Supplementary reading Text d. Some facts about water

Ancient Romans used to say: "water is everywhere". However, the ideas on the true proportions of the dis­tribution of water on the Earth and its true role in the life of our planet was found to have been confirmed only by the latest achievements in hydrogeology. The task of hydro-geology as such is to study the problems of formation of groundwater aquifers. It is very important to study the re­sources and reservoirs of groundwaters.

Water has been found to be involved virtually in all geo­logical processes. Without water the mantle material would not be in the molten state. It proves to change the physical properties of the magma rising in volcanos, sharply reduces the melting point of silicate rocks and largely determines the crystallization process.

Water appears to be totally dissociated, its molecules being split into atoms at a depth of 10 kilometers.

Thanks to new methods of research enriched with theo­retical achievements of modern science, primarily in physics and chemistry, virtually all hydrogeological processes have been found to involve water.

The scientists have pointed out that the utilization of water resources should be cardinally reviewed. The discharge of wastewater into lakes and subsurface reservoirs should be reduced and prevented. Now everybody understands the importance of water.

Water is the most common of all liquids and probably the most useful. Naturally occurring forms such as sea water, rain water and lake water are never pure. Consumption increases annually, millions of tons are used each day in industry, so in this respect there is no wonder that there is a water problem.

The answer to heavy demands might well be the sea which covers most of the Earth's surface. Sea water varies in composition, but is, in fact, a vast store house of substances apart from water. In the English Channel there is about 3.5 per cent of solids dissolved in the water, in the Red Sea about 4.1 per cent, while in the Baltic it can be as low as 0.5 per cent. Sodium chloride, common salt, is the most abundant of the solids present. From your knowledge of separation so far, you can easily understand that distillation of sea water would give pure water and leave the solids in the distillation vessel. Of course this has been realised for a long time but the difficulty has been in carrying out this operation economically. To satisfy the heavy demands of industry, a great deal of fuel would be needed to carry out the distillation. However, using the Sun as the source of heat, purification of sea water has successfully been carried out in some countries in recent years.

Text e. So simple and yet so wonderful

Water really is substance No. 1 in life. H₂O! One atom of oxygen plus two atoms of hydrogen. Probably one of the first chemical formulas you ever learn. Now try to imagine what would become of our planet if the water suddenly disappeared from it.

Neither bush nor flower, nor a living thing on the dead Earth. And above it a cloudless sky of a horrifying unusual colour.

So simple a compound, and yet where there is no water, no life, intelligent or unintelligent, is possible.

Why? First of all because water is the most remarkable chemical compound in the world.

Water may be called oxygen hydride. Oxygen is a member of the sixth group, which also includes sulphur, selenium, tellurium, and polonium. The hydrides of all these elements have the same molecular pattern as the water molecule: H₂S, H₂Se, H₂Te, and H₂Po. The boiling points of these compounds are known to gradate regularly from sulphur to its heavier brothers. And unexpectedly we find that the boiling point of water falls out of this series, being much higher than it should be. Water refuses to acknowledge the rules of behav­iour established for the Periodic Table, as it were, and post­pones its transition to the vapour state for 180 degrees. This is only the first amazing anomaly of water.

Its second anomaly has to do with its freezing point. The laws of the Periodic System specify that water shall so­lidify at a temperature of 100 degrees below zero. Water vio­lates this requirement harshly and turns to ice at zero. This wilfulness of water suggests that its liquid and solid states are abnormal on Earth.

According to the rules water should exist here only in the vapour form. Now imagine a world where the properties of water obey the strict regularities of the Periodic System. For fiction writers such a unique picture would be an excel­lent basis for thinking up amusing novels and stories. But for us, and for scientists, it is further evidence that the Peri­odic Table is a much more complex structure than it seems at first glance and that the characters of its inhabitants very greatly resemble those of live people in that they cannot be confined to definite bounds. Water is of a wilful character. But why?

Because the molecules of water have a specific arrangement and for this reason possess a pronounced ability to attract one another. In vain would we look for single molecules in a glass of water. The molecules form groups which scientists call associations. And it would be more correct to write the formula of water as (H₂0)ⁿ, the subscript "n" indicating the number of molecules in the association. These associative bonds between the water molecules are very difficult to break. And that is why water freezes and boils at much higher temper­atures than would be expected.

Notes:

refuses to acknowledge — не бажає рахуватися

water is of a wilful character. — У води свавільний характер

water violates this requirement harshly - вода ці вимоги грубо порушує

it is further evidence - це зайве підтвердження