I judged a book by its cover. There was this blue, amorphous blob in the throes of metamorphosis – yet frozen in time. The heading above it read: “The strangest liquid: Why water is so weird”.
It was the Feb 6 2010 edition of New Scientist, which I spied when buying the Jan-Fen 2010 edition of New Zealand Geographic. I had that consumeristic impulse. I bought it. A month later, when I got round to reading the article, I was not disappointed.
The article told the story of Anders Nilsson of Stanford University and Lars Pettersson of Stockholm University in their efforts to explain why water is indeed so weird.
What is common knowledge is that ice floats and water freezes first at the top. This is because water is the densest at 4°C. Very few other liquids behave this way – molten silica seems to be another. But wait, there’s more! Unlike most other liquids water becomes less viscous at higher temperatures, not more. Water has an uncannily high specific heat capacity, which rises both above and below 35°C whereas others have a single trend.
But, the child in us all asks, why?
Well, our heroes of the story, Nilsson and Pettersson, were using X-ray absorption spectroscopy to study the structure of an amino acid, way back 10 years ago. They realised that the water containing the amino acid was more interesting (quelle surprise!), and shifted their gaze to H2O.
Over the course of many more x-rays and several papers, they arrived at a theory to explain all of water’s weirdness: water molecules are capable of stacking themselves in not one but two configurations. One an ordered tetrahedral lattice and one a mixed up hodge-podge. It is the building and breaking of these configurations that ultimately leads, so the heroes say, to water’s wonderful properties.
This being science, though, more research is needed. There are sceptics. There are nay-sayers. There are applications like cheaper desalinisation. And there are children in us all who will continue to ask: But why?