Question

Oxygen and hydrogen gas are produced at the anode and cathode respectively, during the electrolysis of fairly concentrated aqueous solution of:
A.$K_{2}SO_{4}$
B. $AgNO_{3}$
C. $H_{2}SO_{4}$
D. $NaOH$

Answer 1

Hint: Michael Faraday gives the term electrolysis in the 19th century. In order to predict the products of electrolysis we need to learn about the concept of electrolysis and how it works.

Complete step by step answer:
Electrolysis process can be defined as a process of decomposing ionic compounds into their elements by passing direct electric current to the compound in fluid form. The anions are oxidized at anode and cations are reduced at cathode.
Factors affecting the electrolysis process will be as follows:
The nature of electrolytes
State and nature of electrolytes
Overvoltage at the electrodes
Nature and electrode potential of ions present in electrolytes
A better method for the prediction of products of electrolysis of an aqueous solution of the electrolytes will be on the basis of their electrode potential values.
From the reactivity series of metals, the reduction potential value of potassium ion $(K^{+})$ and sodium ion $Na^{+}$ are lower than the hydrogen ion $H^{+}$, then hydrogen ion will get preferably reduced to produce hydrogen gas at cathode. Also, the oxidation potential value of hydroxide ion $OH^{-}$ is higher than sulphate ion$S{O_{4}}^{2-}$, so it will be oxidized first to produce oxygen gas at anode.
Therefore, oxygen and hydrogen gas are produced at the anode and cathode respectively, during the electrolysis of fairly concentrated aqueous solution of $K_{2}SO_{4}$ , $H_{2}SO_{4}$ and $NaOH$ .
So, the correct answer is “Option A, C & D”.

Note:
You may have noticed that this is the opposite of a galvanic cell, where the anode is negative and the cathode is positive. Electrolysis process can be used for the determination of equivalent weights of the substances, purification of metals, in manufacturing pure gases, electroplating for corrosion resistance, ornaments etc.