question_answer 4)

The value for copper is positive (+0.34 V). What is possible the reason for this?  

Answer:

value for any metal is the sum of enthalpy changes taking place in the steps given below : (is standard enthalpy of atomisation) M(g) + (is standard ionisation enthalpy) M2+(g) + aqM2+(aq) + (is standard hydration enthalpy) Copper has high enthalpy of ionisation (energy absorbed) but low enthalpy of hydration (energy released). Thus is positive.