NEET2013ChemistryElectrochemistryActual
A button cell used in watches functions as following Zn (s)+ Ag ₂ O (s) & + H ₂ O (l) 2 Ag (s) + Zn ²⁺( q)+2 OH ⁻( q) If half cell potentials are aligned Zn ²⁺(a q)+2 e⁻ & Zn (s) ; E^ =-0.76 ~V Ag ₂ O (s)+ H ₂ O (l) & +2 e⁻ & 2 Ag (s)+2 OH ⁻(a q), & E^ =0.34 ~V aligned The cell potential will be
Options
- A1.10 ~V
- B0.42 ~V
- C0.84 ~V
- D1.34 ~V
Correct answer
A. 1.10 ~V
Step-by-step solution
Anode is always the site of oxidation thus anode half cell is Zn ²⁺( aq )+2 e ⁻ Zn ( s ) ; E^ =-0.76 ~V Cathode half cell is aligned & Ag ₂ O (s)+ H ₂ O (l)+2 e⁻ 2 Ag (s)+2 OH & E⁻(a q) ; E^ =0.34 ~V &= E_ cathode ^ -E_ anode ^ &= 0.34-(-0.76)=+1.10 ~V aligned