Question

Calculate the standard change in Gibbs free energy, Δ?∘rxnΔGrxn∘ , for the given reaction at 25.0 ∘C25.0 ∘C . Consult the table of thermodynamic properties for standard Gibbs free energy of formation values.

KCl(s)↽−−⇀K+(aq)+Cl−(aq)KCl(s)↽−−⇀K+(aq)+Cl−(aq)

Δ?∘rxn=

Determine the concentration of K+(aq)K+(aq) if the change in Gibbs free energy, Δ?rxnΔGrxn , for the reaction is −8.31 kJ/mol−8.31 kJ/mol .

[K+]=

Answer 1

∆G° = ∆G°_K⁺ + ∆G°_Cl^- - ∆G°KCl = -283.27 -131.23 -(-409.14)

= - 5.36 kJ/mol (Answer)

KCl(s) $\rightarrow$ K⁺(aq) + Cl^-(aq)

[K⁺] = [Cl^-]

∆G = ∆G° + RT ln([K⁺][Cl^-])

-8.31×1000 = -5.36×1000 + 8.314 × 298 × ln[K⁺]²

ln [K⁺] = - 0.595

[K⁺] = e^-0.595 = 0.55 M. (Answer)