Vidyut Rasayan (Electrochemistry) Notes - Class 12

These notes? They’re here to walk you through electrochemistry, from the absolute basics all the way up to the more advanced stuff. We’re following the NCERT line, so expect to get a real handle on electrochemical cells, how conductance actually works, the ins and outs of electrolysis. Faraday’s laws too.

Main Topics Covered:

• Electrochemical cells — galvanic cells? Yeah, we dig into both.
• Alright, let’s get straight into the heart of it. We’re talking about the Nernst Equation and Cell Potential—the stuff that basically tells you which way a reaction wants to go and how much juice it can actually deliver. We break down the equation itself, piece by piece, so you’re not just memorizing it but actually getting why it works. Then we look at how cell potential shifts when conditions aren’t standard—temperature changes, concentrations moving around, that kind of thing. You’ll see how the math connects directly to real electrochemical cells. We make sure you can calculate what’s going on in a system without getting lost in the symbols. It’s practical, it’s grounded, and it’s the kind of material that clicks once you see the logic behind it.
• Alright, here’s the rewrite, keeping it punchy and human under that “Main Topics Covered” heading. --- How electrolytes actually conduct electricity. We’ll break down what makes them tick and why they behave the way they do.
• Here’s a tightened, more human take: Faraday’s Laws of Electrolysis—this is where we dig into the real nuts and bolts of how electrolysis actually works. You’ll get a clear handle on the first law. Ties the amount of substance liberated at an electrode straight to the quantity of electric charge passed through the electrolyte. Then there’s the second law, which brings in equivalent weights and shows how different substances relate to each other when the same charge flows. We walk through the math step-by-step, so the formulas don’t just sit there as abstract symbols—you see them do something. And along the way, we touch on the practical side too: what these laws mean in real electroplating or refining setups, and where they hold up or start to bend.
• Batteries and fuel cells—yeah, we’re digging into both of those.

Here we have provided NCERT notes for Class 12 रसायन विज्ञान in hindi Language, Just select the chapters below to get notes of the same:

ठोस अवस्था

विलयन

वैधुत रसायन

रासायनिक बालगतिकी

पृष्ट रसायन

तत्वों के निष्कर्षण के सिद्धांत एवं प्रकम

pand ब्लॉक के तत्त्व

dand एवं fand ब्लॉक के तत्त्व

उपसहसंयोजन यौगिक

हैलोजन व्युत्पत्र

ऑक्सीजन युक्त क्रियात्मक समूह

एल्डिहाइड कीटोन और कार्बोक्सिलिक एसिड

नाइट्रोजन युक्त क्रियात्मक समूह वाले कार्बनिक यौगिक

जैव अणु

बहुलक

त्रिविम रसायन

दैनिक जीवन मे रसायन

विशेष अध्याय

Electrochemical Cells

Electrochemical cells are basically the go-betweens for chemical and electrical energy. They either take chemical energy and turn it into electricity, or they flip the whole thing around and use electricity to force a chemical reaction. You’ve got two main kinds here. First, there are Galvanic—or Voltaic—cells, and these are the ones that just do their thing naturally. A spontaneous reaction happens, and boom, you’ve got electrical current flowing out. Then you’ve got electrolytic cells, which are a different story altogether. These need an external power source to push a reaction that wouldn’t happen on its own. Without that outside juice, nothing’s moving.

Galvanic Cell Structure

Ek typical galvanic cell mein do half-cells hote hain—ek anode, jahan oxidation hoti hai, aur ek cathode, jahan reduction hoti hai. Yeh dono half-cells ek salt bridge ke through judte hain, jo ion flow ko maintain karta hai. Socho, jaise Daniell cell mein hota hai: zinc anode ka kaam karta hai, aur copper cathode.

Nernst Equation

Nernst equation ka poora point yeh hai ki cell potential kisi bhi concentration pe kaise behave karta hai. Formula simple hai: Ecell = E°cell - (RT/nF) ln Q. Jab aap standard temperature yaani 298K pe kaam karte ho, toh yeh equation aur bhi seedha ho jaata hai — bas (0.0591/n) log Q wala form aata hai. Aur sabse acchi baat? Isi equation se aap pH tak nikaal sakte ho, aur equilibrium constant bhi mil jaata hai. Koi jhanjhat nahi.

Conductance of Electrolytes

Electrolytic solutions ki conductance ka poora khel inke ions par hi chalta hai—jitne zyada ions honge, aur jitni tezi se woh move karenge, utni hi behtar conductance milegi. Do terms hain jo sabse zyada matter karti hain: specific conductance (κ) aur molar conductance (Λm). Aur yahan ek interesting baat hai—jaise hi aap solution ko dilute karte hain, molar conductance upar chadhne lagta hai, bilkul waisa hi jaisa Kohlrausch's law batata hai.

Kohlrausch's Law

Kohlrausch’s law basically says that at infinite dilution, the molar conductance of an electrolyte is just the sum of what its individual ions bring to the table. You write it as Λ°m = λ°+ + λ°-, which sounds fancy. It’s really just addition. The neat part? This law lets you figure out the dissociation constant for weak electrolytes, which is a pretty big deal since those don’t fully break apart in solution. So you’re not just looking at numbers—you’re actually unlocking how much a weak acid or base splits up.

Faraday's Laws of Electrolysis

Faraday ke do hi laws hain—koi teen nahi, koi chaar nahi. Pehla law seedha sa hai: electrolysis ke dauran jo bhi mass deposit ya dissolve hota hai, woh current aur time ke saath seedha proportional chalta hai. Matlab, m = ZIt, jahan Z ko electrochemical equivalent kehte hain. Aur doosra law thoda alag angle se aata hai—agar aap same quantity of charge ko alag-alag electrolytes se guzarte hain, toh jo masses deposit honge, woh unke chemical equivalents (E) ke ratio mein hi milenge. Simple si baat hai, lekin samajhne wali zaroor hai.

Applications of Electrolysis

• Electrorefining’s where metals like copper really get their glow-up. You take impure copper, run a current through it, and the pure stuff collects on one side while the junk just falls away. It’s not flashy. It’s how you get the good-quality metal for wiring and electronics. Copper refining’s the classic example—dirty anode, clean cathode, and all the impurities either dissolve or drop out as sludge. Honestly, it’s a neat trick that keeps industry running without wasting much.
• Here’s a rewrite that fits the “Applications of Electrolysis” heading, keeps the facts straight. Sounds like a real person talking: Electroplating is one of the most common uses of electrolysis you’ll actually see in the real world. Think about gold or silver coating—that’s not just dipping something in shiny paint. The process uses an electric current to deposit a thin layer of metal onto another surface, usually to make it look better or to stop it from rusting. You might not realize it. Your jewelry, your cutlery, even some car parts have been through this. It’s clever, it’s practical, and it’s all thanks to the same basic chemistry happening inside an electrolytic cell.
• The chlor-alkali process is where the real heavy lifting happens. It churns out chlorine and sodium hydroxide, two chemicals you’ll find everywhere. It’s one of those industrial workhorses that quietly powers a ton of stuff we use daily.

Batteries aur Fuel Cells

Batteries, asli mein, multiple galvanic cells ka combination hote hain—bas yahi unki basic identity hai. Ab baat karein types ki: primary batteries, jaise dry cell, ko aap recharge nahi kar sakte, bilkul nahi. Lekin secondary batteries, jaise lead storage battery ya Ni-Cd, ko baar-baar charge kiya ja sakta hai. Phir aate hain fuel cells—ye alag hi level pe kaam karte hain. Inhe continuous supply chahiye hoti hai fuel aur oxidant ki, aur isi se electricity generate hoti hai. Hydrogen-oxygen fuel cell iska best example hai, kyunki isme by-product ke roop mein sirf water milta hai. Simple, hai na?

Corrosion

Corrosion, asli mein, ek electrochemical process hai—metal apne hi compounds mein convert ho jata hai, bilkul waise hi jaise iron ka rusting. Iske liye oxygen aur moisture dono ka hona zaroori hai, warna baat hi khatam. Aur haan, isko rokne ke liye galvanization (matlab zinc coating) ya phir cathodic protection ka sahara liya ja sakta hai, aur ye kaafi kaam ki cheezein hain.

Yeh notes aapke Class 12 Chemistry ke Electrochemistry chapter ki taiyari mein kaafi kaam aayenge. Bas practice karte raho, aur numerical problems ko solve karte raho. Sab kuch acche se cover ho jayega.