To calculate the enthalpy change for the ionization of a 1 mol/L solution of hydrochloric acid HCl at 25 C, we need to consider the following reaction:HCl aq H aq + Cl aq First, let's find the concentration of H ions in the solution using the pH value:pH = -log[H]1.5 = -log[H][H] = 10^-1.5 = 0.0316 mol/LNow, we need to find the degree of ionization of HCl: = [H] / [HCl_initial] = 0.0316 / 1 = 0.0316Since HCl is a strong acid, it ionizes completely in water, and the degree of ionization should be close to 1. However, the given pH value indicates that the degree of ionization is 0.0316, which is not consistent with the behavior of a strong acid like HCl. Therefore, the problem statement seems to be incorrect or contradictory.Assuming that HCl ionizes completely = 1 , we can calculate the enthalpy change using the standard enthalpy of formation for HCl aq , H aq , and Cl aq . The standard enthalpy of formation for HCl aq is -167.2 kJ/mol, while the standard enthalpy of formation for H aq and Cl aq are 0 kJ/mol by definition .H = [H_f H + H_f Cl ] - H_f HCl H = [ 0 + 0 - -167.2 ] kJ/molH = 167.2 kJ/molSo, the enthalpy change for the ionization of a 1 mol/L solution of hydrochloric acid HCl at 25 C would be 167.2 kJ/mol, assuming complete ionization.