiple solved examples, mistakes to avoid and practice examples.

Why must a Chemical Equation be Balanced?

A chemical reaction follows the ‘Law of Conservation of Mass’. According to this law “Atoms are neither created nor destroyed during a chemical reaction.”

Therefore, atoms of each element (in reactants and products) must be equal on the left-hand side and right-hand side of the equation.

Important Terms Related to Chemical Equation

First, you must know a few terms before learning balancing chemical equation.

·     Skeletal Equation: An unbalanced equation showing only formula of reactants and products is called skeletal equation.

·     Balanced Equation: An equation with equal numbers of atoms on both sides is called balanced equation.

·     Coefficient: Number written before a formula.

·     Subscript: Small number in a formula

Hit and Trial Methos (Step by step)

This method is an easy way to balance a chemical equation specially for class 9 and 10.

We will balance:

Fe + H₂O → Fe₃O₄ + H₂

Step 1- Draw boxes around the reactants and products

First of all, we draw boxes around the chemical formula given in the equation so that we do not touch the subscripts in the formula.

 

Step 2 – Count atoms

We count the numbers of atoms of each element on both sides.

Elements	LHS	RHS
Fe	1	3
H	2	2
O	1	4

 

Step 3 – Follow the MNOH Rule to balance

We will follow MNOH rule where:

M= metal

N = non-metal

O= oxygen

H = hydrogen

First of all, we balance metal on both sides, then non-metal, oxygen and hydrogen.

In the given Fe is a metal so we balance it first.

We put 3 before Fe on left hand side

 

3Fe + H₂O → Fe₃O₄ + H₂

There is no non metal in the equation, so we will balance oxygen on both sides

We put 2 before 4 before H₂O

3Fe + 4H₂O → Fe₃O₄ + H₂

Now in the last we will balance hydrogen

We put 4 before H₂ on RHS

3Fe + 4H₂O → Fe₃O₄ + 4H₂

Now we recount all the elements on both sides

Elements	LHS	RHS
Fe	3	3
H	8	8
O	4	4

 

We can see all the elements have same numbers of atoms on both sides so the equation is balanced now.

 Balanced Chemical Equation

3Fe + 4H₂O → Fe₃O₄ + 4H₂

 

Golden rule to balance equation

i.     Change coefficient but never change subscript

ii.   Balance metal first, then non-metal, oxygen and hydrogen

iii. Use smallest whole numbers

iv.  Recount atoms on both sides

v.    Add state symbols if required

Solved Examples of Balanced Chemical Equations

After learning steps for balancing chemical equations, you can easily understand the following examples of chemical equations.

(i)Mg + O₂→ MgO

  2Mg + O₂→ 2MgO

(ii) Al + O₂  → Al₂O₃

    4Al + 3O₂  → 2Al₂O₃

 

(iii)Na + H₂O → NaOH + H₂

    2Na + 2H₂O → 2NaOH + H₂

 

(iv)KClO₃ → KCl + O₂

     2KClO₃ → 2KCl + 3O₂

(v)Zn + HCl →ZnCl₂ +H₂

   Zn + 2HCl →ZnCl₂ +H₂

(vi)Pb(NO₃)₂   →    PbO + NO₂  +O₂

    2Pb(NO₃)₂    →   2PbO + 4NO₂  +O₂

(vii)BaCl₂  + Na₂SO₄ →BaSO₄ +NaCl

     BaCl₂  + Na₂SO₄ →BaSO₄ +2NaCl

 

Special Tips for Balancing Different Types of Reactions

You can also follow the tips for special types of chemical reactions.

Type of Reaction	Tips
Combination reaction	Balance Oxygen carefully
Decomposition reaction	Balance oxygen at the end
Displacement reaction	Balance the displaced element first
Double displacement reaction	Treat polyatomic ions (SO4 , NO3) as a unit if unchanged
Redox reaction	Balance oxygen and hydrogen at last

 

Common Mistakes in Balancing Equation

Students sometimes make mistakes in balancing chemical equations. Avoid these mistakes:

    ·     If you change subscript of any element, the formula of substance changes

    ·     Do not forget to balance diatomic gases like H₂, O₂, Cl₂

    ·     Do not use fractions, always use whole numbers

·     Always recount atoms

 

Practice Sets for Balancing Chemical Equations

You can try to balance the following chemical equations by the above method.

 (i) H₂ + Cl₂ →HCl

(ii) Fe + O₂ →Fe₂O₃

(iii) Ca + H₂O →Ca(OH)₂ + H₂

(iv) N₂ +H₂ → NH₃

(v) Al +HCl →AlCl₃ H₂

(vi) Na₂CO₃ +HCl →NaCl + H₂O  + CO₂

(vii) Cu + O₂ →CuO

(viii) Fe₂O₃ +Al →Al₂O₃ +Fe

(ix) C₂H₆ + O₂ →CO₂+ H₂O

(x) NH₃ +O₂ →NO + H₂O

(xi) AgNO₃ + NaCl →AgCl + NaNO₃

Conclusion

 If you follow this Hit and Trail method carefully and practice daily, you can balance every chemical equation.