March 8, 2010, 1:33 pm
Why can water support life?
Water, water everywhere... and without it there wouldn't be life! So what is it about water that makes it so important?
What was discovered?
The heat capacity of water - how much heat is needed to raise its temperature - is high due to the formation of attractions between water molecules, known as HYDROGEN BONDS.
But the water molecules are moving constantly, so it had never previously been possible to calculate how much energy was associated with a single water molecule and its four other water molecules attracted to it in a tetrahedral arrangement.
By superfreezing water (down to -230 Kelvin) and measuring the tiny changes in the tetrahedral shape of the attractions that each water molecule has to the other four water molecules around it.
This data allowed the calculation of the entropy associated with individual molecules.
Why is it important?
By measuring how temperature and pressure changes affect the order of the water molecules, scientists will be able to understand much better how certain drugs can dissolve more (or less) easily in water, and also how the water can affect the folding of proteins so that they can work properly.
And for life? If our proteins are not folded correctly, they cannot do their job correctly, and that can be... fatal!
What are hydrogen bonds?
When we look at the shape of a water, H2O, molecule, with its two hydrogen atoms and one oxygen atom, we notice immediately that the atoms are not in a straight line.
The electronegative oxygen atom has two lone pairs of electrons which can attract and form hydrogen bonds with hydrogens of other water molecules.
That means that each water molecule can form a total of four hydrogen bonds with neighbouring water molecules. When it does this, it forms a TETRAHEDRAL shape, but the bonds break very quickly and reattach to other water molecules.
The hydrogen bonds of water give it many unusual properties: