A new study, led by the Universities of Bristol and Tokyo, has concluded that a single, simple factor makes water “so anomalous and special,” and in the process may have solved a longstanding mystery. It may come as a surprise to you that there are still aspects about plain, regular water that elude the world’s greatest minds, but to scientists, this colorless substance is something of a headscratcher.
Water isn’t normal for a liquid. We may think it is because of its apparent ubiquity, but it demonstrates a range of properties that are a little unorthodox. Unlike plenty of other liquids, water has a ludicrously high specific heat capacity, which means it takes a remarkable amount of energy to heat up – something that affects our climate, the environment, and life.
It’s physically quite weird in many other ways. It’s most dense when it’s just 4°C (39.2°F); cooling it makes it expand rather than contract. This means that its solid form floats atop its liquid form, and explains why bodies of water freeze from the top down. This isn’t merely odd; this simple fact of physics also determines a large part of how our planet operates.
As the authors of the new paper, published in the Proceedings of the National Academy of Sciences, put it: “Water is the most common and yet least understood material on Earth.”
Imaging techniques and chemical experimentation has come on leaps and bounds in the last couple of hundred years or so, but water’s properties – not all, but some of them – remain enigmatic. In order to unravel at least a handful, a team of mathematicians enlisted the help of supercomputers, and devised new models that could effectively unwrap the individual molecular and atomic interactions within water.
Just a few years ago, it was confirmed by another research group that water obeys a tetrahedral model. Every molecule of water forms a strong hydrogen bond with four adjacent molecules. In fact, the reason that water has such a high specific heat capacity is because it takes a lot of energy to break these hydrogen bonds in the first place.