Question

The first ionisationpotential of Na is 5.1 eV . The value of electron gain enthalpy of Na⁺will be?

Answer 1

Ionization potential is the energy involved in the reaction, Na =Na⁺ + e^-

Electron gain enthalpy of Na⁺ is the reaction Na⁺ + e^- = Na
This is reverse of the first reaction and hence the enthalpy of the reaction is -5.1eV