Final answer:
The correct reaction for the electrolysis of molten hydrogen chloride is 2HCl → H2 + Cl2, resulting in the formation of hydrogen gas and chlorine gas.
Step-by-step explanation:
The correct reaction for the electrolysis of molten hydrogen chloride is option (b) 2HCl → H2 + Cl2. During this process, hydrogen chloride dissociates into hydrogen and chlorine ions. When an electric current is passed through molten HCl, hydrogen ions (H+) are attracted to the cathode (negative electrode) and chloride ions (Cl−) move towards the anode (positive electrode).
At the cathode, hydrogen ions gain electrons (reduction) to form hydrogen gas according to the reaction:
2H+ (aq) + 2e− → H2(g).
At the anode, chloride ions lose electrons (oxidation) to form chlorine gas as per the reaction:
2Cl− (aq) → Cl2 (g) + 2e−.
Therefore, the result of electrolyzing molten HCl is the production of hydrogen gas and chlorine gas.