293 K에서 0.2699 V, 303 K에서 0.2669 V

293 K에서 0.2699 V, 303 K에서 0.2669 V

 

 

아래와 같은 전지의 표준 전지 전위는

293 K에서 0.2699 V이고 303 K에서는 0.2669 V임이 관찰되었다.

Pt(s) | H2(g) | HCl(aq) | Hg2Cl2(s) | Hg(l)

 

298 K에서 다음 반응의 표준 반응 엔트로피의 값은 얼마인가?

Hg2Cl2(s) + H2(g) → 2Hg(l) + 2HCl(aq)

 

 

The standard potential of the cell

Pt(s) | H2(g) | HCl(aq) | Hg2Cl2(s) | Hg(l)

was found to be +0.2699 V at 293 K and +0.2669 V at 303 K.

Evaluate the standard Gibbs energy, enthalpy and entropy at 298 K of the reaction

Hg2Cl2(s) + H2(g) → 2Hg(l) + 2HCl(aq)

 

---------------------------------------------------

 

산화: H2 → 2H^+ + 2e^-

환원: Hg2^2+ + 2e^- → 2Hg

---> n = 2

 

 

 

ΔG = –nFE_cell

( 참고 https://ywpop.tistory.com/6519 )

 

 

 

ΔG = ΔH – TΔS

( 참고 https://ywpop.tistory.com/7438 )

 

 

 

–nFE_cell = ΔH – TΔS

 

TΔS = ΔH + nFE_cell

 

( in this case, we take the mean E

because 298 K lies midway between 293 K and 303 K. )

 

 

 

ΔH, ΔS는 온도 변화와 무관하다고 가정하면,

 

(303 K)ΔS – (293 K)ΔS

= [ΔH + 2F(0.2669 V)] – [ΔH + 2F(0.2699 V)]

= 2 × (96500 C/mol) × (–0.003 V)

= –579 C•V/mol

= –579 J/mol

( 참고: 1 J = 1 C•V https://ywpop.tistory.com/10066 )

 

 

 

(10 K)ΔS = –579 J/mol

 

ΔS = (–579 J/mol) / (10 K)

= –57.9 J/mol•K

 

 

 

답: ΔS = –57.9 J/mol•K

 

 

 

 

[키워드] assuming that the enthalpy and entropy of reaction are independent of temperature