Question

What would be the electrode potential for the given half cell reaction at pH = 5?______ 

2H₂O→O₂ + 4HÅ + 4e^– ; E⁰ _red = 1.23 V 

(R = 8.314 J mol^–1 K^–1 ; Temp = 298 K; oxygen under std. atm. pressure of 1 bar)

Answer 1

2H₂O(l) → O₂(g) + 4H⁺ + 4e^– ; E⁰_red. = 1.23V

From nernst equation

Comments

Why Ered is taken negative ??

---

Ered shows oxidation reaction and in a galvanic (voltaic) cell, the anode is considered negative and the cathode is considered positive. This seems reasonable as the anode is the source of electrons and cathode is where the electrons flow.

Answer 2

E = –1.23 + 0.295 

E = –0.935