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Given that I have absolutely zero formal (or informal) education in chemistry (sorry about that), I'm struggling to get my head around what appears to be repeated confusions of the term "heat of solution" with regards positive vs. negative. As a specific example, the Wikipedia entry on Erythritol states:

Erythritol has a strong cooling effect (endothermic, or positive heat of solution) when it dissolves in water

However, many other sources, including a number I found via Google Books suggest that Erythritol has a negative heat of solution. For example, this table extract from Food Science, an Ecological Approach:

Erythritol: Noncaloric (0.2 kcal/g), high digestive tolerance, zero glycemic index, does not promote tooth decay, good heat and acid stability, high negative heat of solution.

This is frustrating as I'm trying to find something that has the opposite heat of solution to counteract erythritol's cooling effect, but since many sources seem to contradict each other, I'm struggling to find what I'm looking for.

Which is correct? Or am I using ambiguous terminology?

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The heat of solution (aka enthalpy of the solution and $\Delta\mathrm{H}_{\text{sol}}$) is negative if heat is released. The reason is that energy is leaving the system. The reason you got two different answers is that the sources you referenced are describing two different things. The $\Delta\mathrm{H}_{\text{sol}}$ is positive (endothermic) when dissolved in water, but Erythritol is commonly combined with Inulin which produces an exothermic reaction (cancelling out the cooling effect of the Erythritol).

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  • $\begingroup$ Thanks - I did wonder if it was something like this, because I did stumble across a number of conflicting reports as to the '+/- heat of solution' of erythritol, but none of them seemed to make it abundantly clear if they were talking about the solute or the solvent. $\endgroup$ – indextwo Jan 24 '16 at 11:52

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