Qualification > Sciences
IGCSE CHEMISTRY DOUBTS
NidZ- Hero:
--- Quote from: ~VIN1094~ on June 06, 2010, 09:01:47 pm ---https://studentforums.biz/index.php/topic,1411.msg255912.html#msg255912
^^check this
--- End quote ---
thanz n hw wuld do u draw structure of diamond
Vin:
--- Quote from: Lariemeeva on June 06, 2010, 09:12:28 pm ---Can anyone explain in terms of ions and electrons why steel does not rust when covered with zinc. I think I have some misconceptions on this part.
Thanks in advance.
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OK,zinc is welded over iron (in case of a ship). It is more reactive so it gives up e- to form +ve ions more readily. So the zinc dissolves..
2Zn ----> 2Zn2+ + 4e- (oxidation)
The electrons flow to the iron, which passes them on..
O2 + 2H2O + 4e- ---> 4OH-
Adding the incomplete reactions
2Zn + O2 + H2O ----> 2Zn(OH)2
Vin:
--- Quote from: Nidzzz on June 06, 2010, 09:17:53 pm ---thanz n hw wuld do u draw structure of diamond
--- End quote ---
TheLonelyIsland:
Zinc forms positive ions more easily than iron (more reactive), basically it gets oxidized faster in a reaction with oxygen from air to form zinc oxide. When oxidized, it loses electrons (always) to the metal it protects, so iron in this case has a constant supply of electrons, therefore isn`t in a danger of losing them. The same is with cathodic protection in which electricity connected to the metal supplies it with electrons... Basically preventing the metal to form positive ions, aka, give electrons away... I hope this explanation is sufficient ;)
Lariemeeva:
Thanks VIN and TLI~
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