How can the ions of the dissolved salt in water affect the thermal capacity and conductivity? What is the mechanism behind that?
Many thanks in advance.
Pure water has a high specific heat, mainly, due to its hydrogen bond[1], a supra-molecular like (statistical mechanics) organization[2]. Dissolving salt (or sugar) in water, effectively modify (H-bond) morphological organization[2] and, reduces :
1. this vital (H-bond) organization, (breakage of H-bonds[2-5] within an extensive 3-dimensional network) or reduces
2. the degrees of freedom[4] and the available number vibrational modes (per unit mass) of the system, or reduces
3. the total number of the (thermal) energy storage modes, e.g. reduces, in physics glossary,
4. the specific heat capacity (Cp).
In short, the dissolution of (most unsaturated) salts in (pure) water, results in the reduction of its Cp.
1. Water molecule is polar, so the partial negative and partial positive ends search for each other in hydrogen bonding. This intermolecular H-bond is manly responsible for its spatial sticky (cohesion, e.g. a supramolecular) organization of the (condensed-phases of the) water and its (well known) amazing properties. Water (liquid): CP = 4185.5 J/(kg⋅K) (15 °C, 101.325 kPa)
2. Water "Structure" and Science : References http://www1.lsbu.ac.uk/water/ref.html ; http://www1.lsbu.ac.uk/water/hydrogen_bonding.html#solacid ; http://www4.ncsu.edu/~franzen/public_html/CH433/lecture/Enthalpy_Deeper_Look.pdf
3. The physics and physical chemistry of water http://www.worldcat.org/title/physics-and-physical-chemistry-of-water/oclc/4478136
4. Vibrational relaxation of pure liquid water http://www.sciencedirect.com/science/article/pii/S0009261406001461#
5. https://www.researchgate.net/post/what_is_the_effect_of_different_hydrogen_bonding_strength_in_liquid_water_on_its_physical_characteristics_density_viscosity_and_surface_tension
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