Question

Aqueous copper (II) sulphate was electrolysed using the set up below.

1. When the switch was closed a gas was produced only at electrode B. Which electrode is the anode? 
2. Write the half equation for the reaction occurring at electrode B. 
3. What happens to the PH of the electrolyte during electrolysis? Explain. 
4. If carbon electrodes were replaced with copper electrodes in the cell above, write the equation of the reaction that would occur at the anode.

Answer 1

1. When the switch was closed a gas was produced only at electrode B. Which electrode is the anode? 
   • B
2. Write the half equation for the reaction occurring at electrode B. 
   • 4OH^-_(aq) → 2H₂O_(l) + O_2(g) + 4e^-
3. What happens to the PH of the electrolyte during electrolysis? Explain.
   • Becomes acidic // PH lowers, reduces H⁺ ions remain in solution as OH^- ions are discharged.
4. If carbon electrodes were replaced with copper electrodes in the cell above, write the equation of the reaction that would occur at the anode. 
   • Cu_(s)→Cu²⁺_(aq)+2e^- 

Answer 2

Electrode A
Cu+2e ->cu
It becomes acidified because the sulphite dissolves to form sulphuric (vi) acid
 Cu->cu+2e