After this fails (as the clip must be placed gently and flat), obtain a small piece of tissue and place it flat on the surface of a glass of water. To demonstrate the surface tension of water, try floating a paper clip. Hold the biro close to the stream of water and it will be drawn towards the pen. Obtain a biro and rub it vigorously with a woollen scarf or jumper. To demonstrate the electrostatic forces surrounding the water molecule, run a thin flow from the kitchen tap. The diuretic properties of tea and coffee are not very significant in this regard and studies have indicated that most of the water content is retained from these drinks.įor fun, or to amuse and inform children, you might like to demonstrate some of the properties of water alluded to above. About 20 per cent of our water requirement is obtained from solid food while tea, coffee, juice, milk and other beverages are also largely composed of water. However, this does not mean that you must drink two litres of water per day. These figures are approximations and will vary depending on a range of factors including humidity, exercise regime, age and health status. It is this two litres that must be replaced through water intake. The most staggering figure in this regard is the 80,000 litres per day that traverse the capillary walls.ĭaily water loss from the body is accounted for via breathing (800ml), sweating (100ml) and excretion (1.1 litres). The bulk of this water is exchanged within the body, not actually lost. Lymph flow utilises 1 to 2.5 litres per day, while bowel function utilises 8 to 9 litres per day. The kidneys process about 180 litres per day, most of which is returned to the blood stream. It is interesting to consider how much water is processed in the body. This is why some insects can walk on water. Water also has a high surface tension due to lateral attraction between molecules on the water surface. Without hydrogen-bonding, water would boil at about minus 90 degrees centigrade and would exist on Earth as a gas with all that that implies. These allow the individual molecules to bond together quite tightly with their neighbours, accounting for the relatively high boiling and freezing points of water. This results in a structure which behaves rather like a magnet and as a consequence, the hydrogen ends of the molecule are drawn towards the oxygen end to form what are known as hydrogen bonds. The oxygen end of the molecule is electronegative, while the hydrogen ends are electropositive. The molecule of water is not linear, but has an extended V shape, with an angle at the apex of 104.5 degrees. However, what is perhaps less familiar is the phenomenon of hydrogen-bonding which also occurs in water. This formula, H2O, is well known to most people. Water is made up of two atoms of hydrogen combined with one atom of oxygen. Many of the unique properties of water are due to the nature of its molecular structure. During this process carbon dioxide is combined with water, and utilising energy from sunlight, carbohydrates and oxygen are produced. Photosynthesis for example, supplies the primary nutrients for all life forms and is the primary source of atmospheric oxygen. Water is crucial to life, with all known biochemical processes occurring in an aqueous environment. It has unusually high boiling and melting points, is an excellent solvent and most spectacularly, its solid form ice, floats on its liquid form. ![]() Water makes up between 60 and 80 per cent of our body mass and covers more than 75 per cent of the Earth’s surface. Think for example, of standing on a canal bridge during the recent cold snap watching the water flow (liquid), with ice (solid) underfoot while clouds (gaseous) drift overhead. Water is extremely unusual in that it can manifest all three phases at the same time under ambient conditions. Matter generally occurs in three states: solid, liquid and gaseous. Some were beset by both sets of circumstances, writesįollowing recovery from the woes it can bring, it is worth considering this fascinating substance in more detail and the extensive influence it exerts on all our lives. Over the festive period some had none for lengthy periods of time, while others experienced burst pipes, leaks and flooding. Recently however, the primary focus of the populace has been on water. This is hardly surprising given the variety on offer across such a small expanse of land and sea. IRISH PEOPLE are often said to be obsessed by the weather.
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