Temperature aur Solubility
Garam paani zyada gholta hai ya thanda? Aaj thermometer haath mein lo! 🌡️
🧭 Is Post Mein
📖 Kahani: Thanda Sharbat, Garam Chai aur Golu ka Jugaad
Garmi ki dopahar thi. Priya ne fridge ke thande paani mein nimbu-sharbat banaya aur khoob saari cheeni daal di. Hilaati rahi, hilaati rahi, par glass ke neeche cheeni ki safed parat jami hi rahi. “Yeh cheeni ghul kyun nahi rahi?”
Usi waqt Golu ki mummy chai bana rahi thin. Golu ne dekha ki ubalti chai mein do-teen chammach cheeni pal bhar mein gayab ho gayi. Golu ne jhat se kaha: “Didi, ek kaam karo. Thoda sa paani garam karke usme cheeni gholo, phir thanda paani milao. Sab ghul jaayega!”
Rohan hans pada: “Garam ho ya thanda, paani toh paani hai. Ghulne ki had thodi badal jaayegi!”
Toh asli sawaal yeh hai: kya taapmaan (temperature) badalne se ghulne ki had bhi badalti hai? Kya har cheez garam paani mein zyada ghulti hai? Aur Golu ka jugaad sahi hai ya Rohan? Chaliye, aaj yahi pata karte hain. 🔍
🎯 Is Post Mein Kya Seekhenge
- Taapmaan badalne se solubility (ghulne ki had) kaise badalti hai
- Garam karne par saturated ghol unsaturated kyun ban jaata hai
- Garam saturated ghol ko thanda karne par crystals kyun bante hain
- Har solid ek jaisa nahi: cheeni ki had bahut badhti hai, namak ki bahut kam
- “Ghulne ki raftaar” aur “ghulne ki had” ka fark
- NCERT ki baking soda wali 20 °C, 50 °C, 70 °C activity, apne shabdon mein
🧱 Basics: Pehle Yeh Aana Chahiye
1. Saturated aur unsaturated: jis ghol mein us taapmaan par aur solute ghul sake, woh unsaturated; jis mein aur na ghule, woh saturated.
2. Solubility: tay matra (jaise 100 g) ke solvent mein, ek taapmaan par, zyada se zyada kitna solute ghulta hai.
3. Taapmaan aur thermometer: taapmaan batata hai ki koi cheez kitni garam ya thandi hai. Ise degree Celsius (°C) mein naapte hain. Barf lagbhag 0 °C par pighalti hai, paani lagbhag 100 °C par ubalta hai, aur kamre ka taapmaan aksar 20–30 °C hota hai. Lab mein ise laboratory thermometer se naapte hain.
💡 Concept: Taapmaan Badla, Had Badli
Step 1: Pichle post ki ek chhupi baat. Humne solubility ki paribhasha mein likha tha “ek taapmaan par“. Yeh shabd bekaar mein nahi likha tha! Iska matlab hai ki taapmaan badlo, toh had bhi badal sakti hai.
Step 2: Zyaadatar solids garam solvent mein zyada ghulte hain. Jaise-jaise paani ka taapmaan badhta hai, zyaadatar thos (solid) solutes ki solubility badhti hai. Cheeni, phitkari (alum), baking soda, sab garam paani mein thande se zyada ghulte hain.
Step 3: Garam karo → saturated ghol unsaturated ban jaata hai. Maan lo kamre ke taapmaan par baking soda ka saturated ghol hai, neeche thoda baking soda bacha hai. Ab ghol ko garam karo aur hilao. Neeche ka baking soda bhi ghul jaata hai! Kyunki naye, zyada taapmaan par had badh gayi, aur ghol ab unsaturated ho gaya.
Step 4: Phir se saturated karo, phir garam karo. Garam ghol mein aur baking soda daalte jao, ek samay aayega jab woh is taapmaan par bhi saturated ho jaayega. Ab aur garam karo, toh had aur badhegi aur bacha hua solute phir ghul jaayega. Yahi NCERT ki activity ka saar hai.
Step 5: Ulti disha: thanda karo → crystals bahar. Garam saturated ghol ko dheere-dheere thanda karo, toh had ghat jaati hai. Ab paani utna solute ghole nahi rakh sakta, isliye extra solute crystals ke roop mein bahar aa jaata hai. Mishri aur phitkari ke crystals isi tarah banaye jaate hain.
Step 6: Sabki had ek jitni nahi badhti. Cheeni ki solubility taapmaan ke saath bahut tezi se badhti hai, lekin namak ki solubility lagbhag utni hi rehti hai. 100 g paani mein:
Namak: 20 °C par lagbhag 36 g → 50 °C par lagbhag 37 g → 100 °C par lagbhag 39 g (bas 3 g ka fark)
Isliye garam paani se namak ka ghol bahut zyada gaadha nahi banta, lekin cheeni ki chashni bahut gaadhi ban jaati hai.
Step 7: Raftaar aur had alag hain. Hilaana aur peesna (powder banana) sirf ghulne ki raftaar badhate hain. Garam karna zyaadatar solids ke liye raftaar aur had dono badhata hai. Isiliye Golu ka jugaad kaam karta hai: thode garam paani mein zyada cheeni ghul jaati hai.
Step 8: Har cheez ka niyam ek nahi. Kuch solids ulte chalte hain. Jaise bujha chuna (calcium hydroxide) garam paani mein thande se kam ghulta hai. Aur gases (jaise oxygen) bhi garam paani mein kam ghulti hain. Gases ki baat hum agle post mein karenge.
Ek line mein: zyaadatar solids ke liye: taapmaan ⬆ = solubility ⬆; taapmaan ⬇ = solubility ⬇ aur extra solute crystals bankar bahar.
🖼️ Diagrams: Picture se Samjho
🔐 Deep Concept: Graph ki Dhalaan (Slope) Kahani Batati Hai
Baat 1: Solubility curve. Scientist taapmaan ko neeche (x-axis) aur solubility ko side (y-axis) par rakh kar graph banate hain. Ise solubility curve kehte hain. Cheeni ki line tezi se upar chadhti hai (dhalaan zyada), namak ki line lagbhag seedhi (flat) rehti hai, aur bujhe chune ki line neeche jaati hai.
Baat 2: Crystals kitne banenge, yeh dhalaan batati hai. Maan lo 100 g paani 50 °C par cheeni se saturated hai (lagbhag 260 g). Ise 20 °C tak thanda karo, toh had lagbhag 204 g reh jaati hai. Toh lagbhag 260 − 204 = 56 g cheeni crystals ban kar bahar aayegi. Namak ke saath yahi karo: 37 − 36 = sirf 1 g. Isiliye namak ko thanda karke crystals nahi banate, balki paani udaa kar banate hain (namak ki kyaariyaan).
Baat 3: Golu ka jugaad poora sahi hai? Thode garam paani mein zyada cheeni gholna sahi hai. Lekin baad mein thanda paani milaane par ghol phir thanda ho jaata hai. Agar cheeni thandi had se zyada ho, toh woh dheere-dheere wapas jam sakti hai. Sharbat ke liye thik hai kyunki saath mein paani bhi badh jaata hai, aur zyada paani zyada cheeni sambhaal leta hai. Dono baatein (taapmaan aur solvent ki matra) milkar had tay karti hain.
✏️ Examples: Taapmaan ka Kamaal
Cheeni ki solubility taapmaan badhne par tezi se badhti hai.
Extra cheeni crystals ban kar bahar aa gayi.
100 g paani mein 20 °C par lagbhag 36 g, 100 °C par lagbhag 39 g.
Naye taapmaan par had badh gayi.
Phitkari ki solubility garmi mein bahut zyada aur thand mein kam hoti hai.
Iski solubility garmi se ghatti hai, toh garam karne par thoda chuna bahar aa jaata hai.
⚖️ Difference Table: Hilaana vs Peesna vs Garam Karna
| Baat | Hilaana / Peesna | Garam karna |
|---|---|---|
| Ghulne ki raftaar | Badhti hai | Badhti hai |
| Ghulne ki had (solubility) | Nahi badalti | Zyaadatar solids ke liye badhti hai |
| Saturated ghol ka neeche bacha solute | Neeche hi rehta hai | Aksar ghul jaata hai (ghol unsaturated ho jaata hai) |
| Ulta karne par (rokna / thanda karna) | Kuch bahar nahi aata | Thanda karne par extra solute crystals ban kar bahar aa sakta hai |
| Example | Chammach se sharbat hilaana | Chai ubaalte waqt cheeni ka turant ghulna |
🚫 Misconceptions: Log aisa sochte hain… lekin
❌ “Garam karne se sirf jaldi ghulta hai, had wahi rehti hai.”
✅ Sach: zyaadatar solids ke liye garmi se raftaar ke saath had bhi badhti hai. Baking soda wali activity yahi dikhati hai.
❌ “Har cheez garam paani mein bahut zyada ghulti hai.”
✅ Sach: namak ki had bahut kam badhti hai, aur bujha chuna aur gases toh garam paani mein kam ghulte hain.
❌ “Saturated ghol hamesha saturated rahega.”
✅ Sach: garam karne par woh unsaturated ho sakta hai, kyunki saturated hamesha ek taapmaan ke liye hota hai.
❌ “Thanda karne par jo crystals bante hain woh koi nayi cheez hai.”
✅ Sach: yeh wahi solute hai jo pehle ghula tha. Cheeni ke crystals cheeni hi hain (mishri bhi cheeni hi hai).
❌ “Saturated ghol sirf bahut garam taapmaan par banta hai.”
✅ Sach: saturated ghol kisi bhi taapmaan par ban sakta hai. Bas har taapmaan par had alag hoti hai.
🔤 Key Terms (Exam mein English shabd hi likhna)
❓ FAQs
1. Kya har solid garam paani mein zyada ghulta hai?
Zyaadatar haan, lekin sab nahi. Cheeni, phitkari, baking soda zyada ghulte hain. Namak bas thoda sa zyada ghulta hai. Bujha chuna (calcium hydroxide) garam paani mein ulta kam ghulta hai.
2. Saturated ghol ko garam karne par kya hota hai?
Zyaadatar solids ke liye had badh jaati hai, isliye ghol unsaturated ban jaata hai aur neeche bacha solute bhi ghul sakta hai.
3. Garam saturated ghol ko thanda karne par kya hota hai?
Had ghat jaati hai, isliye jo extra solute ab ghula nahi reh sakta, woh crystals ke roop mein bahar aa jaata hai. Ise crystallisation kehte hain.
4. Solubility batate waqt taapmaan likhna kyun zaroori hai?
Kyunki ek hi cheez ki solubility alag taapmaan par alag hoti hai. Jaise 100 g paani mein cheeni 20 °C par lagbhag 204 g aur 100 °C par lagbhag 487 g ghulti hai. Bina taapmaan ke number adhoora hai.
5. Kya oxygen jaisi gases bhi garam paani mein zyada ghulti hain?
Nahi, ulta. Gases garam paani mein kam ghulti hain. Iske baare mein agle post “Paani mein Ghuli Gases” mein detail se padhenge.
🧪 Activity (NCERT): Baking soda, teen taapmaan
Yeh demonstration activity hai: teacher ya kisi bade ki nigraani mein hi karein, kyunki isme garam karna padta hai.
Saamaan: beaker, laboratory thermometer, glass rod, lab stand, tripod stand, wire gauze, spirit lamp, paani, baking soda (sodium hydrogen carbonate), chammach.
Kya dikhega: har baar taapmaan badhaane par neeche jama baking soda ghul jaata hai.
Nishkarsh: 70 °C ka paani 50 °C se zyada baking soda gholta hai, aur 20 °C ka paani sabse kam. Yaani baking soda ki solubility taapmaan badhne ke saath badhti hai. Saturated ghol garam karne par unsaturated ban jaata hai.
Yeh activity NCERT ki Class 8 Science book Curiosity (Chapter 9) par aadharit hai, aur yahan apne shabdon mein samjhayi gayi hai.
🏠 Mini Experiments (Ghar pe)
Isse kya pata chala? Gungunaa paani zyada cheeni gholta hai. Taapmaan badha, solubility badhi.
Yahi experiment namak ke saath karo. Dono glass mein ginti lagbhag barabar aayegi! Kyunki namak ki solubility taapmaan ke saath bahut kam badalti hai. Cheeni aur namak ka fark khud dekh lo.
Kisi bade ki madad se ek kap garam paani mein jitni ghul sake utni cheeni gholo. Ghol ko saaf glass mein daalo, usme pencil se ek saaf suti dhaaga latkao, aur glass ko 3–4 din bina hilaye rakh do. Ghol thanda hoga aur paani thoda udega, aur dhaage par chamakdaar cheeni ke crystals ugne lagenge. Yeh ghar ki mishri hai!
🧠 Think Like a Scientist
Sawaal: Rohan kehta hai, “Garam paani mein cheeni sirf jaldi ghulti hai, zyada nahi.” Ek scientist ki tarah ise kaise jaanchoge?
Scientist ka tareeka dekho
1. Observe (dekho): garam chai mein cheeni zyada aur jaldi ghulti lagti hai.
2. Guess (anumaan): agar sirf raftaar badhti hai, toh thande paani ko bahut der tak hilaane par utni hi cheeni ghul jaani chahiye jitni garam mein.
3. Test (jaanch): barabar paani wale do glass lo: ek thanda, ek gungunaa. Dono mein chutki-chutki cheeni daalo aur dono ko utni hi der aur achhe se hilao, jab tak neeche cheeni na bachne lage. Chutkiyon ki ginti likho.
4. Result: gungunaa paani saturated hone se pehle zyada chutki gholta hai, chahe thande ko kitna bhi hilao.
5. Conclusion: garmi se raftaar ke saath had bhi badhti hai. Rohan aadha sahi tha (raftaar badhti hai) par poora nahi. 🔬
🌍 Real Life Mein Taapmaan aur Solubility
- ☕ Chai aur sharbat: chai mein cheeni ubaalte waqt daalte hain, kyunki garam mein zyada aur jaldi ghulti hai. Sharbat ke liye pehle thode garam paani mein cheeni ghol lena ek achha jugaad hai.
- 🍬 Chashni aur mishri: gulab jamun ki chashni garam karke bahut gaadhi banti hai. Mishri banane ke liye gaadhi garam chashni ko dheere thanda karte hain, toh bade crystals ban jaate hain.
- 💎 Phitkari ke crystals: school projects mein phitkari ka garam gaadha ghol thanda karke sundar crystals ugaaye jaate hain.
- 🧂 Namak alag tareeke se: kyunki namak ki had taapmaan se kam badalti hai, samudra ka namak thanda karke nahi, balki paani udaa kar banaya jaata hai.
- 💊 Dawaiyon ki safai: factory mein kai cheezein garam solvent mein ghol kar, phir thanda karke shuddh crystals ke roop mein nikaali jaati hain.
🔁 Recap: Poora Post Ek Nazar Mein
- Solubility hamesha ek taapmaan ke liye hoti hai; taapmaan badlo toh had badal sakti hai.
- Zyaadatar solids: taapmaan ⬆ → solubility ⬆.
- Saturated ghol ko garam karo → had badhti hai → ghol unsaturated ban jaata hai.
- Garam saturated ghol ko thanda karo → had ghatti hai → extra solute crystals ban kar bahar (crystallisation).
- NCERT activity: baking soda 70 °C par sabse zyada, 50 °C par usse kam, 20 °C par sabse kam ghulta hai.
- Cheeni ki had garmi se bahut badhti hai (lagbhag 204 g → 487 g); namak ki bahut kam (lagbhag 36 g → 39 g), 100 g paani mein.
- Hilaana/peesna = sirf raftaar ⬆. Garam karna = raftaar ⬆ aur (zyaadatar) had ⬆.
- Kuch apvaad: bujha chuna aur gases garam paani mein kam ghulte hain.
✍️ Fill in the Blanks
- Zyaadatar solids ki solubility taapmaan badhne par ______ hai.
- Saturated ghol ko garam karne par woh ______ ban jaata hai.
- Garam saturated ghol ko thanda karne par extra solute ______ ban kar bahar aata hai.
- Taapmaan naapne ke liye lab mein ______ istemaal hota hai.
- Hilaane se ghulne ki raftaar badhti hai, lekin ______ nahi badalti.
- Baking soda ka science wala naam ______ hai.
Answers
1) badhti · 2) unsaturated · 3) crystals · 4) laboratory thermometer · 5) solubility (had) · 6) sodium hydrogen carbonate
✅ True / False
- Solubility ka taapmaan se koi lena-dena nahi hai.
- NCERT activity mein 20 °C ka paani 70 °C ke paani se zyada baking soda gholta hai.
- Namak ki solubility taapmaan badhne par bahut tezi se badhti hai.
- Garam saturated cheeni ke ghol ko thanda karne par cheeni ke crystals ban sakte hain.
- Saturated ghol sirf bahut garam taapmaan par hi banta hai.
- Garam karne se zyaadatar solids ki ghulne ki raftaar aur had dono badhti hain.
Answers (kyun ke saath)
1) False: taapmaan badalne se had badalti hai, isliye solubility ke saath taapmaan bataate hain.
2) False: ulta hai. 70 °C ka paani sabse zyada, 20 °C ka sabse kam gholta hai.
3) False: namak ki solubility bahut kam badalti hai (100 g paani mein lagbhag 36 g se 39 g).
4) True: thanda hone par had ghatti hai, extra cheeni crystals ban kar bahar aati hai.
5) False: saturated ghol kisi bhi taapmaan par ban sakta hai; bas had alag hoti hai.
6) True: yahi garmi aur hilaane ka fark hai.
🔘 MCQs
Q1. Zyaadatar solids ke liye taapmaan badhaane par solubility: (a) ghatti hai (b) badhti hai (c) zero ho jaati hai (d) hamesha barabar rehti hai
✅ (b) badhti hai: garam paani zyada solute gholta hai.
(a) yeh sirf kuch apvaadon (jaise bujha chuna) aur gases ke liye hai.
(c) garmi se solute ghulna band nahi hota.
(d) taapmaan se had badalti hai, barabar nahi rehti.
Q2. 20 °C par saturated baking soda ka ghol 50 °C tak garam kiya. Ab ghol hai: (a) Saturated hi (b) Unsaturated (c) Suspension (d) Shuddh paani
✅ (b) Unsaturated: 50 °C par had badh gayi, ab aur baking soda ghul sakta hai.
(a) saturated tab hota jab aur na ghul sake.
(c) ghula hua baking soda uniform ghol banata hai, suspension nahi.
(d) usme baking soda ghula hai, shuddh paani nahi.
Q3. NCERT activity mein kis taapmaan par paani sabse zyada baking soda gholta hai? (a) 20 °C (b) 50 °C (c) 70 °C (d) Teeno par barabar
✅ (c) 70 °C: sabse zyada taapmaan, sabse zyada had.
(a) 20 °C par sabse kam.
(b) 50 °C par 20 °C se zyada, par 70 °C se kam.
(d) activity mein har taapmaan par neeche ka baking soda naye siray se ghula, toh had barabar nahi.
Q4. Kaunsa kaam ghulne ki raftaar badhata hai par solubility nahi badalta? (a) Garam karna (b) Hilaana (c) Thanda karna (d) Koi nahi
✅ (b) Hilaana: sirf jaldi ghulta hai, had wahi.
(a) garam karne se zyaadatar solids ki had bhi badhti hai.
(c) thanda karne se had ghatti hai aur raftaar bhi kam hoti hai.
(d) hilaana sahi jawab hai.
Q5. Garam saturated cheeni ke ghol ko dheere thanda kiya. Kya hoga? (a) Ghol unsaturated ho jaayega (b) Cheeni ke crystals ban sakte hain (c) Cheeni namak ban jaayegi (d) Kuch nahi badlega
✅ (b): had ghatti hai, extra cheeni bahar aati hai.
(a) garam karne par unsaturated hota, thanda karne par nahi.
(c) cheeni ki pehchaan nahi badalti; crystals bhi cheeni ke hi hain.
(d) had badalne se extra solute bahar aata hai, toh badlaav hota hai.
Q6. Kiski solubility taapmaan se sabse kam badalti hai? (a) Cheeni (b) Phitkari (c) Namak (d) Baking soda
✅ (c) Namak: 100 g paani mein lagbhag 36 g (20 °C) se 39 g (100 °C).
(a) cheeni ki had do guna se zyada badhti hai.
(b) phitkari ki had garmi se bahut badhti hai, isliye usse crystals banate hain.
(d) baking soda ki had bhi activity mein saaf badhti dikhi.
Q7. Kaunsi cheez garam paani mein thande se KAM ghulti hai? (a) Cheeni (b) Bujha chuna (calcium hydroxide) (c) Phitkari (d) Baking soda
✅ (b) Bujha chuna: iski solubility garmi se ghatti hai.
(a), (c), (d) teeno ki solubility garmi se badhti hai.
Q8. “Saturated ghol sirf bahut garam taapmaan par banta hai.” Yeh vaakya: (a) Sahi hai (b) Galat hai, saturated ghol kisi bhi taapmaan par ban sakta hai (c) Sirf namak ke liye sahi (d) Sirf cheeni ke liye sahi
✅ (b): har taapmaan ki apni had hoti hai; us had tak ghol bharo toh saturated.
(a) activity mein 20 °C par bhi saturated ghol bana tha.
(c) namak ka saturated ghol kamre ke taapmaan par bhi banta hai.
(d) Golu ki thandi chai/sharbat bhi saturated ho gayi thi.
🔗 Assertion–Reason
Options: (a) A aur R dono sahi, aur R, A ko samjhata hai · (b) A aur R dono sahi, par R, A ko nahi samjhata · (c) A sahi, R galat · (d) A galat, R sahi
1. A: Kamre ke taapmaan par saturated baking soda ka ghol garam karne par neeche ka baking soda ghul jaata hai. R: Baking soda ki solubility taapmaan badhne par badhti hai.
✅ (a): had badhne ki wajah se hi neeche ka baking soda ghulta hai. R, A ka kaaran hai.
2. A: Samudra ke paani se namak thanda karke banaya jaata hai. R: Namak ki solubility taapmaan ke saath bahut kam badalti hai.
✅ (d): A galat hai, namak paani udaa kar banaya jaata hai. R sahi hai, aur isi wajah se thanda karne ka tareeka kaam nahi karta.
3. A: Chai mein cheeni thande sharbat se zyada aasaani se ghulti hai. R: Hilaane se ghulne ki raftaar badhti hai.
✅ (b): dono sahi hain, lekin A ka kaaran taapmaan (garmi) hai, hilaana nahi. Isliye R, A ko nahi samjhata.
📝 Very Short Answer (1 mark)
1. Taapmaan badhne par zyaadatar solids ki solubility par kya asar hota hai?
Solubility badhti hai.
2. Saturated ghol ko unsaturated banane ka garmi wala tareeka batao.
Ghol ko garam karo (zyaadatar solids ke liye).
3. Ghol se solute ke crystals ban kar bahar aane ko kya kehte hain?
Crystallisation.
4. Ek aisi cheez ka naam do jiski solubility garmi se ghatti hai.
Bujha chuna (calcium hydroxide). (Gases bhi garam paani mein kam ghulti hain.)
5. NCERT activity mein baking soda kin teen taapmaanon par ghola gaya?
20 °C, 50 °C aur 70 °C.
📝 Short Answer (2–3 marks)
1. Solubility likhte waqt taapmaan batana kyun zaroori hai? Ek example do.
Kyunki ek hi solute ki had alag taapmaan par alag hoti hai. Example: 100 g paani mein cheeni 20 °C par lagbhag 204 g aur 100 °C par lagbhag 487 g ghulti hai. Bina taapmaan ke solubility ka number adhoora hai.
2. Hilaane aur garam karne ke asar mein kya fark hai?
Hilaane se sirf ghulne ki raftaar badhti hai, had nahi. Garam karne se zyaadatar solids ke liye raftaar aur had dono badhti hain. Isliye saturated ghol hilaane se unsaturated nahi hota, lekin garam karne se ho jaata hai.
3. Mishri ya phitkari ke crystals kaise banaye jaate hain? Science samjhao.
Garam paani mein had tak solute gholkar gaadha saturated ghol banate hain. Phir use dheere-dheere thanda hone dete hain. Thanda hone par had ghatti hai, toh extra solute ghula nahi reh paata aur crystals ban kar bahar aa jaata hai.
4. Priya ka thanda sharbat: neeche cheeni jami hai. Do tareeke batao jinse yeh ghul jaaye, aur har ek ka kaaran.
(1) Sharbat ko thoda garam karo: taapmaan badhne se cheeni ki had badhti hai. (2) Aur paani milao: solvent badhne se had badhti hai. (Sirf hilaana kaam nahi karega, kyunki woh had nahi badhata.)
📝 Long Answer (5 marks)
1. NCERT ki baking soda wali activity ka varnan karo: saamaan, steps, observation aur nishkarsh. Safety ki do baatein bhi likho.
Saamaan: beaker, lab thermometer, glass rod, lab stand, tripod, wire gauze, spirit lamp, paani, baking soda.
Steps: lagbhag 50 mL paani 20 °C par lo; baking soda daalte-hilaate jao jab tak kuch neeche na bache. Garam karke 50 °C tak le jao aur hilao. Phir 50 °C par aur baking soda daalo jab tak kuch neeche na bache. Phir 70 °C tak garam karo aur hilao.
Observation: 50 °C aur phir 70 °C par neeche jama baking soda ghul jaata hai.
Nishkarsh: baking soda ki solubility taapmaan ke saath badhti hai: 70 °C > 50 °C > 20 °C. Garam karne par saturated ghol unsaturated ho jaata hai.
Safety: (1) spirit lamp aur garam beaker teacher ki nigraani mein; (2) garam beaker nange haath se na pakdein, lamp topi se bujhaayein.
2. “Taapmaan badalne se solubility badalti hai” ko cheeni, namak aur bujhe chune ke examples se samjhao. Crystallisation bhi samjhao.
Cheeni: 100 g paani mein lagbhag 204 g (20 °C) se 487 g (100 °C): had bahut tezi se badhti hai.
Namak: lagbhag 36 g se 39 g: had bahut kam badhti hai.
Bujha chuna: iski had garmi se ghatti hai, yaani ulta niyam.
Nishkarsh: zyaadatar solids garam paani mein zyada ghulte hain, par har solute ka badlaav alag hota hai aur kuch apvaad bhi hain.
Crystallisation: garam saturated ghol ko thanda karne par had ghatti hai, aur extra solute crystals ban kar bahar aata hai, jaise mishri aur phitkari ke crystals. Namak ki had kam badalti hai, isliye use paani udaa kar nikaalte hain.
📰 Case-Based Question
Diwali se pehle Meera ki dadi gulab jamun ke liye chashni bana rahi thin. Unhone kadhai mein ek glass paani aur teen glass cheeni daali aur garam kiya. Thodi der mein saari cheeni ghul gayi aur gaadhi, saaf chashni ban gayi. Raat ko bachi hui chashni ek katori mein rakh di gayi. Subah Meera ne dekha ki katori ke kinaron aur tale par cheeni ke chamakdaar daane jam gaye the. Dadi muskura kar boli: “Yahi toh ghar ki mishri hai!”
Q1. Teen glass cheeni ek glass paani mein kaise ghul paayi?
Garam karne se paani ka taapmaan badha aur cheeni ki solubility bahut badh gayi. Isliye garam paani itni zyada cheeni ghol paaya.
Q2. Raat bhar mein chashni ke saath kya hua jisse daane jame?
Chashni thandi ho gayi, toh cheeni ki had ghat gayi. Jo extra cheeni ghuli nahi reh sakti thi, woh crystals ban kar bahar aa gayi (crystallisation). Saath mein thoda paani bhi uda hoga.
Q3. Subah wali chashni (daanon ke upar ka ghol) saturated hai ya unsaturated? Kyun?
Saturated. Kyunki uske neeche bina ghuli cheeni (crystals) maujood hai; us taapmaan par woh aur cheeni nahi ghol pa rahi.
Q4. Daanon ko wapas ghulane ka ek tareeka batao.
Chashni ko phir se garam karo (ya thoda paani milao). Garmi se had badhegi aur daane ghul jaayenge.
🚀 HOTS
1. Namak aur cheeni dono ke garam saturated ghol ko 100 °C se 20 °C tak thanda kiya (100 g paani har ek mein). Kis ghol mein zyada crystals banenge aur lagbhag kitne?
Cheeni mein. Cheeni: lagbhag 487 − 204 = 283 g crystals. Namak: lagbhag 39 − 36 = 3 g. Cheeni ki had taapmaan ke saath bahut zyada badalti hai.
2. Ek ghol ko garam karne par usme se thos kan bahar aane lage. Is solute ke baare mein kya keh sakte hain?
Iski solubility taapmaan badhne par ghatti hai (jaise bujha chuna). Garam karne par had kam hui, isliye extra solute bahar aa gaya.
3. Golu kehta hai, “Garmi se sirf jaldi ghulta hai.” Usko galat saabit karne ke liye ek experiment design karo.
Barabar paani ke do glass lo: ek thanda, ek gungunaa. Dono mein ek hi cheez (cheeni) chutki-chutki daalo aur dono ko barabar der tak achhe se hilao, jab tak neeche cheeni na bache. Ginti likho. Gungunaa paani zyada chutki gholega, chahe thande ko kitna bhi hilao. Iska matlab garmi se had bhi badhti hai, sirf raftaar nahi.
🏆 Olympiad Corner
Neeche diye “Solute X” ki solubility (100 g paani mein): 20 °C par 30 g · 40 °C par 45 g · 60 °C par 60 g.
1. 60 °C par 50 g paani mein zyada se zyada kitna X ghulega? (a) 60 g (b) 30 g (c) 15 g (d) 120 g
✅ (b) 30 g: aadha paani, aadhi had: 60 ÷ 2 = 30 g. (a) yeh 100 g paani ki had hai. (c) yeh 20 °C par 50 g paani ki had hogi. (d) yeh 200 g paani ki had hogi.
2. 100 g paani mein 60 °C par saturated X ka ghol 20 °C tak thanda kiya. Kitna X crystals ban kar bahar aayega? (a) 60 g (b) 15 g (c) 30 g (d) 0 g
✅ (c) 30 g: 60 − 30 = 30 g. (a) saara X bahar nahi aata, 30 g ghula rehta hai. (b) yeh 60 °C se 40 °C tak thanda karne par hoga (60 − 45). (d) had ghati hai, toh kuch na kuch bahar aayega.
3. 40 °C par 200 g paani ko X se saturated karne ke liye kitna X chahiye? (a) 45 g (b) 60 g (c) 90 g (d) 120 g
✅ (c) 90 g: har 100 g pe 45 g, toh 200 g pe 45 × 2 = 90 g. (a) sirf 100 g paani ka. (b) 60 °C par 100 g ka. (d) 60 °C par 200 g ka.
📚 Aur Padho (External Reference)
- NCERT Class 8 Science Curiosity, Chapter 9 (official PDF)
- DIKSHA: Sarkar ka free learning platform, NCERT ke videos ke liye
💖 CharuMam Motivation
Thanda paani thodi si cheeni ke baad “bas” bol deta hai. Lekin wahi paani thoda garam ho jaaye, toh kai guna zyada cheeni apne andar sama leta hai.
Beta, aap bhi aise hi ho. Jab mann thanda aur udaas hota hai, toh ek sawaal bhi bhaari lagta hai. Lekin jab aap mein utsaah ki garmi hoti hai, aap kai guna zyada seekh lete ho. Toh padhai se pehle thoda khud ko “garam” karo: ek gilaas paani, do minute stretch, aur ek muskaan. Aur haan, jo seekha hai woh crystals ki tarah dheere-dheere, aaraam se jamta hai. Jaldi mat karo, roz thoda karo. 🌱
— CharuMam
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