The first ionisation potential of Na is 5.1 eV.The value of electron gained enthalpy of Na+ will be
Hello Aspirant!
Ionisatiom potential is the energy required to remove electrons from 1 mol of a substance. Whereas, electron gain enthalpy is the energy released when electrons are added to 1 mol of a substance. So both the values are same in magnitude but different in sign. Therefore the electron gain enthalpy of Na+ will be (-5.1)eV.
Hope this helps!