8.4: The Eθ(M2+/M) value for copper is positive (+0.34V). What is possibly the reason for this? (Hint: consider its high 

aHθ and low hydHθ)

The Eθ(M2+/M) value of a metal depends on the energy changes involved in the following:
1. Sublimation: The energy required for converting one mole of an atom from the solid state to the gaseous state.
M(s) M(g)   sH(Sublimation energy)
2. Ionization: The energy required to take out electrons from one mole of atoms in the gaseous state.
M(s) M(g)  iH(Ionization energy)
3. Hydration: The energy released when one mole of ions are hydrated.
M2+ M2+(aq)      hydH (Hydration energy)
Now, copper has a high energy of atomization and low hydration energy. Hence, the  Eθ(M2+/M)value for copper is positive.