Question

Balanced equation for the reaction between zinc and dilute sulphuric acid is:
A) $Zn + {H_2}S{O_4}(dil) \to ZnS{O_4} + 2{H_2}$
B) $Zn + 2{H_2}S{O_4}(dil) \to ZnS{O_4} + 2{H_2}$
C) $2Zn + {H_2}S{O_4}(dil) \to 2ZnS{O_4} + {H_2}$
D) $Zn + {H_2}S{O_4}(dil) \to ZnS{O_4} + {H_2}$

Answer 1

Hint: First you need to write chemical equation (symbolic representation of the chemical reaction) of zinc $(Zn)$ reacting with dilute sulphuric acid (${H_2}S{O_4}$). A balanced chemical reaction is the one in which the number of atoms of all the elements are equal on both sides (that is, the reactant and the product side) of the reaction. To balance the equation, count the number of atoms of each element on both sides and make them equal.

Complete step by step solution:
A chemical equation is the symbolic representation of the chemical reaction where reactants and products are represented by their respective chemical formulae. If in a chemical equation, the total number of atoms of each molecule in the reactant side (left-hand side) is equal to the total number of atoms of each molecule in the product side (right-hand side), then the chemical reaction is said to be a balanced chemical equation.
The reaction of zinc with dilute sulphuric acid is a non-metal displacement redox reaction. This type of redox reaction involves hydrogen displacement from acids by a metal. Thus, the chemical equation for the reaction between zinc $(Zn)$ and dilute sulphuric acid (${H_2}S{O_4}$) can be written as:
$Zn + {H_2}S{O_4}(dil) \to ZnS{O_4} + {H_2}$
The elements involved in the reaction are Zn, H, S, and O. Now in the above reaction, comparing the total number of atoms of each element on the reactant side and the product side:

Element	Reactant side (LHS)	Product side (RHS)
Zinc (Zn)	1	1
Hydrogen (H)	2	2
Sulphur (S)	1	1
Oxygen (O)	4	4

It is clear from the above table that total number of atoms of each element involving in the reaction, are equal on both sides, hence equation: $Zn + {H_2}S{O_4}(dil) \to ZnS{O_4} + {H_2}$, is a balanced equation.
Thus, option D is correct.
Note: It should be noted that reaction of zinc with sulphuric acid is an example of non-displacement redox reactions. In these reactions, metal atoms displace hydrogen from acids. These reactions are used to prepare hydrogen gas (${H_2}$) in the laboratory.