The Action of Chlorine on Other Elements

At ordinary temperatures chlorine is a pale green gas, with normal boiling and freezing points of -35° and -102°, respectively. It occurs in nature mainly as sodium chloride. Chlorine is prepared in very large quantities industrially. It is moderately¹ soluble in water. Dry chlorine is somewhat inert chemically and it has no appreciable action upon bright metallic sodium, copper, etc. Moist chlorine is very active. It does not combine with oxygen directly, although several compounds of chlorine and oxygen can be obtained indirectly. In sunlight, equal volumes of hydrogen and chlorine combine with explosion, whereas in the dark hydrogen does not appear to combine with chlorine with appreciable velocity. Chlorine oxides are highly reactive and unstable, they are likely to explode under various conditions. Probably the best characterized is chlorine monoxide Cl₂O. It is a yellowish red gas at room temperature, the liquid boiling at 2°C. It explodes rather easily on heating. It is known to dissolve in water forming an orange-yellow solution. Chlorine dioxide is also highly reactive and likely to explode very violently.

Примечание к тексту

1. moderately – умеренно

VIII. Изложите содержание текста на английском языке.

LESSON 10

Грамматика. Инфинитив в функции подлежащего и обстоятельства (цели и следствия).

Предтекстовые упражнения

I. Обратите внимание на функцию инфинитива в следующих предложениях и переведите предложения на русский язык:

1. To separate air into its components requires the use of fractional distillation of liquid air. 2. To separate air into its components one must use fractional distillation of liquid air. 3. In order to purify water it should be either thoroughly filtered or boiled. 4. The solution prepared was sufficiently saturated to be used in this case. 5. The amount of the material was too small to be studied by the method in question. 6. The experiment was repeated so as to obtain more accurate results. 7. The analysis of the compounds of silicon and those of carbon has been made in order to establish the difference between them. 8. Crystalline silicon is hard enough to scratch glass. 9. The particles were so fine as to be invisible. 10. The work was such as to require a special equipment. 11. The substance was so volatile as to be collected only with great difficulty. 12. Mary Curie together with her husband Pierre Curie investigated pitchblende to discover an element of greater radioactivity than uranium itself. 13. Selenium and tellurium burn in air to form dioxides. 14. To produce penetrating rays from uranium compounds by any artificial means is not possible. 15. To produce artificial diamonds from carbon high pressure and high temperature are required.

II. Прочитайте и переведите следующие слова без словаря:

lithium /ÈlITI«m/, rubidium /ru:ÈbIdI«m/, periodic /ÇpI«rIȁdIk/, calcium /ÈkQlsI«m/, caesium /Èsi:zj«m/, amalgam /«ÈmQlg«m/, hydrolyze /ÈhaIdr«laIz/

III. Запомните чтение следующих слов:

toward /t«Èw:d/, usually /Èju:ZU«lI/, develop /dIÈvel«p/, slaked /ÈsleIkt/, benzene /Èbenzi:n/, benzine /Èbenzi:n/

Text 10 A

Alkali Metals

The elements of the Periodic Group I A, lithium, sodium, potassium, rubidium and caesium are called thealkali metals. These are alike in having a single electron in the outermost shell; since this electron is far removed from the rest of the atom, it is easily lost. Therefore, from the chemical point of view, these elements are the most active metals known. As we progress from lithium toward caesium, a striking increase in radius of the atom is to be observed.

Properties. Alkali metals have relatively low melting points and boiling points. They are soft enough to be easily cut with a knife, the softest being caesium. The latter is soft enough to be moulded¹ between fingers. They are also very light, the lightest being lithium, sodium and potassium. They are so light as to float on water.

The untarnished² surfaces of these metals may be seen to have a silvery lustre, but they rapidly tarnish and lose their lustre. The metals are usually stored in oil so as to exclude air. When stored in this way, they usually do not have a metallic appearance because of a surface coating.

The alkali metals are too active to be found free in nature. They are known to react with a number of non-metals, forming binary products, e. g. with chlorine to form chlorides, with bromine to form bromides and with sulphur to form sulphides.

The alkali metals are such active metals as to displace hydrogen from water, producing gaseous hydrogen and the hydroxide of the metal in solution. Potassium, rubidium and caesium develop enough heat in this reaction to ignite the liberated hydrogen.

2 Na + 2 H₂O = H₂ + 2 NaOH

They also displace hydrogen from acids, but the reaction is too violent to be of importance.

Reacting with oxygen, lithium yields the simple oxide, sodium, on the other hand, yields the peroxide unless the temperature is kept relatively low. When heated in air sodium and potassium readily take fire, each metal forming a mixture of oxides. The ordinary temperature is sufficient to ignite rubidium and caesium.

To prepare sodium hydroxide, a solution of sodium carbonate is added to slaked lime, calcium hydroxide, suspended in water. When exposed to air sodium hydroxide absorbs moisture and carbon dioxide, so it is used to remove both moisture and carbon dioxide from the air.

Примечания к тексту

1to mould – зд. разминать

2. untarnished – зд. свежесрезанный

Запомните следующие слова:

appearance, coating, displace, far, float, e. g. (= for example), lustre, outermost, slaked lime, shell, sufficient, tarnish, toward

Упражнения

I. Определите по характерным признакам функцию инфинитива в следующих предложениях и переведите предложения на русский язык:

1. To determine the volume of a gas at a definite temperature is rather easy. 2. To dissolve rubber, benzene or benzine are used. 3. Nitrogen peroxide is unstable enough to support ordinary combustion readily. 4. Gold and platinum do not gain weight when heated in air because they are too inactive to unite with oxygen. 5. Elementary lithium is too active to be of much use. 6. Tin is reactive enough to displace hydrogen from dilute acids but it does not tarnish in moist air. 7. A formula is used by chemists so as to represent the composition of one molecule of a substance. 8. To determine the molecular weight of a gas it is necessary to know its density in relation to hydrogen. 9. If two or more substances react to form a single substance, that substance is a compound. 10. Radium continuously emits heat at a rate sufficient to melt its own weight of ice every 45 minutes. 11. Metallic conductors do not appear to undergo any chemical change due to the passage of a current. 12. The examination of uranium minerals by M. Curie has shown some of them to emit radiations of greater intensity than uranium itself. 13. Investigation has shown radioactive changes to take place in series, the final non-radioactive product of these series being lead. 14. The so-called “amorphous carbon”, such as charcoal, appears upon examination by X-rays to resemble graphite in structure, except its being highly porous. 15. The grains a metal is made up may be so fine as to require a magnification of 100 times or more to reveal them.

II. Переведите следующие предложения на английский язык, пользуясь приведенной ниже рамкой:

1. Известно, что хлор – типичный неметалл. 2. Соединения щелочных металлов отличаются по своей промышленной важности. 3. Вода влияет на многие химические реакции. 4. Щелочные металлы хранятся в масле, чтобы исключить влияние воздуха. 5. Обычной температуры достаточно, чтобы воспламенить рубидий и цезий. 6. Гидроокись натрия используется, чтобы удалить из воздуха как влагу, так и двуокись углерода.

1. Water   2. Chlorine     3. Sodium hydroxide   4. The compounds of alkali metals 5. The alkali metals   6. The ordinary temperature

differ   is used     is known   influences   is sufficient   are stored

- to be a typical non-metal. - to remove both moisture and carbon dioxide from the air. - in their industrial importance. - in oil so as to exclude air. - many chemical reactions. - to ignite rubidium and caesium.

III. Дайте остальные основные формы следующих глаголов:

to lose, to see, to keep, to show

IV. Сгруппируйте синонимы и переведите их на русский язык:

alike, usually, to yield, generally, to manufacture, to give, similar, to produce

V. Сгруппируйте антонимы и переведите их на русский язык:

with difficulty, far, known, soft, near, easily, heavy, low, high, hard, light, unknown

VI. Укажите, к какой части речи относятся следующие слова, и переведите их на русский язык:

easily, metallic, reaction, rapidly, mixture, importance, moisture, active, relatively, chemical

VII. Переведите следующие предложения, обращая внимание на выделенные слова:

1. Diffusion in liquids takes place much more slowly than in gases. 2. Owing to its solubility hydrogen sulphide should not be collected over cold water. 3. Most of sulphur occurs in the earth’s crust as iron sulphide, but oxidation has given rise to large deposits of sulphate, chiefly of calcium and magnesium. 4. The reaction of magnesium with water occurs most rapidly if a small amount of some magnesium salt is present in water. 5. The total amount of radium produced up to 1940 amounted to about one kilogram. 6. Usually the most rapid and simplest chemical changes take place between dissolved substances. 7. Although the speed of a chemical reaction is modified by the presence of a catalyst, the final state of equilibrium is practically not affected. 8. The only gas giving red fumes when exposed to the air is nitric oxide.

VIII. Найдите в тексте эквиваленты следующих словосочетаний:

с химической точки зрения; самые активные из известных металлов; можно наблюдать поразительное увеличение радиуса атома; вследствие пленки на поверхности; при нагревании на воздухе

IX. а) Поставьте 6 вопросов к тексту;

б) Ответьте на следующие вопросы:

1. What elements are called alkali metals? 2. In what respects are the alkali metals alike? 3. What are the properties of the alkali metals? 4. Why are the alkali metals stored in oil? 5. Why are the alkali metals not found free in nature? 6. In what way is sodium hydroxide usually obtained?

X. Охарактеризуйте приведенные ниже высказывания, относящиеся к тексту 10 A, следующим образом: «правильно», «неправильно», «нет в тексте»:

1. Caesium is the most reactive member of the series of alkali metals. 2. Alkali metals are soft enough to be easily cut with a knife. 3. Alkali metals do not float on water. 4. Reacting with oxygen, lithium yields the simple oxide. 5. Sodium hydroxide is obtained by the electrolysis of common salt. 6. Alkali metals neither tarnish nor lose their lustre.

XI. Прочитайте текст 10 B, не пользуясь словарем:

TEXT 10 B