what is the chemical equation for these situations..?

a) there is a straight iron nail in the solidified gelatin solution. the gelatin solution was prepared with phenolphthalein and K3Fe(CN)6.

b) same scenario as with (a) but the nail is bent

c) same with (a) but the nail has copper wire twisted around its middle part

d) same with (c) but the nail has zinc instead of copper

I know the results of each experiments but we were asked what are the chemical equations governing those situations. please help.. thanks a lot..!