Ye notes Class 12 Chemistry ke Chapter 3 'Electrochemistry' par based hain. Yahan hum electrochemical cells, electrolysis, conductance, Nernst equation aur Faraday ke laws ko simple language mein samjhenge. Ye notes NCERT syllabus ke mutabik tayar kiye gaye hain taaki aapko exam ke liye madad mile.
Electrochemical cell wo device hai jo chemical energy ko electrical energy mein convert karta hai (voltaic cell) ya phir electrical energy se chemical reaction karvata hai (electrolytic cell). Voltaic cell mein spontaneous redox reaction hoti hai, jabki electrolytic cell mein non-spontaneous reaction ko force kiya jata hai.
Galvanic cell mein do electrodes hote hain: anode (oxidation) aur cathode (reduction). Salt bridge dono half-cells ko connect karta hai aur charge balance maintain karta hai. Cell representation: Zn | ZnSO4 || CuSO4 | Cu.
Cell potential ko E° cell = E° cathode - E° anode se nikalte hain. Standard hydrogen electrode (SHE) reference electrode hai jiska potential 0V hota hai. Nernst equation se non-standard conditions par cell potential nikalte hain:
E = E° - (RT/nF) ln Q
Yahan R gas constant, T temperature, n electron mole, F Faraday constant, Q reaction quotient.
Nernst equation ka upyog equilibrium constant (Kc) aur Gibbs free energy change (ΔG) nikalne mein hota hai. Relation: ΔG° = -nFE° aur ΔG = ΔG° + RT ln Q.
Electrolytic solutions mein current flow unke ions ke movement se hota hai. Conductance (G) = 1/R. Molar conductivity (Λm) = κ × 1000 / C, jahan κ specific conductivity, C concentration. Kohlrausch law ke anusar infinite dilution par molar conductivity unke ions ki individual contributions ka sum hota hai.
Λ°m = ν+ λ°+ + ν- λ°- , yahan ν stoichiometric coefficient, λ° ionic conductivity at infinite dilution. Isse weak electrolytes ki dissociation constant (Ka) nikalne mein madad milti hai.
Electrolysis mein electric current pass karne par electrolyte ke ions electrode par discharge hote hain. Faraday first law: mass of substance deposited (m) ∝ charge (Q). Second law: different substances ke liye same charge equal equivalents produce karta hai. Formula: m = (M × I × t) / (n × F), jahan M molar mass, I current, t time, n valence, F=96500 C/mol.
Electroplating, metallurgy (Al extraction by Hall-Heroult process), aur electrolytic refining iske practical uses hain.
Primary batteries (e.g., Leclanche cell) rechargeable nahi hote, secondary batteries (e.g., lead-acid battery) rechargeable hote hain. Fuel cells (e.g., H2-O2 cell) continuous fuel supply se electricity dete hain. They have high efficiency and low pollution.
Ye notes NCERT class 12 chemistry chapter 3 ke important concepts ko cover karte hain. Inhe dhyan se padhein aur numerical practice karein. Sabhi formulas aur definitions yaad rakhna na bhoolen.
