[0:00]Hello, to electrochemistry ka lecture number fourth aur aaj ek chota sa par ek important sa topic lekar hum aa gaye aur wo hai she.
[0:13]She nahi, wo wala nahi, standard hydrogen electrode. Toh main pichle lectures mein bhi baat kar raha tha ki yeh woh electrode hai jisse baaki electrode ka electrode potential determine karte hain. Yeh ek reference electrode hai, yaad aaya? Standard hydrogen electrode. Toh aaj iske bare mein hum padhenge iska concept construction, ismein kaise questions aa sakte hain aur kaise isko use karke jo sabse important hai. Kaise isko use karke aap baaki electrodes ka electrode potential nikal sakte ho, oxidation potential bhi nikal sakte ho aur reduction potential bhi. So my name is Alakh Pandey and this is your cute sa channel Physics Wallah, aayiye heading lagayiye SHE. She se kai log ko yaad aaya. Toh woh nahi hai yeh standard hydrogen electrode, ek khoobsurat si subah mein chalta hua yeh khoobsurat sa topic. Ya isko kai baar NHE bhi bolte hain, normal hydrogen electrode. Toh sabse pehla point ki yeh electrode kaise work karta hai, jaise aap dekhte ho electrode mein kya hota tha ek toh metal rod hota tha. Zinc ke saath zinc sulphate, copper ke saath copper sulphate, ismein aisa nahi hota. Yeh ek different tarah ka hai, it is a gas-ion electrode, yaani yahan pe jo equilibrium hoga woh gas aur ion ke beech mein hoga. Gas lenge hum hydrogen gas aur ion honge H+ ke ion from aqueous solution toh inke beech mein oxidation ya reduction ka process hoga. Gas ion, theek hai. Second point, it is a reference electrode as set by IUPAC. Toh IUPAC ne bola ki bhaiya isko reference electrode maano, kisi bhi electrode ka electrode potential jo hum batate hain woh iske reference mein batate hain. Iske potential ko jab zero maante hain, kiske SHE ke, toh iske reference mein hum bolte hain ki zinc ka reduction potential minus 0.76 volt. Kisse comparison mein? Iske comparison mein, isko zero maan ke, humne aapse bola copper ka reduction potential plus 0.34 volt. Toh uska absolute reduction potential nahi hai. As compared to hydrogen, jab isko zero mana toh iske comparison mein woh 0.34 pe. Very important, abhi aage samjhayenge, reference electrode. Absolute toh nikal hi nahi sakte kisi ka, comparative hi nikalte hain, abhi aage batayenge yeh. Third point, it can act as both anode half cell as well as cathode half cell.
[3:46]Achha, matlab yeh dono taraf se khel khel sakta hai. Oxidation wala bhi, anode bhi ban sakta hai, left hand wala electrode, aur cathode bhi ban sakta hai, reduction, right hand wala electrode, dono ban sakta hai yeh. Chautha point, it's very important, it's standard reduction potential as well as standard oxidation potential is assumed to be zero.
[4:18]Assumed hai, asal mein zero hai ki nahi pata nahi, assume, ek cheez ko zero maan liya, ab iske comparison mein baakiyon ki hum baat kar lenge.
[5:27]Chaliye iska construction dekhte hain, itni point aap note kar lein. Note kar liya?
[5:35]Tere mere milan ki yeh raina, oh tere mere milan ki yeh raina. Toh aayiye iska construction dekhte hain. Construction: Kaise banega yeh? Toh humne yahan pe ek baalti rakh liya isse. Sir vessel bolte hain isko, baalti nahi bolte. Achha, theek hai, vessel rakh liya aur yahan pe ek glass jacket le liya. I have taken a glass jacket over here, there is a slight opening over here in the glass jacket. Yahan pe maine ek glass jacket le liya, ismein ek chhoti si opening hai. Yahan se hum dalenge pure hydrogen gas at one ATM pressure, theek hai. Standard bana rahe hain, standard mein gas kis mein rakhte hain? One ATM pe, achha bahut badhiya. Achha yahan pe gas aayegi aur yahan pe humne le liya maan lo HCl solution, waise toh kuch bhi le sakte ho. Aap HCl solution le lo jiski molarity one M ho, ab bhai HCl dikh raha hai aapko mono basic acid hai, toh ismein se jitna iski molarity hogi. Utna hi molarity H+ dega, toh agar hum puchhe yahan H+ ka concentration kya hai? Toh H+ ka concentration bhi one M ho jayega. Are ismein se ek hi H+ toh niklega na, isiliye yahan pe sulphuric acid wagera nahi liya, usmein se double ho jata hai, toh H+ ki molarity bhi one M. Ekdam hum condition saari standard rakh rahe hain. Temperature maan lo 25 degree Celsius, jabki hum bol rahe hain kisi bhi temperature pe karo, yeh kahani same rehti hai temperature ke liye. Achha toh yahan se bulbul bulbul karke gas aayi, baat yeh hai ki ismein electrode kisko banaye? Bhai gas toh electrode ban nahi sakti, solution ban nahi sakta, electrode jaise pehle hum log khel rahe the zinc wagera mein toh ek metal ka rod tha. Copper ka rod tha, yahan kuch hai nahi, toh yahan pe hum lete hain inert electrode of platinum, aise humne platinum ka taar dal diya. Aise humne platinum ka taar dal diya, yeh. Platinum electrode, wire, inert electrode hai, inert isiliye ki reaction mein participate nahi karega, yahan koi reaction nahi karne lagega. Yahan pe neeche hum lagate hain ek platinum black ki foil. Kya laga diya humne yahan pe? Platinum black ki foil.
[8:24]Abhi dekhenge iska kya kaam hai. Yeh ban gaya saara arrangement for standard hydrogen electrode. Itna note karein, concentration of H+ should be one M, pressure of pure hydrogen gas should be one ATM, jo electrode use kar rahe hain, yaad rakhenge platinum ka hai. Aur glass jacket ke andar kahani ho rahi hai, itni baatein agar aapne kar di platinum black toh yahan pure number mil jane hain ispe, itna hi likhna hai. Theek hai, ab baat aati hai ki iska kya kaam hai, platinum black ka. Dekho yahan se aapne hydrogen gas dalna start kiya, hydrogen gas neeche aayi, aise aapne dabaya yahan se ekdam one ATM pressure pe daba ke bheja, yeh neeche aayi. Ab platinum jo hota hai woh hydrogen ko absorb karta hai, toh theek hai usne hydrogen ko absorb bhi karta hai aur adsorb bhi karta hai, dono hi property hoti hai. Achha, chipka liya hydrogen ko aur jo bachi hui hydrogen thi woh yahan se aise bulbul bulbul karke, aise karke, theek hai, yeh upar chali jayegi aur escape kar jayegi. Jo bhi excess hydrogen jo yeh absorb nahi kar pa raha, adsorb nahi kar pa raha, absorb andar absorb kar lena, adsorb surface pe. Toh woh aise bulbul bulbul bulbul karke bahar nikal gayi. Theek hai, ab kya hoga? Ki is platinum black foil ke aas paas ek toh hydrogen gas iske upar develop hoti ja rahi hai, aur agal bagal H+ ka solution bhi hai. So, ek equilibrium establish hoga hydrogen gas aur H+ ions ka, aur yeh kahan pe? Platinum black pe.
[10:14]Toh yeh hamara cell reaction hai yahan pe, both ways it can go forward or backward, aur usi se do tarah ki cell ban jayegi. Maine likha na it can act as both anode half cell as well as cathode half cell. Aayiye ab dekhte hain dono baatein. Pehla point, SHE as anode half cell, oxidation.
[10:44]Toh bachchon anode pe kya hota hai? Anode pe hota hai oxidation. Toh ismein se woh process utha lo jo oxidation wala hai, oxidation mein kya hota hai? Charge badhta hai. Matlab yeh wala process, yaani H2 will lose two electrons and form 2H+. Yeh oxidation hota hai ki nahi, anode pe oxidation hota hai, toh hydrogen ka dekho oxidation number badh raha hai. Toh is process ka humne kaha ki representation kya hoga? Very important, yeh cheez samajh lo, yahi bachche confuse ho jate hain, exam mein ki kya likha? Are baap re baap, kuchh nahi. Representation, dekho idhar se idhar jana hai toh hydrogen gas kahan pe hai? Platinum electrode pe. Hydrogen gas kahan hai platinum, toh yahan platinum likh dete hain saath mein exam mein, aur bracket mein likhte hain H2 neeche likhte hain H2 ka concentration jaise likh diya P1 atm. Gas ka concentration kis mein hota hai? ATM mein hota hai, theek hai. Jo Nernst equation humne padhi thi usmein humne padha tha ki concentration rakhte hain log 10 P/R, usmein gas ka partial pressure. Toh P1 atm humne 1 atm nahi mana, ho sakta ho kuch aur condition ho, hai na. Jo sawal aaya usmein 1 atm na ho, tab kaise karenge? Yeh ho gaya, ab is taraf yeh kis mein change ho raha hai? H+ mein aur yeh kahan hai? Aqueous form mein in solution. Iska molarity nahi pata let the molarity be CM. Concentration C maan lete hain, C M, 1 M nahi mani humne, humne ideal condition nahi mani. Humne kaha ho sakta ho kuch aur diya ho question karte waqt. Agar aap ekdam standard mein likhoge toh yahan yahan 1 atm likh do, yahan 1 molar, standard mein yahan 1 atm, yahan 1 molar, par main aisa leke chal raha hoon ki exam mein kuch aur likha hai, deta hai sawal. Hai na, Nernst equation lagao, fir iska E nikalo, yeh toh E naught ki baat karne lage na. Achha, is cell ke E naught ki baat karein toh E naught kahan se kahan? H2 se H+, is equals to zero. Yeh IUPAC ne bola, ki iska standard oxidation potential zero.
[12:44]Second baat kar lo, SHE as cathode half cell, reduction. Ab cathode pe kya hota hai? Reduction, cathode half cell. Toh yahan se reduction wala reaction nikal lo, H+ will gain electron and form H2. Yahan pe do laga lo, do laga lo. Iske representation ki baat karein, toh is bar pehle H+ likh lo, aqueous yahan pe likh lo C molar molarity C moles per liter. Fir platinum, H2 gas at P1 atm, ya P2 atm jo bhi likhna ho, kisi pressure pe. Agar hum baat karein idhar ke E naught ki, toh standard reduction potential H+ se H2 yahan half lagana ho laga do kitabon mein likha hota hai, is equal to zero. Yaani SRP bhi zero, SOP bhi zero, just assumed, yeh sab assumption hai, mana gaya ki yeh zero hai. Clear ho gaya? Iska representation ek tarah se aur kitab mein diya rehta hai, dekho darna nahi aise likha hota hai kai baar, platinum slash hydrogen gas at P1 atm slash H+ aqueous at C molar, hai na. Kai baar aise bracket mein likhta hai kai baar slash bana ke aise, H+ aqueous C molar slash platinum, sorry yahan likh dega aise, hydrogen gas slash platinum, kai baar platinum aise slash karke likhta hai, theek hai. Toh usse ghabrane ki ya darne ki koi zarurat nahi hai.
[14:40]Clear hai, toh yeh hai SHE ya NHE, different conditions bhi ho sakti hai, jaise yahan pe humne P aur C le rakha hai. Toh basically toh yahi aata hai paper mein par maan lo achha sawal aa jaye, jara achha sawal karte hain iska hum log, iska ek khoobsurat sa sawal le lete hain, ek do thho.
[15:10]Mita diya jaye? Okay. Ab jara dekho ispe kaise question ban sakte hain, theek hai.
[15:30]Toh standard hydrogen electrode ka potential kitna hai? Zero, chahe oxidation bole chahe reduction bole. Chalo ek question le lete hain, find the electrode potential at 25 degree Celsius for ab dekho ek sawal hum aapko de rahe hain, for H2SO4 aqueous 0.05 molar.
[15:58]Platinum H2, 1 atm. Chalo ab isko karke dikhao, pause karke isko karke dikhao. Batayein iska kya electrode potential aayega, cell reaction apne aap sochein, aur electrode potential nikalein, khud se sochein yeh oxidation hai ya reduction hai. Kya yeh zero hoga ya yeh zero nahi hoga? Sochein. Sochein ab bachcha sochega hydrogen electrode toh zero, aisa thodi na hai. Bhai zero toh tab hota hai jab yahan H+ ka 1 molar concentration hota hai, abhi 1 molar nahi hai kuch aur hai. Dekho ab yahan se isko solve karein, chalo solve karte hain, H2SO4 ki molarity humko de rakhi hai 0.05. Toh bhai sahab jab yeh ions mein aayega manenge ki 100% dissociate kar gaya, pura pura dissociate kar gaya kyunki strong acid hai, very strong acid. Toh yeh two moles of H+ dega ki nahi, toh agar yeh 0.05 hai toh yeh double ho jayega, 2 into 0.05, 2 five ja 10, 1, 0.10 molar, yeh concentration hogi H+ ki. Yaani agar hum H+ ki concentration mangein aapse, toh woh ho jayegi 0.1 molar. Platinum H2, 1 atm. Toh agar yeh 1 molar hoti tab toh aap bol dete zero hai, par yeh toh 0.1 molar hai. Clear na kaise H2SO4 dibasic acid hai, ismein se 2H+ niklenge mana 100% dissociate hua kyunki strong acid hai, toh 0.05 ka double ho gaya. Yeh, ab aapko EMF nikalna hai is cell ka, tab aap Nernst equation use karo, kyunki yeh bhai standard condition toh hai nahi, kya yeh standard condition hai? Nahi. Toh bina standard condition ke liye kya karte hain? Nernst equation, toh E is equals to E naught. Temperature kitna hai? 25, toh hum use kar sakte hain 0.059 by n log base 10 product upon reactant, humne laga di Nernst equation. Ab Nernst equation ke liye half cell ka reaction bhi likho, bhai half hi cell toh hai. Toh H+ se H2 ban raha hai toh H+ plus electrons forms H2. Yahan laga lo two, yahan laga lo two, yahan laga. Kai bachche yahan half likh ke karte hain, unka 100% galat nahi, sahi hai, ha ha. Unka bhi 100% sahi, chahe half lagao, balance kar rahe ho apne aap sab udhar balance ho jayega P aur R mein, sab dikhega abhi dekho kaise. Toh yeh reaction banegi, yahan se aapko n ki value dikhayi pad rahi hai do, do hi electron ka transaction hai. Yaar E naught kya loge? E naught toh zero hoga. Kaun si cell hai? H+ se H2, hai na, toh aap nikal rahe ho E of H+ to H2. E naught H+ se H2, zero hota hai, toh pata hi aapko. Standard oxidation potential hai yeh, hydrogen wale electrode ka zero hota hai, H+ se H2, zero.
[18:55]Toh yeh zero ho gaya, minus 0.059 upon n ki value two rakh dunga, log base 10 product mein kya hai? Hydrogen gas, toh hydrogen gas ka hum lete hain partial pressure, pressure of hydrogen gas upon reactant. Reactant mein kya hai? H+, aur yahan two likha hai toh yeh power mein chala jata hai. Toh H+ ki concentration ka square, concentration ki power two, chalo khatam karte hain. Minus 0.059 by 2 log base 10 partial pressure hydrogen ka 1 atm, toh yahan pe 1 likh lo, atm mein hi rakhte hain pressure. Kisi aur unit mein diya ho toh atm mein change kar lo, bar mein diya ho toh rakh lo, kyunki bar atm kareeb kareeb barabar hote hain. H+ ka concentration apne ko kitna diya hai? 0.1, yaani 10 ki power minus 1 ka whole square, aise likh lein. 0.1, 10 ki power minus 1, toh yeh upar ho jaake ho jayega 10 ki power two. Dekho 10 ki power minus 10 ki power two, fir two bahar aa jayega, minus 0.059 by 2.
[19:54]Log base 10 power two, yahi hoga yeh two yahan se bahar, two se two mar gaya, log 10 to the base 10 is one.
[20:11]Toh yeh ho gaya 1 aur final answer is minus 0.059 volt, toh negative aa raha hai, humne kya matlab, humse toh puchha tha bhaiya electrode potential, theek hai negative. Minus 0.059 volt is the final answer. The final answer for E H2SO4, aise hi likho jaise diya hai, 2. E H2SO4 2 H2 gas, iska concentration kitna bol raha hai apne se? 0.05 aur yeh 1 atm is equals to minus 0.059 volt is the final answer. Theek hai, toh wahi hai standard oxidation ya reduction potential ka istemal karte hain hum beech mein. Clear hai, koi doubt toh nahi hai, ab yahan dekho ek achha sawal ionic equilibrium se laake bana sakta hai JEE advance mein. Woh kya karega H2SO4 nahi dega, tumko acetic acid de diya, pareshan karne ke liye. Kyun acetic acid diya? Kyunki acetic acid puri tarah se ionize nahi hoga. Tab kya karoge aap? Tab aap uska degree of ionization alpha diya rehta tha, yaad hai degree of dissociation alpha? Aur kya diya rehta tha? Ka diya rehta tha. Fir hum dekhte the kitna dissociate hua, H+ ka concentration nikalte C alpha aata. Karte the yeh sab hum? Fir H+ ki concentration utha ke yahan pe rakhte aur tab sawal ko aage badhate. Toh ionic mein yeh cheez aapne padhi thi agar yaad nahi ho toh, kaise H+ ka concentration nikalein in the case of weak acid, yahan weak acid se sawal achha ban jayega. Yahi acetic acid dete toh sawal achha ban jata. Clear hai? Chaliye mitarein?
[21:44]Ab yeh dekh lena na tum, ionic ka lecture mein jana, dekh lena acetic acid mein kaise H+ ki concentration nikalte hain. Wahi change hoga, yahan acetic acid likh dena, 0.05, toh H+ ki concentration nikalna aana chahiye. Chalo dekho ek aur sawal dekho, NCERT ka hai, find the electrode potential at 25 degree Celsius for an electrode.
[22:16]In contact with a solution whose pH is 10, lo bhaiya pH ka sawal bhi aa gaya, ionic aur andar aa gaya ismein, pH wagera se bhi khelne lage.
[22:33]Whose pH is 10. Aise electrode ka electrode potential nikaliye, jo ek solution ke saath contact mein hai, jis solution ka pH 10 hai. Toh hum aisa electrode banane ki koshish karein. Toh humne bana liya platinum slash hydrogen gas, isko 1 atm pe maan lo standard condition. Kis-kiske saath touch mein hai yeh? Ek solution ke saath hai jismein pH 10 hai, achha bachchon. Koi solution hai, yahan kis cheez ka hai pata nahi, is solution ka pH 10 hai, toh yaar pH 10 hone ka matlab kya hota hai? Ki H+ ki concentration 10 ki power minus 10 molar, theek hai. pH kisi ka do hai toh 10 ki power minus 2 molar H+ ki concentration, pH kisi ka char hai toh 10 ki power minus 4. pH kya hota hai? 10 ki power negative mein dal do H+ ka concentration. Theek hai, jaise pH bol deta ek hai toh H+ ka concentration 10 ki power minus 1, pH bolta 7 hai toh H+ ka concentration 10 ki power minus 7, theek hai. 25 degree Celsius pe bola hai, toh ekdam ideal hai, toh H+ le lenge yahan, aqueous, concentration kitni hai? 10 ki power minus 10 molar. Ab batao yeh standard hai kya? Yeh standard hai nahi, toh khatam. E is equals to E naught minus 0.059 by n log base 10 product upon reactant. Ab E kahan se kahan ja rahe ho? Is bar H2 se H+ ja rahe ho, toh yeh bhi ho jayega H2 se H+. Bachchon iski value toh zero ho jayegi aur iske liye reaction likhna padega. H2 se H+ wala reaction likh lo, H2 se 2H+ plus 2 electron, n ki value do ho gayi. Toh minus 0.059 upon n ki value do, log base 10 product kya hai is bar? H+ ki concentration ka square, aur reactant kya hai? Hydrogen, toh partial pressure of hydrogen gas.
[24:36]So, this is minus 0.059 by 2 log base 10, H+ ki concentration 10 ki power minus 10 ka whole square divided by pressure of hydrogen gas is 1 atm. Toh yeh 10 ki power minus 20, fir 20 bahar aa jayega, so this will be minus 0.059 upon 2, 20 bahar aa jayega, minus 20 bahar aa gaya, log 10 to the base 10.
[25:06]Yahi hoga yeh 2 yahan se bahar, 2 se 2 mar jayega, log 10 to the base 10 is one. Toh yeh ho gaya 1 aur final answer is minus 0.059 volt. E of H2SO4, aise hi likho jaise diya hai, 2 H2, iska concentration kitna bol raha hai apne se? 0.05 aur yeh 1 atm is equal to minus 0.059 volt is the final answer. 0.59 volt under this condition jahan H+ ki concentration 10 ki power minus 10 hai. Clear hai? Toh is tarah ke sawal ban sakte the SHE pe, note kar lein. Ab iske baad padhte hain ki SHE ka use kya hai, toh use toh aapne padh liya reference electrode hai, use hota hai kisi aur electrode ka electrode potential nikalne ke liye, par kaise? Kaise? Use of SHE to determine standard electrode potential of different electrodes. Use of SHE to determine standard electrode potential of elements. Elements ka standard electrode potential nikal sakte ho iski help se, aur agar standard ke siwa kuch aur nikalna hai toh Nernst equation use kar lo.
[26:35]Ek baar standard pata chal gaya, toh fir Nernst equation E is equals to E naught minus 2.303 RT by nF log 10 Q. Q, quotient reaction quotient, product upon reactant, wahan se bhi nikal jayega. Standard yeh nikal ke de denge, theek hai. Toh dekho baat yeh thi ki single electrode ka electrode potential aap nahi nikal sakte, you can never find absolute potential of single electrode.
[27:14]Kisi ek electrode ka koi absolute potential aap nahi nikal sakte, reason suno ki are ek electrode ko solution mein daloge toh kya hoga? Bhai ya toh electrode pe positive aayega solution pe negative ya isi ka ulta, electrode pe negative solution pe positive, charge toh develop honge. Par current hi flow nahi karega bhai ek hi electrode hai kahin se wire hi connected nahi hai. Jab current flow nahi karega toh potential difference kaise pata chalega? Difference nikalne ke liye do half cell ka hona zaruri hai, kisi single electrode ka electrode potential nahi nikal sakte. Single electrode daloge toh kya hoga? Ya toh oxidation hoga ya toh reduction hoga. Toh ek process se thodi na nikal paoge, yeh oxidation reduction complementary process hai, saath mein hote hain. Toh idhar oxidation ho raha tha toh udhar kahin reduction hoga, jab dono ko jodoge tab potential difference. Hai na, toh jitna bhi electrode potential hum batate hain, kisi se compare karke, absolute nahi hota. We find relative electrode potential with respect to standard hydrogen electrode.
[28:20]SHE ka aapne kya kiya? E naught H+ se H2 ko zero assume kar liya. E naught H2 se H+ ko bhi zero assume kar liya. Ab iske comparison mein aap kisi ko bata sakte ho. Ab dekho, connect the given electrode as anode half cell or cathode half cell with SHE.
[28:57]Ab jo bhi given electrode hai jiska electrode potential nikalna hai, usko ya toh anode half cell banao, ya toh left side mein laake connect karo SHE se, ya cathode half cell right side mein connect karo, koi tension nahi hai, dono se nikal aayega. Dono se nikal aayega, koi tension nahi, kya nikal paoge uska? Standard electrode potential, baki koi electrode potential nikalna hai toh Nernst equation hai. Standard nikalne ke liye aap use karo SHE ko. Toh kaise use karenge? Jara note kar lein fir batayein. Note kar liya? Mita dein?
[29:33]Mita dein? Anode banake bhi connect kar sakte hain aur cathode, aapne padha na, SHE toh anode bhi ban sakta hai cathode bhi. Chalo hum log zinc ka nikalte hain, example le lete hain ki humein zinc ka standard reduction ya standard oxidation potential ya dono nikalna hai. Zinc se Zn2+ ya jaisa likhna chahe koi naraj ho raha hai, Zn2+ se Zn, yeh ho gaya reduction, yeh ho gaya oxidation. Dono aa jayega ek hi reaction se, ek hi experiment se. Hum ek kaam karte hain, hum zinc ko anode half cell banate hain, humari marzi, anode bhi bana sakte hain aur cathode bhi, koi dikkat, koi tension nahi. Toh left hand side mein main zinc wala pura system banaunga, yahan pe solution le liya, solution mein zinc sulphate ion le liya, iska concentration 1 molar le liya. Jisse zinc ke ions 1 molar mein honge, yahan ek electrode dal diya, kis ka electrode dalenge? Zinc ka dalenge, zinc rod. Zinc rod le liya, bahut badhiya. Achha, yahan se ek taar laga ke ek voltmeter laga ke connect karenge SHE se, theek hai. Toh yahan pe SHE banayenge hum.
[31:00]Yeh black platinum humne laga diya platinum foil, yahan se hum kya dalenge? Yahan se hum dalenge pure hydrogen at 1 atm, etc, etc. Yahan pe hum HCl ka solution le liya 1 molar ka, jisse H+ ka concentration bhi 1 molar ho gayi, yeh ho gaya hamara SHE. Yeh zinc rod ho gaya, woh hamara platinum electrode. Yahan se. Theek hai, yeh black platinum humne laga diya platinum foil, yahan se hum kya dalenge? Yahan se hum dalenge pure hydrogen at 1 atm wagera wagera jitni kahani karni thi. Yahan pe hum HCl ka solution le liya 1 molar ka, jisse H+ ka concentration bhi 1 molar ho gayi, yeh ho gaya hamara SHE. Theek hai, ab humne bana liya kya? Anode, aur isko humne bana liya cathode, theek hai, humne jaan bujh ke left pe lagaya. Ab bachchon anode banaya toh yahan pe oxidation hoga, toh kya reaction hoga? Ki zinc yahan se bahar nikal ke aayega in the form of Zn2+. Yaani zinc will change to Zn2+ plus 2 electron. Isko cathode bana liya toh yahan pe reduction hoga. Yahan se dekho electron, Zn2+ niklega, electron ispe chhodta jayega, zinc se rod se Zn2+ nikla electron chhodta gaya, yeh electron yahan gaye, aur yahan pe reduction, toh hydrogen. Sorry, H+ will accept these electron and form H2. Cathode pe reduction ho gaya, anode pe oxidation, yahan se Zn2+ nikla yeh electron nikle idhar gaye, yahan pe H+ ion ne electron gain karke H2 form karke iske upar chipakta gaya hydrogen gas, toh yeh reactions ho rahe hain do half cell mein. Achha hum yeh sara experiment agar saja dein 25 degree Celsius pe toh puri condition dekho standard ho gayi. Agar yahi experiment 25 degree Celsius pe karoge toh dekho zinc ka aapne concentration 1 molar le rakha hai, zinc rod le rakha hai, hai na. Yahan pe hydrogen ka concentration aapne 1 atm le rakha hai, H+ ka concentration 1 molar le rakha hai, pressure matlab gas jo hai uska pressure 1 atm hai, concentration of ion 1 molar hai, aur temperature 25. Yaani puri aapne standard conditions saajh rakhi hai. Is time maan lo voltmeter ki kuch deflection aaya, voltmeter ka potential difference aaya, let us say, isne show kiya, let us just assume, let us say it shows X aa rahi hai iski reading, kitni aa rahi hai? X aa rahi hai. Toh is time yeh kya dikha raha hai? E of cell ki E naught of cell? E naught of cell, kyunki condition saari standard hain. Toh yahan se aapko ek cheez samajh mein aa gayi ki is pure reaction ke liye E naught of cell is equals to X volts. Yeh humne kaha ki dikha humne na, yeh experiment se humne dekha, observe kiya. Ab humne dimag lagaya ki iska E naught hum kya likhte hain? Bachchon E naught of cell kya hota hai? E naught of cell hota hai E naught of cathode minus E naught of anode. Kai log soch rahe hain E naught kaise likh diya sir ne? Are sari condition maine standard li toh main E naught hi toh likhunga. E naught of cell is X, cathode pe yeh hain bhaiya, toh inke liye E naught, ab batao cathode ka reaction kya likhoge yahan pe matlab yahan pe representation? H+ se half H2 minus E naught, achha yahan pe kaun sa potential likhte hain? Reduction yaad hai na? E naught of cell, E naught of cathode ka bhi reduction potential, anode ka bhi reduction potential, yeh nahi ki yahan pe Zn se Zn2+ reaction dekh ke aisa nahi ki hai na.
[34:23]Bawle ho gaye, nahi yahan bhi reduction potential, yaani Zn2+ se Zn.
[34:34]Ab dekho yeh X hai, iski value zero ho gayi minus E naught Zn2+ se Zn. Toh aapko zinc ka dekho standard reduction potential mil gaya.
[34:48]Aapko zinc ka E naught Zn2+ se Zn ki value minus X, aur X aapne note kar liya tha aur X ki value aayegi yahan pe 0.76 volt. Agar experiment karenge aur zinc ka standard reduction potential minus 0.76 volt. Ab bologe sir yeh toh bhaiya kya hai? Standard reduction potential.
[35:42]Kehta nahi humko standard oxidation chahiye E naught Zn se Zn2+ humko chahiye. Standard oxidation potential toh yeh plus X ho jayega bhai.
[36:00]Ek nikal lo toh anode banake connect kar lo, ek nikal lo dusra palat ke, yeh yaad rakhna ki E naught of cell mein dono ka reduction potential likhte hain. Toh yeh tarika tha kisi bhi electrode ka standard electrode potential ya standard reduction nikal lo fir oxidation nikal aayega, aur baaki kuch nikalna hai toh Nernst equation. Toh yahan pe is lecture ko SHE ko hum khatam karte hain, padhai karte rahein all the very best.
