14th May 2012 – Water: Weird or What?

Dr Jichen Li from Manchester will talk to us about the strange properties of one of the most common materials we see around us (particularly in the Manchester area).

Liquid water has importance as a solvent, a solute, a reactant and a biomolecule; structuring proteins, nucleic acids and cells and controlling our consciousness. Life cannot evolve or continue without liquid water, which is why there is so much excitement about finding it on Mars and other planets and moons. Water is the most studied material on Earth but it is remarkable to find that the science behind its behaviour and function is so poorly understood, not only by people in general, but also by scientists working with it everyday.

The small size of its molecule belies the complexity of its actions and its singular capabilities. Liquid water’s unique properties and chameleonic nature seem to fit ideally into the requirements for life as can no other molecule. Although not often perceived as such, water is a very reactive molecule available at a high concentration. This reactivity, however, is greatly moderated at ambient temperatures due to the extensive hydrogen bonding. Water molecules each possess a strongly nucleophilic oxygen atom that enables many of life‘s reactions, as well as ionizing to produce reactive hydrogen and hydroxide ions. Reduction of the hydrogen bonding at high temperatures, or due to electromagnetic fields, results in greater reactivity of the water molecules.

The anomalous properties of water are those where the behaviour of liquid water is quite different from what is found with other liquids. Frozen water (ice) also shows anomalies when compared with other solids.

Although it is an apparently simple molecule (H2O), it has a highly complex and anomalous character due to its intra-molecular hydrogen bonding. As a gas, water is one of lightest known, as a liquid it is much denser than expected and as a solid it is much lighter than expected when compared with its liquid form.

So what can it do for us other than dilute our whiskey?

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