Question

a) Why is necessary to balance a chemical equation?

b) Write the balanced chemical equation for the following reactions:

1. Natural gas burns in air and combines with oxygen to form carbon dioxide and water.
2. During respiration, glucose combines with oxygen and forms carbon dioxide and water along with the release of energy.

Answer 1

a) Balanced chemical equation:

The Balanced chemical equation is

1. When the atoms of different elements of the reactants and the products are equal.
2. When the gases involved are in molecular form. Example: ${\mathrm{H}}_2,{\mathrm{N}}_2,{\mathrm{O}}_2$

The necessity to balance chemical equations:

The law of conservation of mass: In a chemical reaction, ‘the mass of the reactants must be the same as the mass of the products and this happens only if the atoms of different elements of reactants and products are equal.’

Hence, according to the Law of Conservation of mass, it is necessary to balance a chemical equation.

b)

i) Combustion reaction:

A combustion reaction is a type of chemical reaction in which a substance burns or is oxidized in the presence of Oxygen$\left({\mathrm{O}}_2\right)$ or air.

Natural gas burns in air and combines with Oxygen to form Carbon dioxide$\left({\mathrm{CO}}_2\right)$ and Water$\left({\mathrm{H}}_2\mathrm{O}\right)$ is an example of the Combustion reaction. The chemical equation for this reaction is written as,

${\mathrm{CH}}_4\left(\mathrm{g}\right)+2{\mathrm{O}}_2\left(\mathrm{g}\right)\stackrel{\mathrm{heat}}{\to }{\mathrm{CO}}_2\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+\mathrm{heat}$

ii) Respiration reaction:

Respiration is a Biochemical reaction that releases energy in cells. Respiration is also a type of Combustion reaction in which Glucose $\left({\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\right)$ produces Carbon dioxide and Water. The chemical equation of respiration is written as,

${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\left(\mathrm{s}\right)+6{\mathrm{O}}_2\left(\mathrm{g}\right)\to 6{\mathrm{CO}}_2\left(\mathrm{g}\right)+6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+\mathrm{energy}$