Notes on the Text

1 In contrast to — в противоположность 2. Any given sample — любой имеющийся образец 3 one and a half times — в полтора раза

4. Index of refraction — коэффициент преломления

5. 10 Times larger — в 10 раз больше

TEXT. SUPERDENSE WATER

There is a tradition among physical chemists to regard the properties of liquids as essentially invariant. When comparing them with gases we can see that they are only slightly com­pressible.

In contrast to crystalline solids liquids do пот. exhibit variability. These and some other characteristic properties of liquids were the reason that the commonest of them viz. water was adopted as the basis for the definition of several in­ternational standards of measurement.

The choice of a cubic centimetre of water as the internation­al unit of mass has been motivated by the fact that any given sample of water has a maximum density at a special tempera­ture, near which small changes in the temperature cause very small changes in the density, and hence negligible changes in the mass of standard volume.

Having carried out a number of investigations the scien­tists made a very interesting discovery, i.e. a new stable form of water having the density almost one and a half times that of ordinary water was obtained. This water was named Water II. Having examined its properties they found out that its index of refraction was equal to about 1.48 to 1.49. But when Water II was diluted with ordinary water (Water I) this value dropped to the value for pure water, i.e. 1.33. Having contin­ued their work the scientists stated that the density of Water II was equal to that of pure water. Then it was very important to learn the stability of the molecules of Water II and the forces responsible for their stability.

It was assumed that under the impact of the electrons on the molecules of Water II, these molecules are immediately broken down into ordinary molecules of H_aO. And that Wat­er II in solution has a definite molecular weight that is approximately 10 times larger than that of ordinary water.

Many scientists working in this field got interested in it. Thus the Soviet scientist O. F. Vasiliev has expressed the hypothesis that noctilucent clouds consist of drops of Wat­er II which in contrast to drops of ordinary water may remain at a height of 90 kilometres without being evaporated.

Some scientists suggested the possibility that on Venus wat­er exists mainly in the form of Water 11. This question attract­ed the attention of many scientists and will be discussed in future.

II

Water is hydrogen oxide, a compound of hydrogen and oxy­gen. It can be made if hydrogen or a hydrogen-containing substance are burnt in air or oxygen.

Most of the world’s water is liquid, but an important frac­tion is solid as ice and snow.

Many mineral substances contain water of crystallization (e.g. copper sulphate) and in the atmosphere there are millions of tons of water vapour. Clouds consist of minute droplets of water or crystals of ice.

Water dissolves a very large number of substances and is the most important solvent. It does not dissolve greasy, fatty substances or most plastics.

Having found the composition of water, the scientists could investigate its properties. It was stated that ordinary water is impure, it usually contains dissolved salts and dis­solved gases, and sometimes organic matter.

For chemical work water is to be purified by distillation. Pure water is colourless, tasteless and odourless. Rain water formed by the condensation of water in the air is nearly pure water, containing only small proportions of the dust and of dissolved gases.

Having examined the properties of water, the chemists found that physical properties of water can be used to define many physical constants and units.

The freezing point of water (saturated with air at 1 atm pressure) is taken as 0°C and the boiling point of water at 1 atm is taken as 100°C.

The unit of volume in the metric system is chosen so that 1 ml of water at 3.98^CC (the temperature of its maximum density) weighs 1.000 g/cm³.

So water is one of the most important of all chemical sub­stances. It is a major constituent of living matter and of the environment in which we live.

Remember the following words and word combinations:

superdense hence height

to regard negligible mainly

invariant	stable	to attract
to compare	that	future
slightly	to dilute	to bum
in contrast	to drop	fraction
to exhibit	to state	purify
variability	to assume	freezing point
common	impact	to saturate
viz. (namely)	immediately	to choose
to adopt	ordinary	major
choice to cause	approximately to remain	environment

Ex. 13. Answer the following questions:

1. How do physical chemists regard the properties of liq­uids? 2. What is the difference between liquids and gases?

3. What is the difference between liquids and crystalline sol­ids? 4. Why was water adopted as the basis for the definition of several international standards of measurement? 5. What is the choice of a cubic centimetre of water as the international unit of mass motivated by? 6. What is the index of refrac­tion of water equal to? 7. When are the molecules of Water II broken down into ordinary molecules of H₂0? 8. What hy­pothesis has the Soviet scientist O. F. Vasiliev expressed? 9. What is water? 10. What substances can’t be dissolved in wat­er? 11. What properties of water do you know?

Ex. 14. Find the pairs of synonyms and remember them:

at once, learn, stable, mainly, several, chiefly, find out, almost, immediately, get, nearly, obtain, invariable, some.

Ex. 15. Find the pairs of antonyms and remember them:

impossible, stable, purity, solidify, unstable, indefinite, liquefy, impurity, definite, possible.

Ex. 16. Find the adjectives in the following list of words:

almost, equal, choice, density, stable, tasteless, approxi­mately, appropriate, near, liquid, colourless, high, highly.

Ex. 17. Find the verbs In the following list of words:

exhibit, purity, purify, choice, choose, learn, measure, equal, differ, different.

Ex. 18. Translate the following words into Russian:

near—nearly equal—equally

high—highly hard —hardly

dense—densely

Ex. 19. Translate the following sentences paying attention to the words in bold type:

1. Rain water is nearly pure water. 2. Sea water contains nearly 3.6 per cent of mineral matter in solution. 3. Hydrogen ions can be in solutions of acids and are responsible for their characteristic properties. 4. Pure substances may be of one or two kinds viz. (namely) elements and compounds. 5. If we weigh the hydrogen and oxygen liberated in the electrolysis of water, we find that the oxygen weighs 8 times as much as the hydrogen. 6. The volume of ice is greater than that of the same weight of water. 7. That the solid dissolves in water can be found by a number of ways. 8. You can use any sample in your work.

Ex. 20. Open the brackets choosing the correct forms of the Participles:

1. When (heating, having heated) this substance, one should be very careful. 2. (Investigated, having investigated, investigating) all the properties of new water, they could understand the mistery of silvery clouds. 3. The (dissolving, dissolved, having dissolved) materials may be soluble solids, liquids or gases. 4. Water (using, used, having used) in steam boilers, should be free from substances that cause corrosion.

5. (Purified, having purified, purifying) the water from the substance that cause corrosion, we can use it in steam boilers.

Ex. 21. Translate the following into English:

1. Сравнивая их с газами, мы видим . . .

2. Выполнив (проведя) ряд исследований, ученые . . .

3. Продолжив свою работу, . . .

4. Дождевая вода, образованная конденсацией водяного пара, . . .

5. Проведя точное определение состава воды, . . ,

Ех. 22. Read the text fluently and render it:

Salts are insoluble in most solvents but they are soluble in water. Gasoline, benzene, carbon disulphide are good solvents for grease, rubber, organic materials generally, but they do not dissolve salts.

The reason that water is so effective for salts is that it has a very high dielectric constant and its molecules tend to combine with ions forming hydrated ions. Both of these properties are due to the large electric dipole moment of the water molecule. Having studied these properties, we can understand that water molecule has a considerable amount of ionic character.

Ex. 23. Read the text and retell it:

Liquid water in thin layers is colourless, but in deep layers it has a bluish colour.

Pure water is odourless and tasteless. Natural waters have taste because of the presence of dissolved substances. Water is a poor conductor of electric current.

Several common units of measurement are defined in terms of the properties of water. The melting point of ice and the boiling point of water at a pressure of one atmosphere were selected arbitrarily.

Ex. 24. Translate the text, answer the questions that follow and retell the text:

Soviet scientists have discovered water having amazing properties. It is 50 per cent heavier than ordinary water. It boils not at 100° but 50°C.

The chemical structure of this water is the same as that of the water which we drink. It is also composed of two atoms of hydrogen and one of oxygen.

The Soviet physicists have noticed that this water becomes condensed in thin capillary glass tubes. Such a phenomenon can happen if the chamber in which the experiment was carried out was saturated with vapour. But in this case there was little vapour and it became clear that it was unusual water. This water had quite different new properties, e.g. its viscosity was Л5 times greater than that of ordinary water. It froze at 40°-50°C below zero.

Having investigated all the properties of this water, the scientists can solve the riddle of the special silvery clouds, which can be found at an altitude of 80 km, i.e. 10 times higher than the usual ones.

1. What have Soviet scientists discovered?

2. What are the properties of this water?

3. How many atoms is this water composed of?

4. What have the Soviet physicists noticed?

5. What new properties has this water?

„ 6. What riddle will our scientists be able to solve?

У

/ Ex. 25. Write the translation of the following text:

A related effect which stabilizes the dissolved ions is the formation of hydrates of the ions. Each negative ion attracts the positive ends of the adjacent water molecules, and tends to hold several water molecules attached to itself. The positive ions show the effect still more strongly; each positive ion at­tracts the negative ends of the water molecules, and binds sev­

eral molecules about itself, forming a hydrate which may.have considerable stability.

The number of water molecules attached to a cation is v determined by the size of the cation. The forces between cations and water molecules are so strong that ions often retain a layer of water molecules in crystals. This water is referred to as water of crystallization.

Grammar: The Absolute Participle Construction, Text: Isotopes.

LESSON 14

isotope ['aisotoup] hence [hens] frequently ['fri:kwontli] identical [ai'dentikol] alpha rays ['aelfo 'reiz] beta rays ['bi:to 'reiz] diverse [dai'vo’.s]

instrumental [^nstru'mentl] diagnosing ^daiag'nouzig] extent [iks'tent] machine [mo'JTm] dismantling [dis'maentlipj

Ex. 1. Pronounce the following words:

Ex. 2. Read the following word combinations:

considerably great frequency [kon'sidorobli 'greit 'fri:kw9nsij

groups of atoms ['gru:ps ov 'aetomz]

identical with [ai'dentikol wi3]

tremendous energies [tri'mendos 'en^iz]

stable isotopes ['steibl 'aisotoups]

deepest secrets ['di;past 'si:krit$]

extent of wear [iks'tent ov 'wea]

new uses of isotopes ['nju: 'ju:siz ov 'aisotoups]

Ex. 3. Change the sentences according to the given models:

Model I: As my work is very difficult, he helps me.

My work being very difficult, he helps me.

1. As the range of application of stable isotopes is very wide, the scientists are greatly interested in it. 2. As this machine works well, we can use it at our plant. 3. Since the speed of light is extremely great, we cannot measure it by ordinary means. 4. As their lectures begin in the morning, they are free at five o’clock.

Model II: When radioactivity had been discovered,

science made great progress in atomic physics. Radioactivity having been discovered, sci­ence made great progress in atomic physics.

1. When all the properties of the element had been discov­ered, it was much easier to use it. 2. After the new computer had been built, they could calculate the acceleration of the particles. 3. When the solution had been evaporated, they began to examine the residue left.

Ex. 4. Compare the following pairs of sentences and translate them into Russian:

1. This scientist being in our country got interested in our system of educati on.

D. I. Mendeleyev being a great chemist, his name is well known not only in the USSR but also abroad.

2. Having carried out a series of analyses, he could make some interesting conclusions.

The scientist having carried out his investigations in the laboratory, we could ask him about the results.

3. The phenomenon discovered by him helped us greatly in our research work.

The melting point having been discovered, it was possible to continue our research work.

4. A solution containing no excess of either acid or basic hy­droxide is known as a neutral solution.

A solution containing no excess of an acid or basic hydro­xide, we can call it a neutral one.

Ex. 5. Pay attention to the translation of the following verbs and remem­ber them:

to give—давать to give out — выделять

to give rise to—вызывать, обуслов­ливать

to find — находить to find out — выяснять, узнавать to make—делать to make up—составлять