Timeline for Why don't ions form crystal lattices in water and other polar solvents?
Current License: CC BY-SA 4.0
5 events
| when toggle format | what | by | license | comment | |
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| Nov 9, 2018 at 16:45 | comment | added | porphyrin | (a) re Pauli, yes more energy would be needed, (b) the atoms are always ionised in crystal and solution so no ionisation is needed. (c) yes if dimers are not formed as dielectric is large then dielectric indirectly contributes to entropy | |
| Nov 9, 2018 at 14:00 | comment | added | Sashank Sriram | And from your explanation of entropy, do you mean to say that for NaCl, the entropy change due to spacing out significantly exceeds the (absolute value of) the entropy change due to other factors such as restricting the little freedom of ions in crystal structure, electrostatic forces restricting freedom of ions, etc.? And does the relative permittivity of free space of the polar solvent also contribute to a positive change in entropy as electrostatic forces that constrain freedom are reduced? | |
| Nov 9, 2018 at 13:57 | comment | added | Sashank Sriram | "We expect that ΔH will be positive on dissolution as the crystalline solid exists and it will take energy to make it dissolve." So energy is absorbed to carry out the ionisation. "This will cool the solution if heat is not supplied to keep the temperature constant." Does this mean that the absorbed heat energy will get used up during ionisation? | |
| Nov 9, 2018 at 13:50 | comment | added | Sashank Sriram | "What prevents this is the Coulomb repulsion between electrons (and between nuclei) as any two ions (or atoms) approach one another..." Are you talking about the coloumbic repulsion between two like ions (Cl- - Cl- or Na+ - Na+) as they try approaching the victim ion? "...and the Pauli Exclusion principle" More energy is needed to elevate electrons to the 4s shell in Cl- and 3p shell in Na+: Is that what you're saying? | |
| Nov 8, 2018 at 12:00 | history | answered | porphyrin | CC BY-SA 4.0 |