is there a way to calculate enthalpy of dissolution of NaOH in small amount of water? I know that enthalpy of dissolution of sodium hydroxide in water is –44,5 kJ/mol. However it assumes the orders of magnitude higher amount of water than NaOH. (Which is not my case.) Is there any formula which does not omit the volume of solvent? (Or a tool which can answer questions such as: "How much heat is released if you make 60% solution of 80% solution?")

Thanks for help.


1 Answer 1


The dissolution enthalpy for concentrated final solutions highly depends on the dissociation and hydration degree, that varies a lot with the substance and concentration.

Therefore particular values for concentrated solutions have to be either measured experimentally, either calculated by some empirical formula, derived from experimental data ( if available ).

  • $\begingroup$ Ahoj :). Thank you for your answer. Unfortunately, I have no experimental data and no calorimeter in my lab. So I will just have to calculate the worst possible scenario. $\endgroup$
    – VDVH
    Commented Mar 12, 2021 at 11:53
  • $\begingroup$ @VDVH Those data should be available $\endgroup$
    – Alchimista
    Commented Mar 13, 2021 at 8:54
  • $\begingroup$ If no data are found, you can derive rough values from experimenting with heating up of concentrated solutions being diluted, and from the limit infinite dilution value. $\endgroup$
    – Poutnik
    Commented Mar 13, 2021 at 9:47

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