ChemistryPushan · Class 9-10
Corrosion: loha, oxygen, paani aur zinc ka bachav
Pul ke saria par rang hota hai, par gaon ki balti par zinc ki chamak (galvanised) kyun hoti hai? Dono jang ko alag tarah se kaise rokte hain?
Socho pehle… phir dekho jawab
Rang sirf deewar ki tarah loha ko hawa-paani se alag karta hai. Galvanising mein zinc ki parat deewar bhi hai, aur zinc loha se zyada reactive hai, isliye parat khurach jaaye tab bhi zinc pehle kharab hota hai aur loha bacha rehta hai.
Corrosion kya hai: koi dhaatu apne aas-paas ki gas ya nami se dheere-dheere kharab hoti hai. Loha ke liye ise rusting kehte hain. Word equation: loha + oxygen + paani → hydrated iron(III) oxide (jang). Oxygen aur paani dono zaroori hain; namak ya acid prakriya ko tez karte hain.
Jang kyun badhti jaati hai: jang bhurbhuri aur jhadne wali hoti hai, isliye woh neeche ke loha ko khula chhod deti hai aur andar tak badhti jaati hai. Aluminium alag hai: uska oxide patla aur chipka hua hota hai, jo andar ke aluminium ko bacha leta hai.
Bachav ke teen tareeke: (a) barrier — rang, tel, grease; (b) galvanising — loha par zinc ki parat; zinc reactivity series mein loha se upar hai, isliye zinc pehle kharch hota hai (sacrificial protection); (c) alloy — stainless steel mein chromium hota hai jo patli, sakht oxide parat banata hai.
Ghar pe try karo
Bade ki madad se ek loha ki keel aur ek stainless steel ka chhota chamcha ek hi katori mein namak ghule paani mein rakho (3-4 din). Roz dekho aur likho: kaun pehle kharab hota hai aur kyun? Dekhne ke baad haath dho lo.
Wow!
Zinc ki ek patli parat khud 'qurbaan' hokar loha bacha leti hai — isi liye ise sacrificial protection kehte hain.
3 sawaal
- Galvanising mein loha par kaun si dhaatu ki parat chadhai jaati hai?
Jawab dekho
Zinc. Galvanising mein loha par zinc ki parat chadhai jaati hai.
- Zinc ki parat khurach jaaye tab bhi loha kyun bacha rehta hai?
Jawab dekho
Kyunki zinc loha se zyada reactive hai aur pehle kharab hota hai. Zinc loha se zyada reactive hai, isliye woh pehle kharch hota hai aur loha bachta hai (sacrificial protection).
- Stainless steel mein loha ke saath kaun si dhaatu milayi jaati hai jo patli oxide parat banati hai?
Jawab dekho
Chromium. Stainless steel mein chromium hota hai jo patli aur sakht oxide parat banata hai.
NCERT se jodo: NCERT Class 10 Science — chemical reactions aur equations (corrosion); metals aur non-metals (reactivity series)