When I galvanize iron or attract a more reactive block of metal to iron, that metal will oxidise instead of the iron. I understand that anions need to be present for the reaction to occur as the more reactive metal will have transferred its electrons to iron. So the eg magnesium will oxidise to Mg2+ and react with any anions present. However, when I galvanize an iron bin in the air, and it receives a crack so the iron is exposed too, the iron will not rust. So the zinc layer will transfer electrons to the iron bin, but how can the zinc exist as Zn2+? Since there are no anions in the air? I read a little on galvanising corrosion and it said that if moisture is present then the more reactive metal will corrode, but I thought that this is only true if the moisture has some anions already like in the soil. But in air even if there is moisture there is no anions so how can it rest with the Zn2+ ions? Thanks so much for the help.