Санкт-петербургского государственного университета высшее профессиональное образование т. А. Степанова, И. Ю. Ступина
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1stepanova t a english for chemists
| Lesson 27
ГРАММАТИКА: Инфинитив и инфинитивный оборот в функции опре деления. Придаточное предложение в функции опре деления. Section I Ex. 1. Practise your reading. It is often true that the most common conccpts wc use arc the most difficult to define prcciscly. Ex. 2. State what parts of speech the following words belong to: solution, solute, solvent, soluble, solubility, solubilization, dissolve, dissolvable, dissolution, insoluble, solvation Ex. 3. Define the meanings of the word either in the following sentences: I .Either of these techniques may be used at high temperatures. 2. There arc substanccs that cannot be clcarly classified either as solutions or as mixtures. 3. A solution of soap in water has properties and composition which might be described as either inhomogeneous or homogeneous depending on the experiment wc do. 4. Chlorinc docs not bum either in air or in pure oxygen. 5. Either of the elements of Group IA o f the periodic tabic has a single electron in the outermost level. 6. This is a very useful reference book, I wish 1 had it in my library. — I haven’t got it either. 7. There are three journals on the table, you may take either o f them. Ex. 4. Analyse the following sentence: One must know the purity of a chemical to be used in the reaction. Text 27 A The Properties of Solutions It is difficult to give a definition which tells clcarly and briefly how ■c solutions differ from mixtures and compounds, in spite of the fact that solutions arc among the most familiar substances to be found in nature. However, it is often true that the most common conccpts wc use are the most difficult to define prcciscly. A solution is a homogeneous substance that has, over ccrtain limits, a continuously variable composition. The word “homogeneous” sets a true solution apart from a mechanical mixture, for mixtures have macroscopic regions which have distinct and different composition and properties. The properties and composition o f a solution arc uniform, as long as the solution is not examined at the molccular level. There arc substanccs, however, not to be clcarly classified as solutions or 179 mixtures. A solution of soap in water has a cloudy appcaiancc due to particles which consist of many soap molcculcs collected together. Such a substancc has properties and composition which might be described as either inhomogcncous or homogeneous depending on die experiment to be done. Therefore, there is no sharp dividing line between mixtures and solutions. The requirement that solutions have continuously variable composition distinguishes them from most compounds. However, many solid materials wc commonly think of as compounds actually show variable composition. Cuprous sulphide and ferrous oxide arc examples of compounds which might also be thought of as solutions. No matter how carefully wc made our definitions of solution, mixture, and compound, wc must expect to find certain substanccs not to be uniquely classified as one of these. There is no reason to cxpcct nature to be cooperative and producc only substanccs which are easily classified, and sincc this is the case, the most useful definitions are often the shortest, rather than the most exhaustive. Words and Word-Combinations to Be Memorized actually, appcarancc, brief, briefly, this is the case, certain, classify, clearly, continuously, depending on, distinct, examine, familiar, ferrous, for, homogeneous, level, as long as, mechanical, no matter, precisely, requirement, to set, uniform, variable Ex. 5. Give the Russian equivalents for the following: to give a definition, to tell clearly and briefly, in spite of tlic fact, it is often true, the most common concepts, over certain limits, as long as, a cloudy appcarancc, the experiment to be done, a sharp dividing line, no matter how carefully, sincc this is the ease Ex. 6. Give the English equivalents for the following: отличаться от, свойства растворов, вещества, которые можно найти в природе, точно определить, гомогенное вещество, переменный со* став, исследовать на молекулярном уровне, четко классифицировать, в зависимости от эксперимента, нет оснований ожидать Ex. 7. Fill in the blanks with articles where necessary. 1. It is rather difficult to give ... definition o f ... solution. 2.... word “homogeneous'* sets ... true solution from ... mechanical mixture. 3— ferrous oxide i s ... example o f ... compounds wc may consider as ... solution. 4. ... most useful definitions arc often ... shortest. 5. At ... molccular level... properties o f ... solutions are not examined well enough. Ex. 8. Give synonyms for the following: precisely, distinct, different, examine, however, due to, consist of, many, do, material, commonly, actually, show, also, sincc 180 difficult, familiar, often, apart, different, short, most, certain, variable Ex. 10. Translate the scntcnccs into Russian. 1. Professor N was the first to prepare this kind of glass clcctrodcs in our laboratory. 2. They stayed at the laboratory till 8 in the evening, bccausc they had a lot of work to do. 3. There arc two points to discuss. 4. Tins is the condition for everybody to observe. 5. There arc some rules never to be forgotten. 6. Students who study chcmistry must Icam to do experiments. 7. Here is the room where chemicals arc stored. 8. The need often arises in chcmical research to measure die concentration of a solution with a high degree of precision. 9. A student about to begin an experiment must get his supervisor’s permission. 10. The substancc to be dissolved is callcd die solute. 11. There arc a lot of problems for chemists to solve. 12. Acids arc chemicals to be used carefully. 13. Not the least of D. I. Mendeleyev’s services to chcmistry was his publication of the first text-book of chcmistry to be based throughout on the periodic system of classification. 14. John Dalton was by no means the first to speculate about an atomic theory. 1 S. Lavoisier was the first to realize the importance of the balancc for chcmical investigation. 16. D. I. Mendeleyev was the first Russian chemist to receive widespread recognition in the West during his lifetime. 17. The first clement of the series of noble gases to be discovered was argon. 18. Oxygen is frequently chosen as one of the first elements to be studied in chcmistry. 19. The rise of temperature gives more opportunity for the molcculcs to react. 20. There is usually a limit to how much solute a given volume of solvent can hold at a given temperature. 21. Compounds have properties that differ from those of the constituent elements. 22. Wc arc living at a time when chcmistry is used almost everywhere. 23. The periodic law D. I. Mendeleyev discovered created a new era in the history of chemistry. 24. The question whether a particular gas is lighter or heavier than air can be easily solved. 25. The state of a p substancc depends usually on die temperature and pressure it is subjected to. 26. The elements water is composed of arc hydrogen and oxygen. 27. The first element wc shall study in detail is oxygen. 28. It is recommended that water wc use for drinking should be boiled. 29. It often happens that the necessary condition for the reaction to begin is the presence of a catalyst. 30. It is the usual laboratory practice that the potassium chlorate oxygen is to be produced from is placed in a vessel and heated. Ex. 11. Translate the scntcnccs into English without using a dictionary. 1. На вопрос о том, чем растворы отличаются от смесей, не всегда легко ответить. 2. Среди веществ, которые можно найти в природе, немало растворов. 3. Свойство гомогенности позволяет отличить ис тинный раствор от механической смеси. 4. Некоторые свойства ра створов можно объяснить только на молекулярном уровне. 5. Нет оснований полагать, что вещества, которые мы находим в природе, всегда легко классифицировать. Ex. 9. Give antonyms for the following: 181 1. Why is it difficult to give a definition of a solution? 2. Solutions arc among the least known substanccs, aren't they? 3. What is usually considered as the main property of solutions? 4. In what way can you characterize a solution of soap in water? 5. Can one easily classify substanccs to be found in nature? 6. What definitions arc the most useful? жүктеу/скачать 5,96 Mb. Достарыңызбен бөлісу:
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