663
.pdfwater becomes ice or steam, there is no change in the chemical nature of the substance. 7. No animal can live without oxygen. 8. No significant relationship in the properties of solutions can be noticed.
LESSON VII.
Notes on theText.
1.in contrast to - B npoT~BonoIlO>KHoCTb
2.any given sample - IlIo6o~ ~MeIOLLt~~C51 06pa3eL\
3.one and a half times - B nOIlTopa pa3a
4.index of refraction - K03CPCP~L\~eHT npeIloMIleH~51
5.10 times larger - B 10 pa3 60Ilbwe
T E X T . SUPERDENSE WATER.
I.
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 not 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 centimeter 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
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stable form of water having the density almost one and a half times that of ordinary water was obtained. This water was named Water 11. Having examined its properties they found out that its index of refraction was equal to about 1.48 to 1.49. But when Water 11 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 11 was equal to that of pure water. Then it was very important to learn the stability of the molecules of Water 11 and the forces responsible for their stability.
It was assumed that under the impact of the electrons on the molecules of Water 11, these molecules are immediately broken down into ordinary molecules of H20. And that Water 11 in solution has a definite molecular weight that is approximately 10 times larger 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 11 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.
11.
Water is hydrogen oxide, a compound of hydrogen and oxygen. It can be made if hydrogen or a hydrogencontaining substance are burnt in air or oxygen.
Most of the world'swater is liquid, but an important
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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 (satutated with air at 1 atm pressure) is taken as OOC 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°C(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 |
|
|
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Invariant |
stable |
to attract |
To compare |
that |
future |
Slightly |
to dilute |
to burn |
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 |
approximately |
environment |
To cause |
|
to remain |
Ex.1. Give the Russian equivalents of the following:
1.Having compared these two substances,... 2. When comparing these substances... 3. When compared, these substances... 4. Comparing these substances... 5. Having examined this element, ...
6. If examined, this mineral... 7. Examining this liquid ... 8. While examining this liquid... 9. The substance examined...
Ex.2. Translate the sentences, mind the word "that": Not e: that - TOT, Ta, TO (yKa3.Mecm.)
'"ITO(COI03)
KOTOPbl~ (omHocum. Mecm.) cnoeo-3aMeHumenb cyU(ecmeumenbHoao
1.We know that in all chemical reactions the weight of the substances that are reacting is equal to weight of the products obtained. 2. The concentration of iodine in the ether layer is approximately 200 times that of the water layer. 3. A rise in temperature increases the velocity of the endothermic reaction more than that of the exothermic reaction. 4. The
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number of molecules of water is twice that of molecules of oxygen from which it is produced, that is each oxygen molecule is split into two equal reactive units. 5. The solid that was used is highly soluble in water. 6. The density of ice is lower than that of liquid. 7. A gram molecular weight of a gas is that weight which occupies the same volume as 32 grams of oxygen at the same temperature and pressure.
Ex.3. Read the text fluently and render it:
Sals 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. 4. 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.
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Ex. 5. 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 15 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?
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LESSON VIII.
Notes on the Text
1.in the case of uranium - ecm1 Mbl VlMeeM AeIlo c ypaHoM (8 cIly"lae c ypaHoM)
2.regular atoms - 06bl"lHble aTOMbl
3.to be of great significance - VlMeTb 60Ilbwoe 3Ha"leHVle
T E X T . ISOTOPES.
The word "isotope" is derived from the Greek "isos", "topos" and means the same place.
Hence, isotopes are atoms having the same atomic number, but differing in atomic weight (mass number), e.g. lie and lie are isotopes of carbon, or one out of every
5,000 atoms of hydrogen has an atomic weight of 2.016 instead of 1.008.
This odd atom has a neutron in its nucleus as well as a proton, it being known as heavy hydrogen. The water containing it is known as heavy water.
Isotopes occur with considerably greater frequency in other elements than in hydrogen, an extreme case being chlorine, its atomic weight being 35.5. It is made up of two groups of atoms in a radio of 3:1, the weight of one group being 35, that of the other 37.
In the case of uranium, for example, one isotope of atomic weight 235 is found in every 140 atoms of the standard weight, with the weight being 238.
The chemical properties of isotopes being identical with those of regular atoms, their discovery was of little interest to chemists. Physicists, however, got interested in them, a new way of approaching to the structure of matter being opened.
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Radioactive and Stable Isotopes.
The use of new atomic power sources of tremendous energies is of great significance.
However, a part of no lesser importance is played by radioactive and stable isotopes obtained in nuclear reactors and accelerators, almost every chemical element having a number of isotopes.
At present about 1,000 artificial radioactive isotopes emitting alpha, beta and gamma rays, and about 300 stable (Le. non-emitting) isotopes of all elements of
Mendeleyev'sPeriodic System are known.
Production of artificial radioactive isotopes has developed into a new industry, while their application has become so wide and diverse that one can hardly name a branch where they are not or cannot be used.
Thus when used by doctors, radiation of radioactive isotopes is instrumental in diagnosing and curing diseases. When used by scientists they are helpful in penetrating into the deepest secrets of some processes.
Biologists have succeeded in breeding new varieties of microorganisms producing large quantities of most valuable antibiotics.
By using isotopes the control of the pig-iron and steel production process can be made simpler and cheaper.
By means of isotopes it is possible to control the extent of wear of cutting tools or machine parts while in operation without stopping or dismantling them. All this gave rise to new investigations of still more new uses of isotopes.
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Remember the following words:
To derive |
Source |
Derivative |
To accelerate |
Extreme |
Accelerator |
To make up |
To succeed |
Identical |
Pig-iron |
Diverse |
By means of |
Regular |
Extent |
To approach |
To give rise to |
Ex.1. Compare the following pairs of sentences and translate them into Russian:
1.This scientist being in our country got interested in our system of education. D.I.Mendeleyev being a great chemist, his name is well known not only in Russia 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.2. Translate the following sentences, mind the Absolute Participle Construction:
1.The experiment being very interesting, we work readily.
2.The range of application of stable isotopes being very wide, the scientists are interested in them. 3. The electron
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is about as large as a nucleus, its diameter being about 10-12 cm. 4. Ordinary salt being examined with a magnifying glass, they saw that the crystals were of cubic form. 5. A gas can be dissolved in a liquid, the liquid changing its boiling point. 6. The elements having been arranged in the Periodic Table, it became easier to predict new elements. 7. The experiment being time-consuming, he has to spend much time in the laboratory. 8. Simple substances consist of atoms, each substance having its own special atom.
LESSON IX.
Notes on the Text.
1. the investigations are known to have yielded... -
L-13BeCTHO, '-ITOL-1CClleAOBaHL-1~ AallL-1 ...
2.a final product - KOHe'-lHbl~ npoAYKT
3.this glass was found to differ - 6blllO
o6HapY>KeHO, '-ITO3TO cTeKllO OTllW·laeTC~
4. it was the logical outcome - 3TO 6blJlO IlOrL-1'-1eCKL-1MClleACTBL-1eM (pe3YllbTaToM)
5.far lower - ropa3Ao HL-1>Ke
6.they can be classed with - L-1X MO>KHO nOCTaBL-1Tb B
OAL-1H P~A
T E X T . SOME SEMICONDUCTING MATERIALS.
It was the Physico-Technicallnstitute in Leningrad that first began investigating solid solutions of semiconducting compounds such as metal sulphides, selenides and tellurides. The object of the research was to obtain new semiconducting materials for the industry.
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