Question: In the reaction:\[Pb + Pb{O_2} + {H_2}S{O_4} \to PbS{O_4} + {H_2}{O_2}\] The equivalent weight of ...

Question

In the reaction: $Pb + Pb{O_2} + {H_2}S{O_4} \to PbS{O_4} + {H_2}{O_2}$
The equivalent weight of ${H_2}S{O_4}$ is
(a) M
(b) M/2
(c) 2 M
(d) M/4

Answer 1

Solution

In this whole equation, we need to find the equivalent weight of sulphuric acid which is a strong acid and gives two hydrogen ions and one sulphate ion on dissociation. The equivalent weight is calculated by dividing the molecular weight by the basicity factor.

Complete step by step answer:
The equivalent weight is defined as the mass of a substance present in grams which joins or replaces the eight gram of hydrogen or 1.007 grams of oxygen.
The formula to calculate the equivalent weight is shown below.
$E.W = \dfrac{M}{B}$
Where,
E.W is the equivalent weight.
M is the molecular weight
B is the basicity of acid.
The basicity is defined as the number of replaceable hydrogen ions present which can be replaced by other atoms.
The given reaction is shown below.
$Pb + Pb{O_2} + {H_2}S{O_4} \to PbS{O_4} + {H_2}O$
In this reaction, lead reacts with lead oxide and sulphuric acid to form lead sulphate and water.
The balanced equation is shown below.
$Pb + Pb{O_2} + 2{H_2}S{O_4} \to 2PbS{O_4} + 2{H_2}O$
In this reaction, one mole of lead reacts with one mole of lead oxide and two mole of sulphuric acid to give two mole of lead sulphate and two mole of water.
The sulphuric acid is a strong acid which dissociates into its constituent ions.
${H_2}S{O_4} \to 2{H^ + } + SO_4^ -$
In this reaction, one mole of sulphuric acid dissociates into two mole of hydrogen ion and one mole of sulphate ion.
The basicity of sulphuric acid is 2.
To calculate the equivalent weight of the sulphuric acid, substitute the value in the formula.
$\Rightarrow E.W = \dfrac{M}{2}$
Thus, the equivalent weight of ${H_2}S{O_4}$ is M/2.
Therefore, the correct option is B.

Note:
The formula of the equivalent weight depends on the type of compound, if the equivalent weight of base is needed to be calculated then the molecular weight is divided by the acidity factor which is the number of replaceable hydroxide ions. For redox reaction, the molecular weight is divided by the n-factor which is the total number of charges exchanged during the reaction.