Acid-Base Heat of Neutralization

[Leclerc]

I know that the heat of neutralization of a strong acid and strong base is -57.7 kJ/gmole. What I need is a good web reference to back this up.

I think the essential equation is

H+ + OH- = H2O + heat of neutralization.

I can find deltaHfo(H2O, liquid, 20 deg.C) =-68.315 kcal/mole, and deltaHfo(OH-, liquid, 20 deg.C) is -54.970 kcal/mole, and, assuming that deltaHfo(H+, liquid) is zero, heat of neutralization should be -68.315-(-54.970) kcal/mole, which works out at -13.4518 kcal/mole, or 56.32 kJ/gmole. This is different from 57.7.

Am I on the right track?

Leclerc.

 

[25362]

Interesting question.

Whether Hess's law of heat summation is always exact isn't known to me. Besides, by arbitrarily giving the standard enthalpy of formation for H⁺_(aq) a value of zero, I think we are probably discarding the energy for bonding hydrogen to surrounding water molecules. Water forms clusters of molecules around the tiny hydrogen ion, and may be this fact explains the anomaly mentioned by you.

If you find a more reasonable answer please report back for my own education.

 

[Homayun]

Have you tried perry?