For the cell M(s)|MI₂(s)|MI₂(aq)|M(s), standard reduction potentials at 298 K are E°(M²⁺/M)=−0.12 V and E°(MI₂(s)/M)=−0.36 V. The cell temperature coefficient is 1.5×10⁻⁴ V/K. Find standard reaction enthalpy in kJ/mol (two decimal places); F=96500 C/mol.
The cell emf is −0.12−(−0.36)=0.24 V and n=2. Use ΔG°=−nFE° and ΔS°=nF(dE°/dT). Hence $\Delta H^\circ=-nF[E^\circ-T(dE^\circ/dT)]=-2(96500)[0.24-298(0.00015)]=-37692.9$ J/mol =−37.69 kJ/mol.
More Electrochemistry: Standard electrode potential and electrochemical cells. Nernst Equation and its application, relationship between electrode potential and thermodynamic quantities, Potentiometric and conductometric titrations. Ionic mobility and conductivity. Kohlrausch’s law, Debye-Hückel limiting law. Debye-Hückel- Onsager equation. questions
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