[0:00]Hello my lovely students, so most awaited topic jo hai colligative property ka wo aa chuka hai. Isme hum colligative properties ke baare me baat karenge, to jo colligative words hai, wo kaha se liya gaya hai? It is from the Latin. Theek hai, Latin jo bhasha hai usse hamara colligative word liya gaya hai, jiska meaning hota hai co ka meaning hota hai together and ligare ka matlab hota hai bind. That means colligative hua jo ki bind together. Theek hai, ab isko main explain karungi yaha niche. Sabse pehle aapko samjhna hoga jo colligative properties hoti hai, uske four aapki properties hoti hai, jinhe ki colligative kaha jata hai. First hai aapki relative lowering of vapour pressure, theek hai, second hoti hai aapki depression of freezing point, third one is the elevation of boiling point and fourth one is the osmotic pressure, okay? These four are the colligative properties. And ab aapke man mein question aayega what is meant by the colligative properties? Ki ye aisa kya isme hota hai ki ye colligative properties kahlati hai? So, coming to the definition, colligative property kya hoti hai? Colligative properties depend on the number of solute particles irrespective of their nature. Colligative property jo bhi hum kahenge ki jaise ye charo colligative property hai, uska matlab kya hota hai ki wo jo properties hai, wo sirf aur sirf number of solute particles ke upar depend karti hai. Na hi wo kisi other kisi aur factor pe depend karti hai, na wo nature pe depend karti hai. Sirf aur sirf wo kis pe depend karti hai? Number of solute particles par depend karti hai and aapko viva mein jo practical mein aapka viva lete hai, usme bhi most of the time ye pucha jata hai colligative property kis pe depend karti hai? Colligative property wo hoti hai jo number of solute particle pe jo depend karti hai, to aapne sirf ye wali baat yaad rakhni hai isme, theek hai. And irrespective of their nature, nature se usme koi uska role nahi hai, sirf number of solute particles kitne hai usse wo badhti ya ghati hai colligative property ki value, theek hai. Colligative means jaise humne pehle kara ki according to the Latin language, iska matlab hota hai bound together. Ab bound together is colligative property mein hume kaise dekhne ko milega? It refers to how the properties of solvent are bound to the concentration of solute in solution. Matlab colligative property bound together meaning hai iska kyu? Kyunki aap dekh sakte ho ki kis tarah se number of jo solute particles hai usse bound hai aapki pure ki puri ye colligative property, theek hai. Isiliye bound together isiliye iska naam colligative humne Latin word, theek hai. Ab isme jo aapka among the four jo colligative property hai, we will study the first one, that is relative lowering of vapour pressure. Theek hai, ab colligative property agar koi puche isme yaha pe confuse ho jaate hai bacche ki vapour pressure agar sirf vapour pressure puche, is it a colligative property? No, it is not a colligative property. But the relative lowering of vapour pressure is the colligative property. Agar pucha jaye relative hata do, agar pucha jaye lowering of vapour pressure hai kya colligative property? You will say no, it is not a colligative property. Pura ka pura hona chahiye R L V P matlab relative lowering of vapour pressure hi aapka colligative property ke under aata hai, not the only vapour pressure. Theek hai, ab dekho baat karte hai, vaise ye hamara jo Raoult's Law padhaya tha maine playlist mein check karna, uska jo case two karvaya tha wo bhi relative lowering of vapour pressure hi karvaya tha.
[3:39]Isko dobara se main acche tarike se yaha pe samjha deti hu with aapke pass ki kon kon se aapke pass formulas use ho gaye jisse aap numerical easily kar paoge, okay? To first one is the relative lowering of vapour pressure. Ab dekho, usko samjhne ke liye humne kya liya hai yaha par? Ek scenario humne lena padega, jisme ki pure A matlab A kya hai aapka yaha pe solvent hai aur ye aapka solute hai. Ab aapko ek volatile solvent lena padega aur ek non-volatile solute lena padega. To relative lowering of vapour pressure mein pehle to aap yaad, criteria kya yaad rakhoge? Ki ek pure aapka solvent hai, pure liquid A hai aapka, that means solvent hai. Uske upar jo ki volatile hai, volatile ka matlab kya hota hai? Jiski easily vapours ban jate hai. To usme kya hai? Usme hum daal rahe hai non-volatile solute daal rahe hai, theek hai? Non-volatile solute ka kya matlab hai? Aisa matlab hoga kya ye non-volatile hai to that means ye solid form mein hoga matlab jiske vapours nahi ban sakte. Agar chahe aap jitna bhi heat karo jo non-volatile hoga, uske kabhi bhi wo ud ke vapour mein nahi jayega, wo solid ka solid ya fir wo solution mein vaise ka waisa hi rahega. Jab aapne in dono ko mix kara, solvent and solute ko jab aapne mix kara to aapke pass ek solution mil gaya, solution ban gaya. Aur aapne dekha jo pure A tha, pure solvent tha, agar usme sirf A ke hi particles hai to aapko dikhega ki yaha pe aapko molecule jo layer mein dikhege, wo pure A-A ke dikhege. Aur inki wajah se jab ye vapour form mein jayegi inki wajah se jo pressure hoga, usko humne denote kiya PA not se. Aur abhi tak to aap ye samajh gaye hoge ki jab bhi not laga ho, that means it represent the pure state, theek hai? Ab yaha par kya hoga? Ye to non-volatile solute hai, isiliye iski wajah se na pure mein koi pressure hoga na solution mein koi pressure hoga, kyunki ye jab vapour banayega hi nahi to vapour pressure kaha se exert karega? To na ye vapour banata hai, na inke regarding koi vapour pressure hoga. Jab ye solution mein banaye gaye dono mix karke solute and solvent to aapko is tarah ki cheez dekhne ko milegi. Ab kya hoga? Because yaha pe B jo hai non-volatile solute bhi hai to humne ye jo layer banayi hai usme A ke molecule bhi hai aur sath hi sath aapke B ke bhi molecule hai. Aur aapki jo evaporation honi hai, wo aapki evaporation yahi se honi hai matlab yahi isi layer pehle layer by layer evaporate hoti hai na. To jo sabse pehli layer hai ussi se aapke vapours banne hai, to aap kya dekhoge ki yaha par jo vapours banenge only A ke banenge. B ke nahi banenge, kyu nahi banenge? Kyunki B is the non-volatile solute hai, volatile nahi hai isliye iske vapour nahi banenge. A aapko ye jo vapours jiske bhi dikh rahe hai, wo aapka A component hai, to isiliye inke jo solution phase mein A ke jo vapours aayenge, usko hum denote karenge PA se. Aa gayi baat samajh? Aur vaise bhi aap yaha par dekh sakte ho jo pure A hai, uska jo pressure PA not hai aur jo yaha pe A component hai solution mein uska pressure hai PA. Ab batao dono mein se konsa jyada hoga pressure? To obviously hamara hamesha yaad rakhna jo pure ka hai, pure ka hamesha vapour pressure jyada hota hai than that in the solution, uska vapour pressure in the solution. Aisa kyu hota hai? Kyunki pure A mein kya hota hai? A ke hi particles hote hai, theek hai. To wo jab evaporate karenge, easily evaporate karenge, bahut jyada evaporation hoti hai pure A ke case mein, kyunki inko disturb karne wala koi dusra component nahi present hai, theek hai? Sabke sab ek hi tarah ke hai aur wo easily vapour banayenge, isiliye PA not ki value jyada ho jayegi. On the other hand solution hai, solution mein aapke paas B wale particle bhi hai. Ab kya kar, kya baat ho rahi hai? Jahan aapko jagah A ne leni thi waha B aapke jagah le rahe hai aur yaha se wo kya kar rahe hai? Yaha se wo evaporation ko kam kar rahe hai. Theek hai, hindrance badha rahe hai kyunki yaha pe A particle aana tha, theek hai, A ki jagah B aa gaya aur B kya hai? B non-volatile hai. B to vapour bana hi nahi sakta, isiliye A ke bhi vapour kam banenge as compared to its pure state. Isiliye PA aapka less ho jayega as compared to the pure. Isiliye kya hota hai ki jo pure ka vapour pressure hai not wala wo always greater aata hai than that in the solution. Ye to important baat yaha se aapne seekh li. Ab vaise hi yaha par likha hai ki jo solute hai wo non-volatile hai. Non-volatile jaise ki solid form mein jaise hote hai. Jaise urea ho gaya aapke pass, glucose ho gaya aur sucrose ho gaya, ye sare kya hai? Ye non-volatile solutes hai matlab ye aapke vapours nahi denge. To jaise iske molar mass yaad karna bahut jaruri hai, kuch gine-chune aapke substances hote hai jiske aapko molecular mass aapko yaad karne hote hai. Otherwise aapko given hota hai, tension lene ki jarurat nahi hai. Jaise urea ka molar mass hota hai 60, jo glucose hota hai uska molar mass hota hai 180 and jo sucrose sugar hoti hai uska hota hai 342, 342. Theek hai, ye aapko tino to yaad karne hi hai abhi. Ab dekho ab kya ho raha hai? Humne ye dekha ki on addition of non-volatile solute, vapour pressure of solution ya fir solvent decreases. Kya hua jab aapne non-volatile solute dala to vapour pressure kya hua solution mein? Solution ka vapour pressure kam ho gaya. Solution keh lo ya fir solvent keh lo, kyunki jo vapour pressure solution ka hai wo kis, kon contribute kar raha hai? Sirf A factor hai jo hai pressure contribute kar raha hai, B factor jo hai wo contribute nahi kar raha kyunki uski wajah se pressure kya hai? Pressure aapka uski wajah se zero hai.
[9:13]Hum baat karte hai yaha par ye humne sikha ki PA not is greater than PA hai, theek hai? PA not kya hai yaha par? Ki vapour pressure of pure A jab tha component to uska pressure jyada hoga then that of the vapour pressure of A component in solution, theek hai? To ab solute ki baat karte hai, hum solute humne dekha hai, it is the non-volatile jo ki vapours nahi banayega. Jab ye vapours nahi banayega to PB not bhi aap zero likh sakte ho. PB not kya hua ki pressure of B, B kya hai aapka of the solute in pure form, chahe pure form mein lo, chahe solution mein lo, inka kya hoga? Vapour pressure zero hoga kyunki koi vapours hi nahi banenge kisi bhi form mein, isiliye ye dono zero value.
[10:07]Now, ab aate hai hum formula derive karne ki aur. Ab jab yaha par jo non-volatile solute hai isliye isme Raoult's Law nahi lagega. Aapko maine karvaya hai ki jo aapka volatile jo liquid hoga ussi pe aapka Raoult's Law lagega, theek hai? Raoult's Law ke liye at least ek component jo hai aapka, A, one component should be volatile in nature. To component A pe Raoult's Law lagao, according to the Raoult's Law kya hota hai? Agar main A pe lagaau to PA pressure, theek hai? Iska pressure in the solution, wo kis ke equal hota hai? PA not jo constant value hoti hai, A ka pressure in its pure form into the mole fraction of A in the liquid, theek hai? Mole fraction kya hota hai? Ab yaha pe mole fraction kya ho jayega? Mole fraction ho jayega moles ka fraction, moles ka divide karna hai. Agar mole fraction A ka hai number of moles A ke likho divided by total moles, agar A aur B component hai to total moles kya jayega? Unka sum karke aa jayega, okay? Now, ab isme kya karna hai? Iske baad aapne karna hai ek cheez likhni hai, difference in vapour pressure nikalna hai ab aapko, theek hai? Aapko kya nikalna hai? Difference in, theek hai, difference in VP, theek hai, short mein likh rahi hu main, vapour pressure. Ab aisa kyu nikala? Kyunki aapne yaha piche dekha tha ki yaha waha par aapka jo solution mein pressure tha wo kam ho raha tha as compared to its pure form, theek hai? Ab kitna kam ho raha hai wo hum yaha se nikalenge ki difference kitna aaya hai in dono ke vapour pressure mein, theek hai? To usko kya likhenge? Difference in vapour pressure ko hum delta se aapne padha hoga physics mein, delta ya mathematics mein ki change ko delta se dikhate hai. To delta P hua difference in the vapour pressure aur wo difference kis ke equal hoga? Bada minus chhota. Bada kya hai? PA not pure wala. To aap likhoge PA not ki jo value hai wo badi hai minus then that of the PA jo ki aapka solution mein pada hua hai. Now, fir se aap delta P equals to kya likhoge? Ab kya hai according to the jo Raoult's Law aapne PA ki value nikali hai wo aap isme put kar doge. PA not minus of aapka aa jayega PA not kai of A. Okay, ab kya hoga? Yaha se aapka PA not bahar nikal jayega. Yaha par bacha 1 minus kai of A. And aapko sath mein ye relation ek pata hona chahiye ki kai A plus jo bhi jitne bhi component present hai liquid mein unka agar mole fraction ka sum kare to wo equal to one ka aa jata hai, theek hai? Ab 1 minus kai A kitna ho jayega? Kai A ko udhar le jaoge to wo kiski value aa jayegi? Kai B ki aa jayegi. That means jo yaha par aapka 1 minus kai A hai, that means iski value kya aa gayi aapke paas P of A not aur yaha par aa gaya aapka kai B, kyunki iski value aapki kai B aa gayi. Now, yaha par delta P hai and jo PA not hai usko aap dusri side le jaoge. Ab yaha multiplication mein hai, niche kaha jayega? Niche it will go in the denominator aur divide mein chala jayega. And yaha par sirf aur sirf aapke paas kya bacha? Yaha pe bacha aapke paas kai B. Agar main yaha pe delta P ko khol ke agar likhna chahu kyunki delta P kya tha aapke paas PA not minus PA tha. To aapki ye puri value kya aa gayi? PA not, theek hai? Kyunki jo delta hai wo difference hai, PA not minus PA divided by PA not, theek hai? Equals to the kai of B. Theek hai, ye aapke paas first formula aa gaya jisse aapko kya pata chala ki jo relative lowering in vapour pressure hai, wo mole fraction of B ke equal hai. Aur whereas aapko ye pata hona chahiye this, this whole thing, ye puri whole thing kya hai? This whole thing yaha pe main is tarah se bana rahi hu, this whole thing is relative lowering of vapour pressure.
[13:59]Na iske iske bina aise nahi bol sakte ki upar wali cheez R L V P hai, relative lowering of vapour pressure. Nahi, relative ka kya matlab hota hai? With respect to anything. Ab yaha pe divide hai, iska matlab kya ho raha hai? Ki PA not minus jo PA hai matlab jo humne difference dikha vapour pressure ka, wo relative to kis ke dekh rahe hai hum? Pure ke. Ki pure ke with respect to, ki pure component A ke with respect to wo kitna usme change aa raha hai? Relative ka matlab hamesha yahi hota hai ki with respect to something uska hum change dekh rahe hai. To hum kis ke with respect to dekh rahe hai? Hum pure component ke with respect to dekh rahe hai ki jab humne solute dala non-volatile to uska jo vapour pressure hai wo kitna kam hua? Kitna lower hua? Theek hai, isiliye yaha pe likha hai relative lowering of vapour pressure, aur relative lowering of vapour pressure kyu hui thi? Kyunki aapne ek non-volatile solute dala tha. Isiliye ye obvious tha ki jo R L V P relative lowering of vapour pressure hai wo kiski wajah se honi thi? B, that means ye kya hai? Number of, theek hai?
[15:10]Number of, kyunki ye mole fraction, mole's bhi likh sakte ho, mole fraction likh leti hu, mole fraction of non-volatile solute.
[16:47]Non-volatile solute, theek hai? Ki aapke nature pe depend nahi karti hai ki aapke sirf depend karti hai mole fraction mein. Ab ek aur cheez jo NCERT mein aapke paas given hai formulas, theek hai? Ab ye kya hai? This is the mole fraction. Ab mole fraction ko hum fir further kaise karenge? Ki PA not minus jo difference hai aur relative to the PA not hai, theek hai? Tabhi ye relative lowering of vapour pressure kehla hai, wo equal to aapka kya hai? Mole fraction of B hai. Now mole fraction can be written as agar B ka hai to NB upon NA plus NB, theek hai, total aapka itna ho jayega. Ye aapke paas aa gaya, par hum kya karte hai? Ek aur cheez hum karte hai for the dilute, for the dilute solution. Agar dilute solution hum le rahe hai, sometimes aapko formula yahi lagana hota hai numericals mein kyunki jo solution hai wo dilute given hote hai aapke paas. For the dilute solution, dilute solution ka kya matlab hai ki solute jo hai, dilute kab hota hai solution? Jab jo solute jo hai is lesser quantity, theek hai? Is in lesser quantity, agar solute aapka lesser quantity mein hoga tab aap yaha pe kya karte ho? Dilute solution aapko milta hai. Dilute solution agar solute aapka lesser quantity mein hai iska matlab number of moles jo solute ke hai wo very much lesser hoge then that of the NA. So hum kya kar sakte hai? Hum NB ko neglect kar sakte hai. Neglected, theek hai, neglected from denominator. From denominator se hum NB ko neglect kar sakte hai kyunki aapka solution kya hai? Sometimes solution aapka dilute ho jata hai. To NB ko agar neglect karoge to ek naya formula aapke paas mil gaya that is the PA not relative lowering to pura likhoge, relative lowering of vapour pressure. PA not, theek hai, equals to NB upon NA aapka ye formula mil jayega. Ab ye formula hota hai aapka jo most of the aapko numericals mein dekhne ko milta hai ki relative lowering of vapour pressure ka relation with the number of moles. NA, NB kya hai? Number of moles aapke paas hai, theek hai? NA kya ho gaya? Aapka moles of A aur aapke paas NB kya ho gaya? NB is the moles of B component, theek hai? Aapke paas molar mass nahi given hai, solute ka molar mass agar aapko find out karna hai, to aap ye formula directly laga sakte ho aur ise yaad kaise karna hai ki relative lowering of the vapour pressure aur vaise bhi aapko pata hoga not aur A mein confusion ho agar, to aapko hamesha yaad rakhna not wali value hamesha pure ki jyada hoti hai. Isiliye bada minus chhota humne yaha par likha hai. PA not minus PA niche aapka PA hai kyunki relative matlab with respect to, relative to aapne kis se nikalna hai? Bade wali value se dekhna hai ki kitna kam hua. Isiliye niche bade wali value aati hai, theek hai? Aur yaha par agar mass and weight mein aapko formula yaad rakhna hai to aapka kya aa jayega yaha pe WB ya fir W2 matlab weight of the solute, divide kya karoge uska molar mass, theek hai? Agar ab yaha pe mass hai to yaha pe molar mass of dusre ka karoge, A ka molar mass aur niche kya karoge given weight of the A component. Is vajah se aapka aa sakta hai. Ab yaha pe main likh rahi hu so that aap confuse na ho, this is the molar mass, this is the molar mass of solvent. Ek tarah se ye kya hai? Solvent hai kyunki A ko humne solvent liya hai.
[20:31]And molar mass B kya hai aapka? Solute hai to molar mass ye kiska ho jayega? Of the solute and some books mein aapke pass ye kaise one and two ki form mein bhi likha hota hai. Jaise maine yaha bataya ki aap solvent ko one bhi le sakte hai and solute ko two bhi le sakte ho. Is ki jagah A and B ki jagah aap one and two bhi kar sakte ho aur isi tarah aap yaha pe formula bhi dekhoge. To aapke paas yaha par maine teen formulas bata diye, relative lowering of vapour pressure mainly aap yaha se kya cheeze nikal sakte ho? Kis liye ye formula jyada important hai? It tells about the molar mass of the solute. We can find out easily the molar mass of the solute from this formula. So thank you so much, mujhe comment section mein jarur batana ki aapko ye video kaisi lagi, thank you so much.
