Question:
How will the pH of brine (aq. NaCl solution) be affected when it is electrolyzed?
Solution:
NaCl (aq)→Na+ (aq) + Cl– (aq)
Cathode: H2O(l ) + e–→ 1/2 H2(g) + OH– (aq)
Anode: Cl– (aq) → 1/2 Cl2(g) + e–
Overall reaction: NaCl(aq)+H2O(l)→NaOH(aq)+H2(g)+Cl2(g)
NaOH is a strong base, they turn the brine solution basic and pH will increase.