Written by William Fryer - MA Oxon
There has been much excitement at the recent discovery of water on Mars. Finding water was one of NASA’s Martian probe Curiosity’s chief tasks. Water is considered by scientists to be the crucial building block of life – if there’s water on Mars, there may once have been Martians.
We all need water to stay alive. Here are some facts about the most important substance on our planet.
1 – If we know one chemical formula, it’s likely to be that for water, H20. The H stands for hydrogen and the O for oxygen, two gases, which when combined at a ratio of two hydrogen atoms to one oxygen atom give us water.
2 – We generally think of water as a liquid, but it can also exist as a gas and a solid. Solid water is of course, ice, and the steam that comes out of our kettles is water as a gas, steam.
3 – Water defines our temperature scales. It boils at 100 centigrade and freezes at zero centigrade. The Fahrenheit scale was also designed around water. Its zero was the freezing point of salt water and there were 180 degrees between pure water’s freezing and boiling points.
4 – We can control these though. Add impurities to water and its boiling point will rise and freezing point lower, that’s how antifreeze in our car engines works.
5 – Atmospheric pressure also changes the properties of water. The higher in the atmosphere you go – reducing the pressure – the lower the boiling point of water. At the top of Mount Everest, the boiling point of water is 68 centigrade; in the deepest oceans, water stays liquid well beyond its notional 100 degrees boiling point.
6 – Our planet is a watery world. Around 70% of the surface of the Earth is water, most of it – around 70% - in salty oceans that we cannot drink. The total amount of water on the planet is somewhere in the region of 326 million cubic miles.
7 – Seawater contains 35 grams of salt in each kilo of water on average.
8 – Water is the best solvent on the planet; scientists call it the universal solvent, because so many solids can be dissolved in it.
9 – All the water on earth is millions of years old. The planet is a closed system, nothing new arrives and very little leaves our atmosphere.
10 – Water cycles endlessly through this system. Evaporating into the atmosphere where it forms clouds and, when the conditions are right, rain or snow.
11 – Pure water is tasteless and odourless. It’s very rare to encounter pure water; the stuff that comes out of our taps is harmless but not pure, unless you distil it.
12 – Water is neither acidic nor alkaline. The pH scale of acidity is another that is based around water, which has a neutral pH of seven.
13 – We too are mostly water. Adults are around 70% water and a new born around 80%. Our cells are mostly water; things like DNA are dissolved in water.
14 – There is much debate about how much water we should drink, but drinking more than three gallons-a-day is likely to make you very ill. Around eight cups or 2 litres is the most common recommended daily intake. There are water distillers on the market to purify water if you are worried about its quality.
15 – This overdosing on water causes what is called ‘water intoxication’ when the level of fluid dilutes sodium in the blood and floods the brain.
16 – Most of the things we drink, from tea to soft drinks, still contain large amounts of water. The same is true of our food.
17 – Most of the world’s fresh water is underground.
18 – The United States of America consumes 346,000 million gallons of water a day, 80% of it in agricultural and energy generation uses.
19 – The vast majority of water we each use each day is flushed away down the drains.
20 – Thirst – our body’s signal to take on water - only hits us after we’ve lost more than 1% of the water in our body.
21 – Losing weight very quickly through exercise is often the result of shedding water rather than fat. That takes rather longer.