Water molecules can undergo a self-ionization reaction to produce very small concentrations of hydronium and hydroxide ions:
H2O + H2O ? H3O+(aq) + OH-(aq)
Use the thermodynamic information below to compute the equilibrium concentration of hydronium ions, [H3O+(aq)], in water at 31 C.
Substance _______change in H kJ/mol________S J/mol K
H2O(l) ____________-285.83__________ 69.91
H3O+(aq)_________-285.83__________ 69.91
OH-(aq)__________ -229.99 _________-10.95