ELECTROCHEMISTRY CLASS 12 SHORT NOTES NEET TOPPER

 चलो हम Class 12 Electrochemistry का एकदम teacher-style summary करते हैं — NEET के हिसाब से important concepts के साथ:

---

📘 Electrochemistry – NEET-Focused Summary

---

🔹 1. Electrochemical Cell (Voltaic/Galvanic Cell)

• Converts chemical energy → electrical energy

• Based on redox reactions (oxidation at anode, reduction at cathode)

• Anode is negative, cathode is positive

• Example: Daniel cell (Zn | Zn²⁺ || Cu²⁺ | Cu)

NEET Tip: EMF calculation, cell representation, and identifying anode/cathode are frequently asked.

---

🔹 2. Electrolytic Cell

• Converts electrical energy → chemical energy

• Non-spontaneous reactions

• Anode is positive, cathode is negative

• Example: Electrolysis of molten NaCl

---

🔹 3. Electrode Potential

• Tendency of an electrode to lose or gain electrons

• Standard electrode potential ($E^\circ$) measured under 1M, 1atm, 25°C

🔸 Standard Hydrogen Electrode (SHE)

• Reference electrode, $E^\circ = 0$ V

NEET Tip: Higher $E^\circ$ → better oxidizing agent, lower $E^\circ$ → better reducing agent

---

🔹 4. EMF of Cell

$$E^\circ_{cell} = E^\circ_{\text{cathode}} - E^\circ_{\text{anode}}$$

• If $E^\circ_{cell} > 0$ → cell reaction is spontaneous

---

🔹 5. Nernst Equation

For non-standard conditions:

$$E = E^\circ - \frac{0.0591}{n} \log Q$$

At equilibrium:

$$E_{cell} = 0 \Rightarrow E^\circ = \frac{0.0591}{n} \log K$$

NEET Tip: Formula-based MCQs are common – learn to plug values quickly.

---

🔹 6. Electrochemical Series

• Arrangement of elements by their standard reduction potentials

• Used to predict feasibility of redox reactions

---

🔹 7. Conductance of Electrolytic Solutions

• Kohlrausch's Law: $\Lambda_m^\circ = \lambda^\circ_+ + \lambda^\circ_-$

• Important for calculating molar conductivity and dissociation constants

---

🔹 8. Faraday’s Laws of Electrolysis

First Law:

$$m = ZIt \quad \text{(Z = electrochemical equivalent)}$$

Second Law:

• Masses of substances liberated are proportional to their equivalent weights

---

🔹 9. Batteries and Fuel Cells

• Primary cell: non-rechargeable (Dry cell)

• Secondary cell: rechargeable (Lead storage battery)

• Fuel cell: converts chemical energy directly into electricity (e.g., H₂-O₂ fuel cell)

---

🔹 10. Corrosion

• A redox reaction

• Rusting of iron is a classic example

---

⚠ NEET Important MCQ Focus:

• Nernst equation

• Cell notation & EMF

• Electrochemical series logic

• Faraday's law application

• Numericals on $E^\circ_{cell}$, $K_{eq}$, and $\Lambda_m^\circ$

---