Hydrogen Hydroxide or Hydroxic Acid?

"You know when you go to a concert and it's like punk rock and the kids get on stage...and they jump into the crowd, stage diving? People think that's dangerous - but not me. Because humans are made out of 95% water, so the audience is 5% away from a pool."

The esteemed, late Hedberg may be a few percentage points off (adult humans are closer to 60% water), this is just one reason why water is one of the most consistently awesome chemicals that exists.

Structure of Water

One of the first chemical formulas many people learn, H₂O is a common name for water. A more fitting chemical formula is HOH. H in this case is an ion of hydrogen, often called hydron, and is a positively charged ion (also called a cation). OH, also called hydroxide, is a negatively charged ion (also called an anion). Unfortunately there are no dogions (I can't guarantee there won't be other bad chemistry jokes later).

This combination of a cation and an anion results in a polarized molecule (the oxygen ends up negatively charged, the hydrogen ends become positively charged). This relatively unique structure is one of the primary reasons for all of water's awesomeness.

So, what is cool about water?

Properties of Water

Water is amphoteric, which means it is both an acid and a base (hence the title of this post). Contrary to what the Simpsons would like you to believe, mixing acids and bases doesn't cause massive explosions that turn you green (unless they're very concentrated...but they still won't turn you green). You'll get a salt and water. The most common chemical formula you'll see for illustrating this concept is the reaction between hydrochloric acid (HCl) and lye (sodium hydroxide - a base, NaOH) to get table salt (sodium chloride - NaCl) and H₂O. I was never good with chemical formulas written out in prose, so here's what it looks like:

NaOH + HCl → NaCl + H₂O

Water can be superheated above its normal boiling point. If distilled water is cooked in a container without deformities or dirt (no scratches and no dust) it can surpass its normal boiling point. It also tends to instantaneously boil when an impurity is added to the water (a spoon, sugar, etc.). This is where the idea of 'explosive water' comes from...although it's not so much exploding as it is simultaneously boiling everywhere.

Water has a high heat of fusion (energy needed to freeze) and high heat of vaporization (energy needed to turn into a gas). This gives it great thermoregulatory properties. This is the reason for warmer temperatures near lakes during winter (the water gives heat to the surrounding air in order to freeze), and why sweat cools the body (the water takes heat from your body in order to evaporate). Any liquid could perform this action, but water does it particularly well due to the large amounts of energy needed to overcome the attraction between individual molecules. This is also why water is a preferred coolant in many engines and industries (it takes a lot of heat to boil water). IUPAC standards require that this paragraph maintain an excitment level of 6.0 ±0.5 exciteograms. How about a picture of Schwarzenegger as Mister Freeze to meet this quota?

Ice floats in water. As it cools from 4°C to 0°C, water expands. When water freezes normally it forms a crystal lattice which has more volume than its watery counterpart (same mass in a larger space). This is why ice cubes (...and icebergs - take that Titanic) float. Another side effect from freezing is that icebergs end up mostly freshwater. Although saltwater has a lower freezing point than freshwater, the formation of ice crystals slowly presses out salt and other impurities in the water.

Water has the highest surface tension of all non-metallic liquids (not including solutions with water as the solvent like saltwater or sugar water). Surface tension is an aspect of all liquids, but the polarity of water increases its surface elasticity. Surface tension is the result of intermolecular forces trying to pull the liquid into the smallest possible volume (if gravity didn't exist this would be a sphere). Since the liquid is as compact as it's going to get (liquids aren't easily compressible), this means things need a certain amount of force to penetrate into the liquid. This is also why water forms spherical droplets when falling and people urinating on electric fences aren't electrocuted.

Pure water doesn't conduct electricity. Unfortunately this property isn't as useful for swimmers as it might seem. If exposed to the atmosphere the water will disolve some of the air (and won't be pure anymore). Thus we have electrocuted swimmers. 

Electrolysis separates water into its consitutent parts - diatomic hydrogen and diatomic oxygen. Running an electric current through water seperates the water into the natural state of its two component elements (hydrogen gas and oxygen gas). Unfortunately this isn't a good way to make hydrogen as a fuel since it takes more electrical energy to create the hydrogen than you'd get from burning it.

Water, like its constituent parts, is transparent, odorless and tasteless. All the crappy tasting water you've ever drank is due to impurities (I don't mind iron so much). It does take on a slight bluish tinge in large quanitites, and this is a minor reason why the sky is blue.

Without even touching hydrology or the biologic processes that rely on water, I believe we have defintively established that water is awesome. Way better than isopropanol and tetrafluoroethylene anyway.