Question

The balance equation for the complete combustion of ethane is:
$A.\;2{C_2}{H_6} + 5{O_2} \to 4C{O_2} + 2{H_2}O + {\text{ Heat}}$
$B.\;2{C_2}{H_6} + 7{O_2} \to 4C{O_2} + 6{H_2}O + {\text{ Heat}}$
$C.\;{C_2}{H_6} + 7{O_2} \to 2C{O_2} + 3{H_2}O + {\text{ Heat}}$
$D.\;{C_2}{H_6} + 5{O_2} \to 2C{O_2} + 3{H_2}O + {\text{ Heat}}$

Answer 1

Hint:A balanced equation is one in which the atoms of each element present on both sides i.e. reactant and product side are equal.

Complete step-by-step answer:
For checking whether the equation of a given reaction is balanced or not we will count the number of each atom present both on the reactant side and well as product side.
$C$ is for carbon atom, $H$is for Hydrogen atom and $O$ is for Oxygen atom
$A.\;2{C_2}{H_6} + 5{O_2} \to 4C{O_2} + 2{H_2}O + {\text{ Heat}}$
In this reactant side, the total number of $C$ atoms are 4, $H$are 12 and $O$ are 10.
Product side, total number of $C$ atoms are 4, $H$ are 4 and $O$ are 10.
Here $H$ atoms are equal on both sides.

$B.\;2{C_2}{H_6} + 7{O_2} \to 4C{O_2} + 6{H_2}O + {\text{ Heat}}$
In this reactant side, the total number of $C$ atoms are 4, $H$are 12 and $O$ are 14.
Product side, total number of $C$ atoms are 4, $H$are 12 and $O$ are 14.
Here $C$, $H$, $O$ atoms are equal on both sides.

$C.\;{C_2}{H_6} + 7{O_2} \to 2C{O_2} + 3{H_2}O + {\text{ Heat}}$
In this reactant side, the total number of $C$ atoms are 2, $H$ are 6 and $O$ are 14.
Product side, total number of $C$ atoms are 2, $H$ are 6 and $O$ are 7.
Here $O$ atoms are not equal on both sides.

$D.\;{C_2}{H_6} + 5{O_2} \to 2C{O_2} + 3{H_2}O + {\text{ Heat}}$
In this reactant side, the total number of $C$ atoms are 2, $H$ are 6 and $O$ are 10.
Product side, total number of $C$ atoms are 2, $H$ are 6 and $O$ are 7.
Here $O$ atoms are not equal on both sides

Therefore, we can see that only in B option the carbon, hydrogen and Oxygen atoms are equal on both the sides. Hence option B is the correct answer.
$B.\;2{C_2}{H_6} + 7{O_2} \to 4C{O_2} + 6{H_2}O + {\text{ Heat}}$ is the balanced equation for the complete combustion of ethane.

Note: In these types of equations we must remember the properties of the elements in the periodic table and the type of reaction they undergo. Also, we must have the understanding how to balance a chemical equation.