• # question_answer 25) The energy of an electron in the ground state of the hydrogen atom is$-2.18\times {{10}^{-18}}J$. Calculate the ionisation energy (enthalpy) of atomic hydrogen in J $mo{{l}^{-1}}.$

$IE={{E}_{\infty }}-{{E}_{n}}$ $=0-(-2.18\times {{10}^{-18}})=2.18\times {{10}^{-18}}J$ Ionisation enthalpy per mole $=2.18\times {{10}^{-18}}\times 6.023\times {{10}^{23}}$ $=1.313\times {{10}^{6}}J$