Water Still Surprises
You might have thought that any chemical controversy about water was settled when Lavoisier definitively established its composition over two centuries ago. You would be wrong, of course, to assume such, even on a molecule as simple as H2O.
Over the years we’ve enjoyed the kerfuffle on the hypothetical polymerized polywater, waited for definitive evidence for liquid water on other planets, and watched with interest the hullabaloo on fluoridation of public water supplies.
Less phantasmagoric but no less important is the structure of water at its interface with air. While this may seem a tad esoteric, when you realize that about 70% of the earth’s surface exhibits this interface, you understand why scientists would be interested in its structure and properties. A recent publication sheds some light by shining light (infrared) on water.
Stiopkin et al. examined the water/air interfacial region using a combination of experiment and theory. The motivation for doing so revolves around understanding the extensive hydrogen bonding network that gives liquid water most of its unique properties, but which can’t fully form at the interface with air. The question is: how deep into the bulk water does this disruptive effect of the surface penetrate? Conventional wisdom was that there were “long range” structural perturbations but the new results show that the effect does not persist past the outermost single layer of water molecules.
This is of interest to all chemists who hoped long range forces might be at play in solution. It’s disappointing, though, to those whose favorite libation is the homeopathic martini—100% gin with only infinitesimal concentrations of vermouth to perturb the fluid structure via long range chemistry.
Tom Tritton is President and CEO of CHF.
Episode 106: Water [Distillations]
Oil and Water [Periodic Tabloid]