English for chemists

Lesson 24
ГРАММАТИКА: Повторение тем «Подлежащее» и «Дополнение»
Section I
Ex. 1. Practise your pronunciation.
a) recognize ['rekagnaiz], relative [‘relotiv], carefully [‘keofuli], determine [df t3:min], electrolysis [ilek'trohsis], unique [ju:'mk], subsequent ['sAbsikwont], aqueous ['eikwios], observation [.obzs'veijbn], isolate [’aisolctt], phase [fcizj, hybridize ['hatbndaiz]
. b) is j burnedJn\air, 'weight^ofNoxygen, the a'mount^ofshydrogen, withy'thesejobser'vations, 'neighbouring^'water Smolccules

c) 'Water was 'thought by the/"ancicnts | to be an\clcmcnt.

Ex. 2. Pay attention to the structure of the following words. Translate them into Russian.

1. 
   undergo, underestimate, underdeveloped, undergraduate, underground, underline, understand
   

2. 
   misunderstand, misadvise, misbehave, miscalculate, misconccption,
   

mishandle, mishear, misinform, mispronounce, mistake

c) semiautomatic, semiconductor, semiannual, semifluid

б Схемном 161

Ex. 3. Define the meanings of the word both in the following scntcnccs:
1. Combustion is a chcmical reaction which takes place with the evolution of both light and heat. 2. As to sulphur and oxygen, it should be noted that both of these elements have allotropic modifications. 3. Which of the two seasons do you like better— summer or autumn?— As for me, I like both. 4. Solutions arc very important kinds of matter— both for industry and for life. 5. Both of the substanccs (barium sulphate and silicon dioxide) arc practically insoluble in water. 6. What is the matter with M and N, they both arc absent again? 7. Both sodium and potassium belong to the same family of elements, it is not surprising that they have similar properties.
Ex. 4. Find the predicate, the subject and the object in the following sentences:
1. Lavoisier first recognized that water is a compound of the two elements, hydrogen and oxygen. 2. The structure of water must be fundamentally different from that of most other liquids. 3. The characteristic increase in the density of water with temperature is found to continue until 4°C.
Text 24 A
The Composition and Structure of Water
Water was thought by the ancients to be an element. Henry Cavendish in 1781 showed that water is formed when hydrogen is burned in air, and Lavoisier first rccognizcd that water is a compound of the two elements — hydrogen and oxygen.
The formula of water is H20 . The relative weights of hydrogen and oxygen in the substancc have been very carefully determined as 2.016:16.000. This determination has been made both by weighing the amounts of hydrogen and oxygen liberated from water by electrolysis and by determining the weights of hydrogen and oxygen that combine to form water.
Liquid water has a number of unique properties which indicate that the structure must be fundamentally different from that of most other liquids. Thus, water has high melting and boiling points, an unusually high heat capacity, and shows a characteristic decrease in molar volume on melting and a subsequent contraction between 0 and 4°C. Quite apart from the behaviour of aqueous solutions, any proposed structure for liquid water must be consistent with these observations.
From spcctroscopic studies of isolated water molcculcs in the gas phase, it has been shown that the H—О—H bond angle is very nearly the tetrahedral angle of 105° and the О—H intcmuclcar distance is 0.97E; the observed dipole moment is 1.87x10 '1* c.s.u.* acting along the biscctor of the H—О—H angle.
* e.s.u. — clcctrostatic unit

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Bcmal and Fowler in a classical work on the interpretation of these results, showed that the net clcctronic density distribution was consistent with such a structure in which, in addition to the two protons carrying small positive chargcs, there arc also two regions of negative charge. These four regions of charge, two positive and two negative, could be regarded as residing at the corners of a tetrahedron. If the oxygen is approximately sp3 hybridized then two of the orbitals on the oxygen atom arc used for bonding the hydrogen atoms and the other two cany the lone pairs of electrons which can participate in hydrogen bonds to two neighbouring water molcculcs. In terms of this picture the structure of ice, in which each molcculc has four nearest neighbours, can be represented in the following way. The molcculcs arc held together by tctrahcdrally-dirccted hydrogen bonds which arc essentially clcctrostatic in charactcr. The structure is an open one rather than a close-packed with a resulting increase in density. The characteristic increase in density with temperature continues until 4°C when die cxpcctcd decrease accompanying the increased thermal energy becomes apparent.
Words and Word-Combinations to Be Memorized
accompany, apart, apparent, aqueous, behaviour, capacity, careful, character, charge, consistent, dipole, energy, expect, liberate, moment, net, a number of, observation, partial, participate, positive, region, spcctroscopc, static, unusually
Ex. 5. Give the Russian equivalents for the following:
. relative weights, determine very carefully, liberate hydrogen, a number

• 
  of unique properties, heat capacity, the behaviour of aqueous solutions, be consistent with, spectroscopic studies, the bond angle, the interpretation of results, in addition to the protons, positive charge, at the comers of a tetrahedron, participate in hydrogen bonds, represent the structure, be electrostatic in charactcr, thermal energy
  

Ex. 6. Give the English equivalents for the following:

состав воды, на воздухе, признавать, жидкая вода, отличаться от, высокие точки плавления и кипения, необычно высокая теплоемкость, в газовой фазе, мсжъядсрнос расстояние, классическая работа, отри­ цательный заряд, водородная связь, соседние молекулы воды, струк­ тура льда, следующим образом, удерживать вместе, быть каким-л. по характеру, а не частичное разрушение структуры, увеличение плот­ ности, ожидаемое уменьшение, становиться очевидным
Ex. 7. Fill in the blanks with prepositions where necessary.
1. Cavendish ... 1781 showed water to be formed when oxygen is burned ... air. 2. The relative weights ... hydrogen and oxygen ... the substancc were very carefully determined. 3. Water ... the liquid phase has a number... unique properties. 4. The structure ... water is different

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... that... most... other liquids. 5. It was shown ... spcctroscopic studies that the H—О—H bond angle is very nearly the tetrahedral angle... 105°. 6. The molcculcs ... icc arc held together ... tetrahcdrally-directcd hydrogen bonds. 7. These bonds arc essentially electrostatic ... charactcr.
Ex. 8. Translate the scntcnccs into Russian, paying attention to different functions of the word will.
1. The laboratory of analytical chcmistry will soon be transferred to a new building. 2. Heating will affcct the state of water but not its composition. 3. Other ways of obtaining hydrogen willbc discusscd in the next chaptcr. 4. Water is usually callcd a universal solvent bccausc it will dissolve a tremendous number of substanccs. 5. Will you give me your dictionary for a couplc of days? 6. He went to the university against his father’s will. 7. There will be no difficulty in making calculations.
Ex. 9. Translate the sentences into Russian.
1. That air is not a chcmical compound is now known even to children, but there was a time when it was thought to be an clement. 2. The chcmists have many problems to solve, particularly environmental ones. 3. One

has to remember that a reaction with the liberation of heat may be followed by an explosion. 4. It is sometimes not easy to decide what catalyst should be used. 5. For a number of chcmical processes it is desirable to use distilled water. 6. To obtain sufficiently pure water is one of the urgent problems of the day, especially in chcmical and paper industries. 7. Boiling is one of the simplest ways of purifying water. 8. Barium sulphate is only slightly soluble, one can easily separate it by means of a filter. 9. They watchcd the temperature rising, but at the temperature of 69 degrees the proccss stopped. 10. Phosphorus is very interesting by existing in several allotropic forms. 11. Never take white phosphorus with bare hands bccausc heat of the body is enough to ignite it. 12. It is its activity with oxygen that is the most striking property of phosphorus. 13. Compounds of silicon arc found to make up about 87 per ccnt of the outer layer of the solid earth. 14. Atoms arc generally known to be electrically neutral. 15. Hydrogen atom is stated to contain no neutrons. 16. They supposed the substancc to react at room temperature, but it wouldn’t. 17. Combining the two mixtures may result in an explosion. 18. To find free chlorinc in nature is impossible bccausc of its exceedingly high activity. 19. Chlorinc is considered to be a typical non-metal. 20. For hydrogen to combinc with chlorinc with appreciable velocity in the dark is possible in the presence of a catalyst. 21. The experiments show chlorinc to be an activc oxidizing agent. 22. That the lightest of the alkali metals is lithium can be determined by its position in the periodic table. 23. One can observe caesium taking fire at ordinary temperature. 24. Molccular structure of nitrogen allows the properties of this element to be accounted for. 25. Nitrogen can be made to form ammonia by use of a suitable catalyst. 26. Whether the hypothesis is

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true must be verified experimentally. 27. The aim of this experiment is to show whether sulphuric acid will react with metals. 28. Lomonosov's being the first who formulated the second law of thermodynamics is seldom mentioned. 29. It is heating that forces many reactions to take place. 30. A great number of elements have been found to have two or more isotopes.
Ex. 10. Translate the sentences into English.

1. 
   В древние времена считали, что вода— это одни из элементов.
   

2. 
   Только в конце XVIII столетия было доказано, что вода состоит из двух элементов — водорода и кислорода. 3. Теперь каждому школь­ нику известно, что формула воды — Н20 . 4. Вода в жидком состоя­ нии обладает рядом уникальных свойств. S. То, что вода — необычная ж и д к о с т ь , объясняется ее структурой, б. Интересно также изучение
   

воды в газообразной и твердой фазе. 7. Характерными физическими свойствами воды можно назвать высокие точки плавления и кипе­ ния, а также теплоемкость.

Ex. 11. Answer the following questions:

1. 
   By means of what experiment was it shown that water is a compound?
   

2. 
   What is the composition of water? 3. What properties show water to be a unique liquid? 4. In what way can the properties of water be accounted for? 5. What did spectroscopic studies of water molcculcs show? 6. In what way arc the atoms in the water moleculc held together?