To calculate the enthalpy of ionization of a hydrogen atom from a hydrogen molecule, we need to consider the following steps:1. Breaking the H-H bond in the hydrogen molecule H2 to form two hydrogen atoms.2. Removing an electron from one of the hydrogen atoms to form a hydrogen ion H+ .Step 1: Bond dissociation enthalpy of H2The bond dissociation enthalpy of H2 is given as 432 kJ/mol. This is the energy required to break the H-H bond and form two hydrogen atoms.H2 2HH1 = 432 kJ/molStep 2: Ionization enthalpy of hydrogen atomThe ionization enthalpy of a hydrogen atom is the energy required to remove an electron from the hydrogen atom to form a hydrogen ion H+ . The electron affinity of H atom is given as -72.8 kJ/mol. The negative sign indicates that energy is released when an electron is added to a hydrogen atom to form a negatively charged ion H- .H H+ + e-H2 = Ionization enthalpy of hydrogen atomSince we know the electron affinity of hydrogen atom, we can use the following relationship to find the ionization enthalpy:Ionization enthalpy H2 = -1 Electron affinityH2 = -1 -72.8 kJ/mol = 72.8 kJ/molNow, we can calculate the overall enthalpy of ionization of hydrogen atom from hydrogen molecule:H_total = H1 + H2H_total = 432 kJ/mol + 72.8 kJ/mol = 504.8 kJ/molTherefore, the enthalpy of ionization of hydrogen atom from hydrogen molecule is 504.8 kJ/mol.