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I assume that positive surface tension for the interface between two substance implies that the molecules at the boundary are more "comfortable" - their energy is lower when surrounded by similar atoms/molecules ( giving rise to cohesive force ) rather than when they are surrounded by dissimilar atoms/molecules( giving rise to adhesive force ). Is there any solid-liquid pair for which the adhesive force is more stabilizing than the cohesive force?

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  • $\begingroup$ How would this differ from formation of a chemical compound, in which the product is more energetically favorable than the separate constituent elements? $\endgroup$ Commented Oct 29, 2020 at 20:38
  • $\begingroup$ Alcohol and water? $\endgroup$ Commented Oct 29, 2020 at 20:54

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In such a case, the materials will rapidly merge into one homogenous mass. The term you are looking for is "miscible." Any two miscible materials are more stable in a distributed arrangement than they would be in a separated arrangement.

Adrian Howard points out a classic example in the comments: alcohol and water. If the two are combined in the same container, they will mix until evenly distributed, no matter how much of either one you bring to the mix.

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  • $\begingroup$ True, it is quite trivial for a liquid-liquid pair. Does a solid-liquid pair exist? $\endgroup$ Commented Oct 30, 2020 at 7:24
  • $\begingroup$ @NewbieCoder That's an interesting corner case. Liquid Metal Embrittlement comes to mind, like the reaction between solid aluminum and liquid gallium to form an aluminum-gallium alloy. $\endgroup$
    – Cort Ammon
    Commented Oct 30, 2020 at 14:23

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