Question

can u answer the following questions?

4. Silver oxide is used in "button batteries to power electric watches and other trinkets. These batteries generate a potential of 1.55 V and consist of a Zn anode and a Ag20 cathode immersed in a concentrated solution of KOH. The cathode reaction is based on the reduction of Ag20 to Ag metal. At the anode, Zn is oxidized to solid Zn(OH)2. Write the net ionic balanced electrochemical cell reaction and calculate the value of ΔGcell ( F-965x104 C/mol) E for Ag20 to Ag (s) is 0.342 V E for Zn(OH)2 (s) to Zn (s) is -1.249 V 5. A Copper-Zn electrochemical cell (galvanic) proceeds until the [Cu210.10 M and [Zn2] -19.0 M, what would be the value of Eell at 25 C?

Answer 1

4) Reduction at cathode : Ag⁺ (aq)+ e- -----------------> Ag(s) Eo = 0.342 V

Oxidation at anode : Zn(s) -----------> Zn²⁺ (aq) + 2e- Eo = + 1.249 V

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Zn(s) + 2Ag⁺ (aq)  -----------------> Zn²⁺ (aq)+ 2Ag(s)

E_cell = E^o_reduction of reaction at cathode+E^o_oxidation of reaction at anode

= 0.342 V + 1.249 V

= + 1.591 V

E_cell = + 1.591 V

no of electrons transferred n = 2

We know that ΔGcell = -nFEcell , F = 9.65 x 10⁴ C/mol

  ΔGcell = -2 x 9.65 x 10⁴ C/mol x 1.591 V

   = - 307063 J

= - 307 kJ

ΔGcell = - 307 kJ

Therefore,

ΔGcell = - 307 kJ

5)   

Reduction at cathode : Cu²⁺ (aq)+ 2e- -----------------> Cu(s) Eo = 0.34 V

Oxidation at anode : Zn(s) -----------> Zn²⁺ (aq) + 2e- Eo = 0.76 V

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Zn(s) + Cu²⁺ (aq)  -----------------> Zn²⁺ (aq) + Cu(s)

E^o_cell = E^o_reduction of reaction at cathode+E^o_oxidation of reaction at anode

= 0.34 V + 0.76 V

= + 1.1 V

E_cell = + 1.1 V

no of electrons transferred n = 2

Zn(s) + Cu²⁺ (aq)  -----------------> Zn²⁺ (aq) + Cu

Given that [Cu²⁺]= 0.1 M , [Zn²⁺]= 19.0 M

E_cell = E^o_cell - (0.059/n) {Iog [Zn²⁺ (aq)]/[Cu²⁺ (aq)]}

= 1.1 - (0.059/2) log {[19.0]/ [0.1]}

= + 1.03 V

E_cell = + 1.03 V

Therefore,

E_cell at 25oC is  + 1.03 V