X. Прочтите и переведите текст А
Text A. Compounds of Sodium and Potassium
The alkali metals — lithium, sodium, potassium, rubidium, and caesium—which fall in Group I of the Periodic Classification, are the most strongly electro-positive elements known. They are all univalent, and their compounds are soluble in water. The metals themselves are distinguished by their great affinity for oxygen. They undergo oxidation rapidly on exposure to air and decompose water readily in the cold, with evolution of hydrogen and formation of soluble, strongly alkaline hydroxides. All these characteristics are most marked in caesium, and least in lithium.
Sodium and potassium compounds are widely distributed and abundant. Lithium compounds are found in comparatively small quantities, and rubidium and caesium are decidedly rare elements. The compounds of sodium and potassium are very widely employed in pharmacy, and corresponding compounds of the two metals are similar in therapeutic action.
Compounds of sodium. The chief naturally occurring compound of sodium is the chloride, NaCL, which is present in sea-water to the extent of 2 to 3 per cent, and is also found as rock salt.
The manufacture of sodium carbonate, sodium bicarbonate, and sodium hydroxide forms the chief branch of the great alkali industry. Most of the sodium salts used in pharmacy are made from the carbonate or hydroxide.
Sodium hydroxide. Contains not less than 95.0 per cent of total alkali, calculated as NaOH, and not more than 2.5 percent of Na2CO3.
Sodium hydroxide is manufactured by heating sodium carbonate with water and lime in large iron tanks.
Most of the sodium carbonate produced at the present day is manufactured by the ammonia-soda process. The principle of the method is simple. Strong brine containing a high concentration of ammonia is passed through a "carbonating tower" where it is saturated with carbon dioxide under pressure. The ammonia and carbon dioxide decomposition with the sodium chloride causes the precipitation of sodium bicarbonate, which is not very soluble in water, and is still less soluble in brine.
Words:
1. affinity — хим. сродство. Здесь: Эти металлы распознаются по их свойству легко соединяться с кислородом
2. on exposure to air — под действием воздуха
3. iron tanks — металлические емкости
4. "carbonating tower" - «углеродная колонка». (Кавычки означают, что словосочетание не является термином, а используется терминологически в данном тексте)
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5. sodium and potassium – натрий и калий
XI . Answer the questions:
1. What kind of metals are lithium, sodium, potassium and caesium?
2. In what group of the Periodic Classification do these metals fall?
3. When do these metals undergo oxidation rapidly?
4. Why are sodium and potassium compounds of great importance in pharmacy?
5. What compounds are found in comparatively small quantities?
6. What is the chief naturally occurring compound of sodium?
7. How is sodium hydroxide manufactured at present?
TASKS
I. Read and translate the text B:
Text B. Proteins and Amino-Acids
Proteins are highly complex compounds elaborated by living cells, and containing the elements of carbon, hydrogen, oxygen, nitrogen, and usually sulphur. They are particularly important as the source of combined nitrogen in foodstuffs. The percentage of nitrogen in most proteins varies from about 15 to 19.
Proteins are classified chiefly according to their solubility; thus albumins are soluble in water while globulins are insoluble in water but soluble in dilute salt solutions. Both albumins and globulins are coagulated by heat. The molecular weights of proteins are known to be estimated only approximately, but investigations by ultracentrifugal methods give results for the soluble proteins varying from a few thousands to many millions. Those proteins which are soluble form colloidal solutions which are generally viscous and may form gels if sufficiently concentrated (e. g. gelatin). From their colloidal solutions many proteins are precipitated by electrolytes. Many of them (e. g. egg albumen) are coagulated by heat. When the temperature is above 60 — 80 °C it produces a marked change in protein structure. This is an example of "denaturation", with diminution in solubility and other changes in properties, which may be brought
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about in proteins by various means, including the action of reagents. Substances of such high complexity would not be expected to crystallize under ordinary conditions; nevertheless, some proteins, including egg albumin and hemoglobin, can be obtained in crystalline form by special methods.
Proteins can be hydrolyzed with formation of simpler substances. This process takes place, for example, during digestion in the stomach and intestinal tract.
Amino-acids represent the final stage of protein hydrolysis, and many different amino-acids are produced by the breakdown of a single protein.
The substances intermediate between proteins and amino-acids are not sharply differentiated from one another, since the breaking down process is a gradual one. The progressive decrease in molecular complexity on hydrolysis is accompanied by a corresponding increase in solubility and tendency to crystallization.
Note:
1. the breakdown of a single protein — распад (разложение) белка одного вида
II. Find the equivalents of the words in brackets:
1. Proteins are highly complex compounds (вырабатываемые) by living cells. 2. The percentage of nitrogen in most proteins (варьирует) from about 15 to 19. 3. The molecular weights of proteins can be estimated only (приблизительно). 4. Many proteins are precipitated by (электролитами). 5. The substances intermediate between proteins and amino-acids (не очень резко отличаются) from one another. 6. Proteins can be hydrolyzed (с образованием более простых веществ). 7. Amino-acids (представляют собой) the final stage of protein hydrolysis.
III. Answer the questions:
1. What kind of compounds are proteins?
2. What are they elaborated by?
3. What chemical elements do proteins contain?
4. How does the percentage of nitrogen in most proteins vary?
5. How can the molecular weights of proteins be estimated?
6. What methods of investigations of proteins do you know?
7. What stage of protein hydrolysis do amino-acids represent?
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8. What happens to proteins during digestion in the stomach and intestinal tract?
9. Why are substances intermediate between proteins and amino-acids not sharply differentiated from one another?
IV. Communicative situations:
1. Imagine you are a lecturer in Pharmaceutical chemistry. Give an introductory lecture about the significance of pharmaceutical chemistry, the importance of this industry to public health.
2. Write down all possible word – combinations a) adj+n; b) v+n:
a). coastal, radioactive, medical, industrial, organic, urban; to cause, to exceed, to discharge;
b). waters, standards, death, areas, problems, matter, contamination, wastes.
3. Prepare a short report “History of the Peroidic Table”. Use the following words:
Contribution to chemistry, the Russian Chemical Society, increasing atomic weight, chemical and physical properties, valence, protons, to order elements according to … , to gain recognition.
TEST
Choose a right variant:
1. water occurS … in nature.
1) only in solid and vapour condition
2) only in liquid condition
3) only in liquid and solid condition
4) in liquid, solid and vapour condition
2. The human body is composed of more than ..... of water.
1) 90 per cent
2) 86 per cent
3) 70 per cent
4) 96 per cent
3. We …. water for drinking and domestic purposes every day.
1) are using
2) uses
3) use
4) do use
4. GOOD DRINKING WATER MUST BE FREE FROM…
1) toxic salts only
2) salts of calcium and iron
3) magnesium, potassium, and sodium
4) toxic salts, disease producing organisms, harmful organic and sewage contamination
5. .… OF THE EARTH SURFACE ARE COVERED WITH LIQUID WATER.
1) a half
2) northern part
3) about 3 quarters
4) southern part
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6. ABSOLUTELY PURE WATER DOES NOT OCCUR IN NATURE.
1) that’s wrong
2) that’s right
3) I don’t know
4) I’m not sure
7. THE NUMBER OF POSSIBLE COMPOUNDS IS …
1) limited
2) definite
3) infinite
4) well-known
8. … ARE HIGHLY COMPLEX COMPOUNDS ELABORATED BY LIVING CELLS.
1) penicillins
2) proteins
3) antibiotics
4) sulfa drugs
9. … ARE CLASSIFIED CHIEFLY ACCORDING TO THEIR SOLUBILITY.
1) salts
2) proteins
3) acids
4) all chemical elements
10. COMPOUNDS OF SODIUM AND POTASSIUM ARE … IN THERAPEUTIC ACTION.
1) different
2) unknown
3) various
4) similar
LESSON 7
Грамматика: модальные глаголы; числительные
CLASSIFICATION OF ELEMENTS
Запомните: суффикс -alобразует прилагательные от основ существительных;
суффикс – ic образует прилагательные от основ существительных
I. 1. Прочитайте и переведите:
experimental, practical, social, medical, natural, chemical, logical, capable, clinical, cerebral, neutral, abnormal
2. Прочитайте и переведите:
carbonic, phenolic, alcoholic, electronic, basic, prophylactic, anatomic, democratic, economic, atomic, mercuric, organic
3. Назовите исходные формы следующих производных слов, слова переведите:
clinical, preparation, successfully, effectiveness, decision, government, chemical, possibility, treatment, different, desirable, completely, therapeutic, toxicity, depressant
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