Question

Calculate the standard cell potential at 25 ∘C for the reactionX(s)+2Y+(aq)→X2+(aq)+2Y(s)where ΔH∘ = -829 kJ and ΔS∘ = -367 J/K

Answer 1

Answer:

The standard cell potential at 25 ∘C for the reaction is 2.72 Volts.

Explanation:

Δ°G = Δ°H - TΔ°S (Gibb's equation)

Δ°G =  Gibbs free energy

Δ°H = Enthalpy of the reaction at temperature T

Δ°S = Entropy of the reaction at temperature T

$\Delta G^o=-nfE^o_{cell}$

n = number of electrons transferred

F = Faraday's constant = 96500 C

$E^o_{cell}$ = standard electrode potential of the cell

We have:

Δ°H = -829 kJ = -829000 J

Δ°S = -367 J/K

T = 25 C = 298.15 K

$\Delta G^{o}=-829000 J - (298.15 K\times -367 J/K) = -719,578.95 J$

$X(s)\rightarrow X^{2+}(aq)+2e^-$

$2Y^++2e^-(aq)\rightarrow 2Y(s)$

n = 2

$-719,578.95 J=-2\times 96500 C\times E^o_{cell}$

$E^o_{cell}=\frac{-719,578.95 J}{-2\times 96500 C}=3.73 V$

The standard cell potential at 25 ∘C for the reaction is 2.72 Volts.