Chemical favorites

These are my reactive chemistry links for December 3rd from 09:39 to 15:19:

  • Kate Middleton’s sapphire ring – Sapphires are just chunks of aluminum oxide. Nothing special really…unless your chemistry professor Martyn Poliakoff who uses the highly pure, transparent and colorless form of the material as a window on his high pressure, supercritical chemistry. In the case of Kate Middleton’s ring, however, the sapphire is full of impurities, mainly iron ions, which give it its deep blue color.
  • Salt lowers the freezing point of water – Dissolving any compound in another will lower its freezing point slightly. So adding salt to water will lower its freezing point. Scattering salt on the roads therefore allows some salt to dissolve in the surface of snow and ice forming on the roads especially as the early cars put pressure on and briefly melt the very surface of any ice as they roll over it. The salt dissolved means that the temperature has to be that bit lower for water to remain frozen or to freeze further. It's only a small effect and if the temperatures are very low, no amount of gritting will help.
  • Arsenic essential for (some) life – A bacterium found in the arsenic-filled waters of a Californian lake is poised to overturn scientists' understanding of the biochemistry of living organisms because it uses arsenic instead of the phosphorus common to other life forms. Hints at a different biochemical past or possibility of exobiology without phosphorus.