[AlwaysQuestioning]

Hi guys. I have some questions about the formation of oxides and rusting.

 As for the formation of iron oxides, according to wikipedia,"Oxidation of FeII compounds, e.g. the precipitation of iron(II) salts as hydroxides followed by oxidation by aeration where careful control of the pH determines the oxide produced.[3]", under their page on Iron (ii, iii) oxide.

How does the pH level affect the oxide produced? So is there a chance that Fe2O3 may form instead of Fe3O4 if the surrounding pH level when iron (ii) hydroxide is oxidised can actually affect whether iron (iii) oxide or iron (ii, iii) oxide? Confused here. 


Also, in the page, they mentioned that :"Reduction of Fe2"O3 with CO:[6] gives
3Fe2O3 + CO → 2Fe3O4 + CO2" But shouldn't molten iron form instead (e.g in blast furnace) or is it just a matter of which reactant is added in excess? Just that in the case of blast furnaces carbon is added in excess.?

As for metal oxidation, especially that of transition metals, what determines which oxide is formed?  According to wiki, iron(ii)oxide is thermally unstable under 575 degrees celsius, but what is stopping iron from forming iron (ii,iii) oxide when burnt in air? (Or is it possible?)

Lastly, i've been reading some websites that discuss rusting, and am still confused as to how the pH level affects the rate of rusting.  But i'm stuck between two possibilities when reading these articles. Some mention how acids may actually speed up rusting because of the presence of ions so it technically is an electrolyte and hence provides an electron transport medium for the redox reaction of rust formation. But the acid that is added will also dissolve the hydroxide layer at the same time right? Even dissolving the iron in some cases? Or is it just a matter of the strength/conc of the acid added? (Or should we just stick to normal salt solutions for speeding up rusting? Heh) I remember one of the articles mention how the iron (ii)/(iii) hydroxide layer on the iron actually is rather permeable (you can scrape it off rather easily) to air? So is that a reason why iron rusts/deteriorate much quicker than other metals that have less permeable layers ? (e.g Al2O3? ) So can the iron under the rust layer form rust as well? (However to a lesser degree since it is still somewhat protected?)


Thanks so much. I'm so terribly sorry if i sound stupid, i'm just confused. Again, Thanks very much in advance.

[Hunter2]

Fe₃O₄ is patial oxidied product as FeO*Fe₂O₃. So if the enviroment is alkaline enough iron-II is optained in lower pH also partial oxidised products.
he same of the reduction with carbonoxide. In excess I think iron will be formed.