What is the half-reaction for the reduction of oxygen that occurs with the corrosion of iron? using this reaction, explain why corrosion occurs more slowly in dry climates.

Corrosion is the rusting of iron 
formation requires iron, oxygen, water

4Fe(s) + 3O2(g) + 2H2O(l) --> 4FeO(OH) 

Clearly, without water, there would be no formation of rust. 

Redox half-reactions: 
Fe(s) + 2H2O --> FeO(OH)(s) + 3H+ + 3e- oxidation of iron 
3(Fe(s) + O2 + H+ + 1e- --> FeO(OH)) reduction of oxygen 
 
4Fe(s) + 3O2 + 2H2O --> 2FeO(OH) H+ cancels out, e- cancels out 

Go ask spider man

It should be 2.8 c/m