Today’s Video of the Day from the American Chemical Society describes the complicated debate over the chemistry of water. Scientists who study water argue that hydrogen bonds alone do not really explain the composition of water on a molecular level.
Unlike most fluids, which become more dense as they get colder and even more dense when they freeze, water is most dense at 4ﾟC. When you get past this threshold, water does not become more dense as it freezes.
In order to support life, the hydrogen bonds in H2O must strike the perfect balance of being strong enough to provide structure and surface tension, but weak enough to provide flexibility. According to ACS, without just the right hydrogen bond conditions, life may have never evolved at all.
Still yet, experts explain that hydrogen bonds do not tell the whole story of water. The molecular interactions within H20 behave in strange and unexpected ways.
Until recently, no method has been sensitive enough to study bonds in H20 molecules. Using a method that relies on an infrared laser to excite these molecules, scientists have now been able to observe the nuclear quantum effect of hydrogen bonds for the first time.
Some experts argue that water is made up of two separate liquids: a high- and low-density liquid. Other scientists point to the shapes that H20 molecules form as they interact, proposing that water molecules form different types of structures. So far, no one has been able to fully explain the unusual behavior of water.
Video Credit: American Chemical Society