Chemical Equation - Class Notes

Question 1 What is a chemical equation?

Question 2 Give an example of chemical equation?

Question 3 What is a balanced equation?

Question 4 What is an unbalanced equation?

Question 5 What are the steps of balancing the equation?

Chemical Equation

The method of representing a chemical reaction with the help of symbols and formula is called chemical equation.

For Example :

Zinc + Sulphuric acid → Zinc Sulphate + Hydrogen

Reactants Products

The reactants are always written on left hand side in an equation with a plus sign between the.

The products are always written on right hand side in an equation with a plus sign between them.

A chemical equation is the short hand method of representing chemical reaction.

Balanced Equation: It has equal number of atoms of different elements in reactants and products.

Unbalanced Equation: It has unequal number of atoms of different elements in reactants and products.

H₂ + O₂ → H₂O

Balancing of Chemical Equation

The process of making the number of different types of atoms equal on both side of an equation is called balancing equation.

(1) Write down the chemical reaction in the form of word equation, keeping reactants on left hand side and products on right hand side.

(2) Write symbol and formula of all reactants and products in word equation.

(3) Balance the equation by multiplying the symbols and formula by smallest possible figures.

(4) Make the equation informative by indicating physical state, heat changes, reaction condition.

(5) Indicate the physical state of reactant and products in an equation. We use the symbols as: solid(s), liquid(l), gas(g).

Example of balancing the equation

(1) CH_{4 +}O₂→ CO_2 +H₂O

Step 1) Make H atoms equal(Multiply products by 2)
CH_{4 +}O₂→ CO_2 +2H₂O

Step 2) Multiply oxygen of reactants by 2

CH_{4 +}₂O_{2 →}CO_2 +₂H₂O _{Balanced equation}

(2) (Cu)₂SO₄ + NaOH → Cu(OH)₂₊Na₂SO₄

Step 1) Multiply sodium hydroxide by 2

CuSO₄ + 2 NaOH → Cu(OH)₂+ Na₂SO_{4 Balanced equation}

(3) Fe +H₂O → Fe₃O_4 +H₂

Step 1) Multiply Fe by 3 on left hand side

3 Fe₊H₂O → Fe₃O_4 +H₂

Step 2)Multiply oxygen by 4 on left hand side

3 Fe_{+ 4}H₂O → Fe₃O_4 +H₂

Step 3)Multiply hydrogen by 4 on right hand side

3 Fe_{+ 4}H₂O → Fe₃O_4 +₄H₂_{Balanced equation}

Other Notes from Chapter 1 Chemical Reaction and Equation