Galvanic cell: Chemical energy → Electrical energy. Anode (oxidation) on left; Cathode (reduction) on right. Salt bridge maintains electrical neutrality.
Cell notation: Anode | Anode solution || Cathode solution | Cathode. E.g., Zn | ZnSO₄ || CuSO₄ | Cu. E°cell = E°cathode - E°anode = 0.34 - (-0.76) = 1.10 V.
Standard electrode potential: SHE (Standard Hydrogen Electrode) = 0.00 V by definition. Measured at 25°C, 1 M, 1 atm.
Nernst equation: E_cell = E°_cell - (RT/nF) ln Q = E°_cell - (0.0592/n) log Q at 25°C. At equilibrium, E_cell = 0 and Q = Kc. Therefore: log Kc = nE°_cell / 0.0592.
Electrolytic cell: Electrical energy → Chemical change. External power source forces non-spontaneous reactions. Cathode = reduction (cations deposited). Anode = oxidation.
Faraday's First Law: Mass deposited (m) ∝ charge passed (Q). m = (M × Q) / (n × F). Where M = molar mass, n = valency, F = Faraday = 96,500 C/mol.
Faraday's Second Law: Same charge → masses deposited are proportional to their equivalent weights.
Kohlrausch's law: Λ°_m(electrolyte) = sum of Λ° of individual ions at infinite dilution.
Rate = k[A]^m [B]^n where m, n = partial orders (experimentally determined, not from stoichiometry).
Zero order: Rate = k. t½ = [A]₀/2k. [A] = [A]₀ - kt. Rate independent of concentration.
First order: Rate = k[A]. t½ = 0.693/k. ln[A] = ln[A]₀ - kt. t½ is CONSTANT (concentration-independent). Radioactive decay, H₂O₂ decomposition.
Second order: Rate = k[A]². t½ = 1/(k[A]₀). t½ depends on initial concentration.
k = A e^(-Ea/RT) where A = frequency factor (pre-exponential factor), Ea = activation energy, R = 8.314 J/mol·K.
ln k = ln A - Ea/RT. Plot of ln k vs 1/T: slope = -Ea/R.
Effect of temperature: For every 10°C rise, rate approximately doubles (rule of thumb). Van't Hoff factor: temperature coefficient μ ≈ 2–3.
Catalyst: Provides alternate pathway with lower Ea. Does not change ΔH, ΔG, or equilibrium position — only changes rate by lowering Ea. Increases both forward and reverse rate equally.
R: 8.314 J/mol·K
At 25°C: 2.303RT/F = 0.0592
Nernst: E = E° - (0.0592/n)log Q
SHE: 0.00 V (reference)
First order: t½ = 0.693/k (constant!)
Second order: t½ = 1/k[A]₀
Radioactive: first order (t½ constant)
ln 2 = 0.693
Overall order = m + n
Units of k (0 order): mol/L/s
Units of k (1st order): s⁻¹
Units of k (2nd order): L/mol/s
Specific conductance κ = l/(R×A)
Molar conductance Λ_m = κ × 1000/M
Kohlrausch: Λ° = sum of ionic Λ°
Ostwald dilution law: α = √(Ka/C)
Faraday's law calculations: 1 Q/year
Rate law/half-life: 1–2 Q/year
Arrhenius equation: 1 Q/year
Expected: Units of rate constant → identify order
Watch: Kohlrausch law application