CHEMCA
EXAM MASTER FORMULA SHEET
Electrochemistry
High-Yield Revision for JEE Main, Advanced & NEET
1. Electrolytic Conduction
Resistance & Conductance:
\[ R = \rho \frac{l}{A} \quad | \quad G = \frac{1}{R} = \kappa \frac{A}{l} \]
Cell Constant (\(G^*\)) = \(l/A\)
Molar Conductivity (\(\Lambda_m\)):
\[ \Lambda_m = \frac{\kappa \times 1000}{M} \]
Unit: \(S \cdot cm^2 \cdot mol^{-1}\)
Kohlrausch's Law (Independent Migration):
\[ \Lambda_m^\circ (A_xB_y) = x \lambda_m^\circ (A^{y+}) + y \lambda_m^\circ (B^{x-}) \]
Degree of Dissoc. (\(\alpha\)): \[ \alpha = \frac{\Lambda_m}{\Lambda_m^\circ} \]
Dissoc. Constant (\(K_a\)): \[ K_a = \frac{C \alpha^2}{1-\alpha} \]
2. Laws of Electrolysis
1st Law:
\[ w = Z \cdot I \cdot t = \frac{E \cdot I \cdot t}{96500} \]
\(Z\) = Electrochemical Equivalent
2nd Law:
\[ \frac{w_1}{w_2} = \frac{E_1}{E_2} \]
\(E\) = Equivalent Weight
1 Faraday (F): Charge of 1 mole of electrons \(\approx 96500 \text{ C}\)
3. Electrochemical Cells
Cell Potential (\(E_{cell}\)):
\[ E_{cell}^\circ = E_{cathode}^\circ - E_{anode}^\circ \quad \text{(Both as SRP)} \]
Nernst Equation:
\[ E_{cell} = E_{cell}^\circ - \frac{2.303 RT}{nF} \log Q \]
At 298 K:
\[ E_{cell} = E_{cell}^\circ - \frac{0.0591}{n} \log Q \]4. Cell Thermodynamics
Gibbs Free Energy:
\[ \Delta G = -n F E_{cell} \]
\[ \Delta G^\circ = -n F E_{cell}^\circ \]
Equilibrium Constant (\(K_{eq}\)):
\[ \log K_{eq} = \frac{n E_{cell}^\circ}{0.0591} \]
Temp. Coefficient:
\[ \Delta S = nF \left( \frac{dE}{dT} \right)_P \quad | \quad \Delta H = -nFE + nFT \left( \frac{dE}{dT} \right)_P \]
5. Concentration Cells & Misc
Concentration Cell:
Same electrodes, different concentrations (\(E_{cell}^\circ = 0\))
\[ E_{cell} = \frac{0.0591}{n} \log \frac{C_{cathode}}{C_{anode}} \]Corrosion (Rusting)
Anode: \(Fe \to Fe^{2+} + 2e^-\)
Cathode: \(O_2 + 4H^+ + 4e^- \to 2H_2O\)
Reference Electrode
SHE (\(E^\circ = 0.00 \text{ V}\))
No comments:
Post a Comment