Question

When an aqueous solution of zinc sulfate is subjected to electrolysis, 280 ml of oxygen gas at STP is liberated at the anode. Calculate the quantity of electricity passed through the electrolyte.
A. 0.05 F
 B.0.5 F
 C.0.005 F
 D.5F

Answer 1

Hint: Faraday’s law of electrolysis was given by Michael Faraday which is used to determine magnitudes of electrolytic effects and chemical changes. This law is very important to detect the number of substance deposits at electrodes.

Complete step by step answer:
Faraday’s second law of electrolysis states that the masses of different ions liberated at the electrodes, when the same amount of electricity is passed through different electrolytes are directly proportional to their chemical equivalents. We can also say that the electrochemical equivalent(Z) of an element is directly proportional to their equivalent weight(E).
Let us suppose \[{w_1}\]and \[{w_2}\] are the deposited amount of any substance and \[{E_1}\] \[{E_2}\] are their respective equivalent weights. As per this law, we can get it for silver as shown below-
 \[\dfrac{{{w_1}}}{{{w_2}}} = \dfrac{{({E_1})}}{{({E_{2l}})}} = \dfrac{{{{\left( {\dfrac{{atomic\,weight}}{{valency\,factor}}} \right)}_1}}}{{{{\left( {\dfrac{{atomic\,weight}}{{valency\,factor}}} \right)}_2}}}\]
Faraday’s second law is also used to determine the chemical equivalents of different electrolytes. The value of Faraday’s constant is equal to 96485 \[Cmo{l^{ - 1}}\] . The current of 96500 coulombs is known as Faraday charge.

Now in this question, 280 ml of oxygen gas at STP is liberated at the anode. The reaction of the anode is as follows,
 \[2{H_2}O(l) \to {O_2}(g) + 4{H^ + }(aq) + 4{e^ - }\]
In this reaction, 4 electrons are used. therefore, it requires 4faraday electricity.
That is 1 mole of oxygen formed by 4faraday electricity, now one mole =22.4 L oxygen.
So 280ml oxygen is equal to 0.280L oxygen.
 22.4 ml required 4 faraday
So, 1 ml required \[\dfrac{4}{{22.4}}\] faraday
So, 0.280 ml required \[
  \dfrac{4}{{22.4}} \times 0.280 \\
   = 0.05F \\
 \]
 the quantity of electricity passed through the electrolyte to liberate 280 ml of oxygen gas at STP is at the anode is 0.05 F.
so, the correct option is, A.

Note:One Faraday is defined as the quantity of electricity flowing through an electrolyte which will release the one-gram equivalent of any substance at any electrode. Faraday’s constant(F) is charged in a unit of coulombs(C) for one mole of the electron.