Question

In the electrolysis of acidulated water $2.8L$ of ${O_2}$ is liberated at S.T.P If the same quantity of electricity liberates $6g$ of an another element, the equivalent weight of the element is:
A. $6g/eq$
B. $12g/eq$
C. $24g/eq$
D. $48g/eq$

Answer 1

Electrolysis is a process which uses electrical current to reduce the dissolved metal like cations which forms a metal which is coherent coating on an electrode. To calculate the equivalent weight of an element first we will find moles of ${O_2}$ and then by using a number of equivalents we will find equivalent weight.

Complete answer:
We know that at STP the molar volume is $22.4L$ . That is, for one mole the volume of solution is $22.4L$ .
So for $2.8L$ of ${O_2}$ how many moles will required, let's find out
Moles of ${O_2}$ in $2.8L$ $= \dfrac{{2.8}}{{22.4}}$
Hence, number of equivalents of ${O_2}$ will be Moles of ${O_2}$ in $2.8L$ $\times 4$
$= \dfrac{{2.8 \times 4}}{{22.4}} = 0.5$
Number of equivalent electrons $= 0.5$
Number of equivalents $= \dfrac{{weight}}{{eq.weight}}$
$0.5 = \dfrac{6}{{eq.weight}}$
Equivalent weight (E.W) $= 12g/eq$
Hence, the correct option is B.

Note:
Electrolysis is the process which is mainly used to extract metals from the ores, it is also used to refine few metals such as zinc, copper. Electrolysis is used to manufacture chlorine and also it is used for electroplating.