The enthalpy of neutralization of `HNO_(3)` by `NaOH=-13680 cal//eqt.` When one equivalent of `NaOH` is added to a dilute solution containing one equivalent of `HNO_(3)` and one equivalent of a certain monoprotic weak acid `13960` cals are evolved. Assume that the base is distributed between `HNO_(3)` and the weak acid in the ratio `3:1` and the weak acid is practically nonionized. Calculate the enthalpy of ionization of the weak acid.