Question

The equivalent weight of $Fe{S_2}$ in the following reaction is $Fe{S_2} + {O_2} \to F{e^{ + 3}} + S{O_2}$
A. $\dfrac{{mol wt.}}{1}$
B. $\dfrac{{mol wt.}}{7}$
C. $\dfrac{{mol wt.}}{{11}}$
D. $\dfrac{{mol wt.}}{9}$

Answer 1

Equivalent weight of an element or radical is equal to its atomic weight or formula weight divided by the valence it assumes in the compounds.
Formula used:
Equivalent weight $= \dfrac{{mol\,weight}}{{number\,of electrons\,lost\,or\,gained}}$

Complete step by step answer:
$Fe{S_2} + {O_2} \to F{e^{ + 3}} + S{O_2}$
In the above equation the oxidation state of Fe is changed from +2 to +3.
Hence,
In this reaction, the number of electrons lost is 1.
Therefore, according to the formula,
Equivalent weight of $Fe{S_2}$ in the following reaction is $\dfrac{{mol wt.}}{1}$

Hence, option A is correct.

Additional information:
$Fe{S_2}$ Is the thermodynamically stable product of iron compounds that react with sulfide in reduced sediments, with the latter being produced mainly by microbial sulfate reduction. Consequently, pyrite is the most abundant iron-Sulphur mineral on Earth’s surface.

Note:
Equivalent weight unlike molecular weight is proportional mass of chemical entities which combine or displace other chemical entities. It is the mass of an element/compound/ion which combines or displaces 1 part of hydrogen or 8 parts of oxygen or 35.5 parts of chlorine by mass.