ChemistryHiranyagarbha · Class 11-12
pH = -log[H+] aur samudra ka buffer
Samudra mein roz carbon dioxide ghulti hai, phir bhi woh acid kyun nahi ban jaata — aur phir bhi 'ocean acidification' kaise ho raha hai?
Socho pehle… phir dekho jawab
Kyunki samudra ka paani thoda basic hai aur carbonate system ek buffer ki tarah kaam karta hai. CO2 ghulne se H+ badhte hain aur pH girta hai — samudra acidic nahi hota, par kam basic ho jaata hai.
Definition: pH = -log10[H+]. Agar [H+] = 10^-3 mol/L toh pH = 3. 25 degree C par Kw = [H+][OH-] = 10^-14, isliye pH + pOH = 14. Strong acid paani mein poora ionise hota hai; weak acid (jaise acetic acid) sirf partly — isliye woh utna tez nahi hota.
Mechanism: CO2 + H2O <-> H2CO3 <-> H+ + HCO3-. Buffer wo ghol hai jo thodi acid ya base milne par pH ko kaafi had tak sthir rakhta hai — samudra ka carbonate system yahi karta hai. Par jab CO2 lagaataar ghulti hai, H+ badhte hain aur pH dheere-dheere girta hai.
Trade-off: buffer ki apni seema hai — woh kaafi asar sambhalta hai, par khatam nahi karta. 'Acidification' ka matlab yeh nahi ki samudra acidic ho gaya; matlab hai ki uska pH neeche ki taraf ja raha hai, aur kai jeevon ko iska farak padta hai.
Ghar pe try karo
Teen numerical khud banao: (1) [H+] = 10^-5 ka pH; (2) pH 9 par [OH-]; (3) pH 3 aur pH 5 mein H+ ka anupaat. Phir ek line likho: buffer aur simple dilution mein kya farak hai?
Wow!
pH ka 'log' hone ka matlab: pH mein sirf 1 ka badlav H+ ions ko 10 guna kar deta hai!
3 sawaal
- [H+] = 10^-4 mol/L ka pH kitna hai?
Jawab dekho
4. pH = -log10(10^-4) = 4.
- 25 degree C par pH + pOH kitna hota hai?
Jawab dekho
14. Kw = 10^-14 hone se pH + pOH = 14.
- 'Ocean acidification' ka sahi matlab kya hai?
Jawab dekho
Samudra ka pH gir raha hai, par woh abhi bhi thoda basic hai. Samudra basic se kam basic ho raha hai — acidic nahi hua.
NCERT se jodo: NCERT Class 11 Chemistry — equilibrium (ionic equilibrium, pH aur buffer)