Question

In the reaction given below:
$x\text{HI}+y\text{HN}{{\text{O}}_{3}}\to \text{NO+}{{\text{I}}_{2}}\text{+}{{\text{H}}_{2}}\text{O}$. The value of x and y will be:
A. $x=3$, $y=2$
B. $x=2$, $y=3$
C. $x=6$, $y=2$
D. $x=6$, $y=1$

Answer 1

Hint: To solve this question, you have to use the law of conservation of mass. Use hit and trial method to balance the number of atoms on both sides and then you can figure out the required values of x and y.

Complete step by step solution:
Let us solve this question by understanding a chemical equation and the law of conservation of mass.
So, a chemical equation shows us the substances involved in a chemical reaction where the substances that react are known as reactants while those are produced are called products.
The law of conservation of mass states that mass in an isolated system is neither created nor destroyed by a chemical reaction or physical transformation. According to the law, the mass of the products in a chemical reaction must be equal to that of the mass of the reactants.
So, here in the question the reaction given is as follows:
$x\text{HI}+y\text{HN}{{\text{O}}_{3}}\to \text{NO}+{{\text{I}}_{2}}\text{+}{{\text{H}}_{2}}\text{O}$ and we have to find out the values of x and y.
The redox reaction involves:
$(2{{I}^{-}}\to {{I}_{2}}+2{{e}^{-}})\times 3$ --(i)
$(NO_{3}^{-}+3{{e}^{-}}\to NO)\times 2$ --(ii) [Here the number multiplied implies the number of electrons gained or lost and is done in a criss-crossed manner].
So, after adding (i) and (ii) we get:
$6{{I}^{-}}+2NO_{3}^{-}\to 2NO+3{{I}_{2}}$
So, the reaction will look like:
$6HI+2HN{{O}_{3}}\to 2NO+3{{I}_{2}}+4{{H}_{2}}O$
Therefore, $x=6\text{ and }y=2$.

Hence, the correct option is C.

Note: Some of the examples of law of combustion of mass include combustion process such as burning of wood where it follows conservation of mass as it involves oxygen, carbon dioxide, water vapor and ashes.