Question

What is the balanced equation of ${{C}_{6}}{{H}_{6}}+{{O}_{2}}\to C{{O}_{2}}+{{H}_{2}}O$ ?

Answer 1

Hint : The chemical equation is defined as the symbolic representation of compounds by their symbols, or formulae performing a chemical reaction, left side including reactants, and the right side with the products formed. The balancing of a chemical equation is based on the conservation law of mass.

Complete Step By Step Answer:
First, let us know about the balanced chemical equation. It is defined as the total number of atoms present on the left side, or the reactants are equal to the atoms present on the right side, or products. We can say it is rearrangement of atoms.
As mentioned, the chemical equation needs to be balanced and is related with the concept of law of conservation of mass, it states that the mass is neither created nor destroyed. So, we can say the mass of an element used in the reaction at the beginning will be equal to the mass of the element formed at the end of reaction, or the product side.
Let the variables $p,q,r,s~$ represent integers such that: $\left[ p\cdot \left( {{C}_{6}}{{H}_{6}} \right) \right]+\left[ q\cdot \left( {{O}_{2}} \right) \right]\to \left[ r\cdot \left( C{{O}_{2}} \right) \right]+\left[ s\cdot \left( {{H}_{2}}O \right) \right]$
Considering the element $C$ , we have: $\left[ p\cdot \left( 6 \right) \right]=\left[ r\cdot \left( 1 \right) \right]\Rightarrow r=6p$
Considering the element $H$ , we have: $\left[ p\cdot \left( 6 \right) \right]=\left[ s\cdot \left( 2 \right) \right]\Rightarrow s=3p$
Considering the element $O$ , we have: $\left[ q\cdot \left( 2 \right) \right]=\left[ r\cdot \left( 2 \right) \right]+\left[ s\cdot \left( 1 \right) \right]\Rightarrow \left[ 12p+3p=15p \right]\Rightarrow q=\left( \dfrac{15}{2} \right)p$
The smallest value of $p>0~$ for which $q$ is an integer is: $p=2\Rightarrow \left[ q=15;r=12;s=6 \right]$
Therefore, the balanced equation is given as $2{{C}_{6}}{{H}_{6}}+15{{O}_{2}}\to 12C{{O}_{2}}+6{{H}_{2}}O.$
If we talk about the mass, then the mass will also remain unchanged of the atom as the number of atoms are the same as mentioned. Thus, when the chemical reaction is performed, the atoms are neither created, nor destroyed. So, in the end we can conclude that the law of conservation of mass should be followed to balance the chemical equation.

Note :
There is no need of confusion while understanding the importance of balancing the chemical equation. Just remember the number and the mass of atoms, or molecules on the left side i.e. reactant side must be equal to that of right side, i.e. product side.