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I am hoping to measure the surface tension between two fluids (salt water and isopropyl alcohol), by measuring the appropriate contact angles, and applying Young's equation: https://en.wikipedia.org/wiki/Wetting#Simplification_to_planar_geometry.2C_Young.27s_relation

As far as I can tell, the surface energy and surface tension are interchangable, however I thought that I should ask people that know better than I do, just to make sure.

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  • $\begingroup$ Nope, both are very different things. $\endgroup$ Sep 9 '20 at 12:55
  • $\begingroup$ So, would the above measurement, together with a capillary measurement suffice to calculate the surface tension? $\endgroup$
    – user109527
    Sep 9 '20 at 12:58
  • $\begingroup$ Surface energy has dimension J/m^2, surface tension has dimension N/m. Their relation is the famous high school formula Work = Force . distance. A liquid with surface tension e.g. $\pu{70 mN/m}$ has surface energy $\pu{70 mJ/m^2}$ $\endgroup$
    – Poutnik
    Sep 9 '20 at 13:10
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    $\begingroup$ Interfacial tension between two liquids implies that they are immiscible. I don't think you will get a distinct interface between isopropanol and an aqueous salt solution. $\endgroup$ Sep 9 '20 at 13:34
  • $\begingroup$ @James Gaidis I generally agree, but I had suspician isopropanol can be salted out, similarly as some other alkohols are. This amateur youtube video seems confirming the idea, resulting in 2 clearly distinguished phases.. $\endgroup$
    – Poutnik
    Sep 9 '20 at 13:55

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