HIJKLMNO

The title of my post may look odd, but it represents one of the most important chemical compounds on earth. Without it, life would not exist and the search for evidence of the possible existence of life on other planets often comes down to looking for this molecule. It is of course, water.

If you still don’t understand my title, the formula for water is H2O, where the “2” should be subscript representing the fact that there are two Hydrogen atoms in water and one Oxygen atom. This could be misheard as “H to O”, hence my title.

Water could be considered to be an oxide of hydrogen, or hydrogen oxide. There is a closely related compound called hydrogen peroxide (which has two oxygen atoms) which is sometimes used as a bleach and disinfectant. Surely everyone over a certain age has heard of “peroxide blondes“.

Water is sometimes referred to, usually jokingly, as dihydogen monoxide. This silly pseudo-scientific name in sometimes used to create fake polemics against water to trick gullible people, causing them to call for a ban on this noxious and toxic chemical!

We see water all around us, in all three normal states of matter, solid, liquid and gas. Well, ice and water can be nearly transparent, and water in the gaseous state is invisible – we can only see the water vapour that forms when water in the gaseous state condenses into small particles of liquid water suspended in the air.

Water molecules have a slight “V” shape which gives it some amazing properties. it has a minimum density at 4 degrees Centigrade. It freezes at 0 degrees Centigrade so ice is slightly less dense than liquid water and the ice floats. This results in icebergs and the inevitable reference to the Titanic, which as everyone knows hit an iceberg on its maiden voyage, and endless discussions on whether or not both Jack and Rose could have survived the disaster.

Not only does ice keep our drinks cool, but it also forms a skin over ponds and puddles in winter which has the effect of protecting small plants and animals from the worst of winter. This is because the ice acts as an insulating layer and allows some warmth to remain in the waters of the pond.

Most animals can’t survive freezing but some really small ones, like certain frogs and toads and some spiders and insects survive being frozen solid. It is believed that this is because of some constituents of their blood acting as an anti-freeze agent, prevention the destructive formation of ice crystals in the cells and blood of the animal.

Gaseous water is found all around us. It is dissolved, as it were, in air. It’s the water in the air which gives it its humidity. Gaseous water is swept up by the air and boosted to high altitudes by air currents and condenses to clouds, which are masses of water vapour. Ultimately the water falls to earth as rain and runs off into the seas. This whole cycle is driven by heat energy from the sun which causes the evaporation.

On average a human being’s body contains approximately 60% water. It can be higher as in a new-born baby or lower as in obese persons. If a normal person refrains from drinking liquids he or she may become dehydrated, which can result in mental issues and physical ones (which usually go away if the person is rehydrated.

A person loses water by sweating and by urinating. If he or she is in an arid environment, such as a desert, he or she will lose water faster than usual, and if it is not replaced, the dehydration could kill. In hot humid climates, sweating is less effective in controlling the person’s temperature and he or she may die of overheating.

Our planet is (mostly) blue from space mainly because the presence of the water that makes up the seas. However in small quantities and in very shallow depths the colour of water is often due more to the mineral content of the water than anything else. This leads to rivers being called “Blue Nile” (because of the black sediment carried by the river – the word for black is also used for blue in the local dialect) or “White Nile” (because of the light clay sediment carried by the river) for example.

Apart from making up most of our bodies, and being essential for the body’s proper functioning, water has a myriad of uses to humans. It forms a part of many industrial processes for example, and it often provides the power for them, by way of hydroelectric generation. It helps make our crops grow, and we use it and flavour it to provide our beverages.

We also use water for recreation. We swim in the seas and rivers, we sail on them and we dive under them. We hike many kilometres in some cases to view places where water flows over a drop, and we even explore the caves created by the action of water on some rocks.

The deep waters of the seas provide much of our food. Our fishermen haul great numbers of them from the seas with some difficulty and at some expense. There are people who believe that we are doing great damage to the planet by doing this, and that we are causing much marine life to become extinct, which seems to be a big risk to us in the future.

We look for water on other planets, to determine whether or not they will or have supported life. The reasoning behind this is that our way of life, and the way of life of all creatures on Earth depends on water. We cannot conceive of a life form that does not depend on water in some ways. That doesn’t mean, of course, that such life forms do not exist, but just that we can’t currently conceive of a way that such a life form could exist. As Mr Spock might say “It’s life, Jim, but not as we know it”.