Question
(c) Hydrogen gas and oxygen gas are produced when sodium sulfate solution is electrolysed. Explain how oxygen gas is produced in the electrolysis of sodium sulfate solution. __
Answer
4.5
(321 Votes)
Joshua
Veteran · Tutor for 12 years
Answer
During the electrolysis of sodium sulfate solution, at the anode (positive electrode), hydroxyl ions (OH-) from the water are discharged over the sulfate ions. The hydroxyl ions lose electrons (oxidized) to the anode and are transformed into water and oxygen gas, as illustrated by the reaction -- 4OH−(aq) —> O2(g) + 2H2O(l) + 4e−. Therefore, oxygen gas is generated during the electrolysis due to this process of 'oxidation'. This yield is characterized by gas bubbles, specifically around the anode.
Explanation
Sodium sulfate is an ionic compound dissolved in water, so the solution can conduct electricity, which is the basic requirement for electrolysis. Now let's expound the process of how oxygen gas is produced.In the case of the electrolysis of aqueous solutions, water is ionized to some extent into its constituent parts, hydrogen and hydroxyl ions (H+ and OH-), under the effect of the applied electric field. During the electrolysis of sodium sulfate, at anode, either the sulfate ions or the hydroxyl ions will discharge. In this case, the hydroxyl ions are the ones preferentially discharged due to their position in the electrochemical series, which outlines the ease of discharge of ions based on their reduction potentials. The half-equation for this reaction is 4OH−(aq) —> O2(g) + 2H2O(l) + 4e−, which showcases the production of oxygen gas alongside water. Here, the gaseous oxygen that is produced gives rise to bubbles during the electrolysis. Therefore, when looking especially in the vicinity of the anode (positive electrode), the bubbles being produced are of oxygen gas.