carbon dioxide and water.

Write the reaction in terms of symbols and formulae of the substances involved and follow the four steps described in previous discussion.

Step 1:Write the unbalanced equation using correct chemical formulae for all substances. C₃H₈ + O₂ --> CO₂ + H₂ O ............(7)(Skeleton equation)

Note:Unbalanced chemical equation containing molecular formulae of the substances is known as skeleton equation.

Step 2:Compare number of atoms of each element on both sides. Find the coefficients to balance the equation. It is better to start with the most complex substance – in this case C₃ H₈.Look at the skeleton equation, and note that there are 3 carbon atoms on the left side of the equation but only 1 on the right side. If we add a coefficient of 3 to CO2 on the right side the carbon atoms get balanced.

C₃H₈ + O₂ --> 3CO₂ + H₂O ................... (8)

Now, look at the number of hydrogen atoms. There are 8 hydrogens on the left but only 2 on the right side. By adding a coefficient of 4 to the H2 O on the right, the hydrogen atoms get balanced. C₃ H₈ + O₂ --> 3CO₂ + 4H₂ O .................(9)

Finally, look at the number of oxygen atoms. There are 2 on the left side but 10 on the right side, by adding a coefficient of 5 to the O2 on the left, the oxygen atoms get balanced.

C₃ H₈ + 5O₂ --> 3CO₂ + 4H₂ O .....................(10)

Step 3: Make sure the coefficients are reduced to their smallest whole- number values. In fact, the equation (10) is already with the coefficients in smallest whole number. There is no need to reduce its coefficients, but this might not be achieved in each chemical reaction. Let us assume that you have got chemical equation as shown below:

2C₃ H₈ + 10O₂ --> 6CO₂ + ₈H₂ O ................... (11)
• Is it a balanced equation as per rules?

• How do you say?

Though the equation (11) is balanced, the coefficients are not the smallest whole numbers. It would be necessary to divide all coefficients of equation (11) by 2 to reach the final equation.