$\ce{LiCl}$ has an enthalpy of solution of $\pu{-37.1 kJ/mol}$, so its dissolution process is exothermic. Does this mean that it's crystallization process is exothermic? I'm asking since I've looked up "exothermic crystallization" and "the crystallization of endothermic solutions" and couldn't find anything.

So my question is: Is crystallization always an exothermic process, or is it endothermic for substances such as this whose enthalpy of solutions are negative?

  • $\begingroup$ There is also a heat of dilution that you need to account for. $\endgroup$ – Zhe Oct 29 '17 at 14:58
  • $\begingroup$ Oh okay. Unfortunately I'm not really familiar with what that is, but what effect does it have on the energy released or absorbed by the crystallization? $\endgroup$ – Dahen Oct 29 '17 at 15:02
  • $\begingroup$ You don't just form the crystals from a 1 molar solution, so you'll need to account for the fact that you're presumably doing so from a more concentrated solution. Since enthalpy is a state function, you can just sum the enthalpy changes from the two processes to determine the total enthalpy change. $\endgroup$ – Zhe Oct 29 '17 at 15:05
  • $\begingroup$ I see. So can a sum of those two enthalpies ever result in a value that makes crystallization endothermic? $\endgroup$ – Dahen Oct 29 '17 at 15:08
  • $\begingroup$ Depends on the substance, but it could be. $\endgroup$ – Zhe Oct 29 '17 at 23:49

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