Core Electrochemistry Formulas

1. Cell EMF: $E^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode}$

2. Nernst Equation (general): $E = E^\circ - \frac{RT}{nF}\ln Q$

3. Nernst Equation at 25°C (298 K): $E = E^\circ - \frac{0.0592}{n}\log Q$

4. EMF at equilibrium (E = 0): $E^\circ = \frac{0.0592}{n}\log K \quad \Leftrightarrow \quad \log K = \frac{nE^\circ}{0.0592}$

5. Gibbs Energy and EMF: $\Delta G = -nFE \qquad \Delta G^\circ = -nFE^\circ$

6. Faraday's Law (mass deposited): $w = ZIt = \frac{MIt}{nF}$

where Z = M/(nF) is the electrochemical equivalent, M = molar mass (g/mol), I = current (A), t = time (s), n = electrons transferred, F = 96500 C/mol

7. Specific conductance: $\kappa = G \times \frac{l}{A} = G \times \text{cell constant} \quad [\text{S/cm}]$

8. Molar conductivity: $\Lambda_m = \frac{\kappa \times 1000}{M} \quad [\text{S·cm}^2\text{/mol}]$

where M = molarity (mol/L)

9. Kohlrausch's law: $\Lambda^\circ_m = \nu_+\lambda^\circ_+ + \nu_-\lambda^\circ_-$

10. Debye-Hückel-Onsager (strong electrolytes): $\Lambda_m = \Lambda^\circ_m - A\sqrt{C}$

11. Degree of dissociation (weak electrolytes): $\alpha = \frac{\Lambda_m}{\Lambda^\circ_m}$

12. Charge-moles relationship: $\text{Charge (C)} = n \times F \times \text{moles of substance}$ $1 \text{ Faraday} = 96485 \text{ C} \approx 96500 \text{ C} = \text{charge of 1 mol } e^-$