In chemical bonding, I am taught an expression that compares the Solvation Energy and the Lattice Energy of an ionic compound which is being dissolved in a polar solvent (could be water, could be something else).
The expression is:
$$\left\lvert r_+ -r_-\right\rvert$$
where $r_+$ denotes radius of cation and $r_-$ denotes radius of anion making up the compound. When this difference is large, solvation energy dominates and when this difference is small, lattice energy dominates. But I don't the reason behind these deductions. Can someone explain?
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mxpici
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If the sum of r+ and r- is about the same, the lattice energy may be about the same for various ratios r+/r-. But if this ratio diverges from 1, the increase of solvation energy of the smaller ion due being smaller is higher than the decrease of solvation energy of the bigger ion due being bigger. But it is my guess, so I do not post it as an answer. It is like 1/3 + 1/3 < 1/2 + 1/4. All implies the same ion charges of compared ion pairs. – Poutnik Dec 21 '20 at 10:41