Explain with values and reactions from standard reduction potentials tables why neither gold (I) nor gold (III) not to mention the base metal itself, tarnishes (that is can be oxidized by exposure to air)

Answer 1

Look up the oxidation potential for Au and Au^+ and Au^3+
Au ==> Au^+ + e Eo = -1.68

Then look up the reduction potential for oxygen.
O2 + 4H^+ + 4e ==>2H2O Eo = +1.229
If you add the oxidation potential of Au and the reduction potential for oxygen you get a negative number which means the cell is not spontaneous. That explains why Au (the base metal) is not oxidized by air. The same process can be used for Au^+ to Au^3+. The book I used is about 50 years old (what does that tell you?) so you should use your resources to make sure of the numbers. I expect they have changed, at least a little.

Answer 2

Thank you very much. This helps a great deal