⚡ Electrochemistry – Quick Revision Notes (IIT JEE)

⚖️ 2. Nernst Equation (Very Important)

At 298 K: $E_{cell} = E^\circ_{cell} – \frac{0.0591}{n} \log Q$Ecell​=Ecell∘​−n0.0591​logQ

👉 Used for:

• Non-standard conditions
• Finding concentration / EMF

🔄 3. Concentration Cell

• $E_{cell} = \frac{0.0591}{n} \log \frac{C_1}{C_2}$Ecell​=n0.0591​logC2​C1​​

⚡ 4. Faraday’s Laws of Electrolysis

1st Law:

$W = ZIt$W=ZIt
👉 Mass ∝ charge passed

2nd Law:

• $\frac{W_1}{W_2} = \frac{E_1}{E_2}$W2​W1​​=E2​E1​​

💧 5. Conductance

Conductivity:

• $k = \frac{1}{R} \times \frac{l}{A}$k=R1​×Al​

Molar Conductance:

• $\Lambda_m = \frac{k \times 1000}{C}$Λm​=Ck×1000​

Equivalent Conductance:

• $\Lambda_{eq} = \frac{k \times 1000}{N}$Λeq​=Nk×1000​

📉 6. Kohlrausch’s Law

• $\Lambda_m^\circ = \lambda^+ + \lambda^-$Λm∘​=λ++λ−

👉 Important for weak electrolytes

🔬 7. Extra Concepts

Debye-Hückel-Onsager Equation:

• Conductance decreases with concentration

Fuel Cell:

• $E_{cell} = E^\circ_{cathode} – E^\circ_{anode}$Ecell​=Ecathode∘​−Eanode∘​

Corrosion:

• Rate depends on current and environment

🎯 Quick Tips for JEE

• Nernst equation → Most important
• Practice numericals on:
  • EMF
  • Electrolysis
  • Conductance
• Remember:
  Anode = Oxidation, Cathode = Reduction

🧠 Memory Trick

👉 “AN OX, RED CAT”

• Anode → Oxidation
• Cathode → Reduction