Question

What is the equivalent mass of $KMn{O_4}$ in $2KMn{O_4} + 16HCl \to 2KCl + 2MnC{l_2} + 8{H_2}O + 5C{l_2}$ ?

Answer 1

Hint: Atoms of different elements chemically bond with each other to form chemical compounds. The elements within the compound are present in determined finite proportions. This is to ensure that the combining capacities or valency for each of these atoms within the compound are equal.

Complete answer:
Atoms and molecules react in chemically equal proportions with each other. The equivalent mass defines the weight of each of the substances within the reaction required to ensure a chemically stable final compound.
The definition of equivalent mass is as follows:
“All elements combine with each other according to the laws of chemical combination, and the number of parts by which an element combines with 1 part by mass of hydrogen, or 8 parts by mass of oxygen, or 35.5 parts by mass of chlorine, or one gram of any other element, is the value of the equivalent mass of the element.”
It can be calculated using the equation given below.
Equivalent Weight $ = \dfrac{M}{{OS}}$
where $M$ is the molecular weight and $OS$ is the difference in the oxidation state.
According to the equation, the reaction is given by the following equation:
$2KMn{O_4} + 16HCl \to 2KCl + 2MnC{l_2} + 8{H_2}O + 5C{l_2}$
This equation is balanced with respect to mass and charge. The oxidant in the above equation is permanganate, which is reduced to $M{n^{2 + }}$. The equation of this reduction process is given by.
$Mn{O_4}^ - + 8{H^ + } + 5{e^ - } \to M{n^{2 + }} + 4{H_2}O$
The molar mass of potassium permanganate is $158.03 \cdot g \cdot mo{l^{ - 1}}$ which reacts with 5 moles of electrons. Thus, its equivalent mass of $KMn{O_4}$ is $31.6 \cdot g \cdot mo{l^{ - 1}}$.

Note:
In different mediums, the oxidation states represented by $KMn{O_4}$ vary. Its oxidation state reducing to $ + 2$ in acidic medium varies from its oxidation state reducing to $ + 4$ in a neutral medium.