Physical and Chemical Properties of Substances

Properties.Bodies are composed of materials such as wood, steel, cement, stone, silver, gold, lead, iron, etc. These materials may be either homogeneous or heterogeneous. A substance is defined¹ as a variety of matter which has definite properties and definite composition. All samples of a substance possess the same properties and have the same composition, regardless of their source². Every substance therefore possesses specific physical properties, such as colour, odour, density, hardness, melting point, and boiling point.

Every substance also possesses definite chemical properties; these concern its transformations³ into other substances, and especially, the different kinds of substances into which it can be transformed. Water is an example of a substance; one sample of water is like all others and there is only one set of properties by which all samples of water can be described and identified.

Примечания к тексту

1. define –определять

2. regardless of their source –независимо от их источника

3. these concern its transformations –они связаны с его превращением

XII.Поставьте три вопроса к каждому абзацу текста и передайте содержание прочитанного на английском языке.

XIII.Переведите на английский язык, пользуясь словами и словосочетаниями из предыдущих текстов:

Химия изучает вещества, их состав, а также процессы и законы, по которым происходит изменение их состава. Все окружающие нас предметы состоят из веществ. Вещества состоят из одинаковых молекул и различаются по своим свойствам. Свойства веществ можно разделить на две группы: физические и химические. При изменении физических свойств состав вещества не меняется. Изменение химических свойств веществ связано с изменением их состава.

LESSON 6

Грамматика. Дополнительные придаточные предложения. Различные значения that.

Предтекстовые упражнения

I.Укажите,какими союзами и союзными словами вводятся придаточные дополнительные предложения, и переведите следующие предложения на русский язык:

1. By means of this formula one can easily determine whether a given gas is lighter or heavier than air. 2. One can show experimentally that hydrogen does not support burning. 3. At the beginning of the experiment it is not known yet if the necessary data will be obtained. 4. Everybody knows how closely chemistry is connected with the progress of the world. 5. The students want to know who will deliver lectures on chemistry. 6. Newton first explained why all objects on the Earth attracted one another.

II.Найдите придаточные предложения и переведите их на русский язык:

1. The students told their teacher they were ready to start their work. 2. The newcomer said he had come from the Far East. 3. We didn’t know you could speak German. 4. My friend thinks he can finish his work in an hour.

III.Определите значения слова that и переведите следующие предложения на русский язык:

1. Now we know that all substances consist of atoms. 2. It was in Russia that the large-scale production of synthetic rubber was established. 3. That water is a compound was proved at the end of the 18^th century. 4. The decision of the commission was that the discovery was of great importance to industry. 5. The distance that light travels in one second is 300 thousand kilometers. 6. The melting point of titanium is 2,000⁰ above that of aluminium. 7. The properties of metals are different from those of wood.

IV.Переведите следующие слова, не пользуясь словарем:

barometer [bə'rmɪtə], character ['kærɪktə], condensation [ˌknden'seɪʃən], formula ['fɔ:mjUlə], fundamental [ˌfʌndə'mentl], information [ˌɪnfə'meɪʃn], platinum ['plætɪnəm], progress ['pr«Ugres]

V.Переведите предложения, обращая внимание на значение следующих слов и словосочетаний:

effect n – действие; влияние; результат

1. The effect of heat influences the rate of many reactions. 2. Scientists study the effect of cosmic radiation upon the human body. 3. The effect of our experiment was excellent.

effect v – производить; выполнять; осуществлять

1. They effected a change in the plan of their work. 2. The scientists effected the plan of their research before the time appointed. 3. They effected the isolation of a new substance.

to affect v – воздействовать на

Moisture affects many metals.

it takes – нужно, требуется

It takesenergy to move a body.

to mean – значить, означать

Isotopes are different forms of the same element (simple type of a substance). The word “isotope” means “same place”.

means n – средство; средства

1. Atoms cannot be broken down by chemical means, so it’s impossible to break up an element into simpler substances by chemical changes. 2. At present we have many meansof defense against air and chemical danger.

by means of – посредством

One can express the composition of a compound by means of a chemical formula.

VI.Обратите внимание на ударение в следующих словах. Переведите эти слова:

'element – ele'mentary, 'atom – a'tomic, 'molecule – mo'lecular, 'oxidize – oxi'dation, re'duce – re'duction, e'lectric – elec'tricity, 'metal – me'tallic, 'stable – sta'bility, 'compound – com'pound, 'transport – trans'port

VII.Запомните произношение следующих слов:

necessary ['nesɪsərɪ], acquainted [ə'kweɪntɪd], essential [«'senʃ«l], lustrous ['lʌstrəs]

TEXT 6 A

Changes of Matter

None of the properties of a substance is more important to the chemist than the changes the substance can undergo, and no knowledge about the substance is more important than information concerning the conditions that are necessary to effect these changes. We know of many changes that occur continually around us and that alter greatly the different forms of matter we are acquainted with. These changes are either physical or chemical.

Chemical Changes

Chemical changes are those matter changes in which a change of composition takes place. Such changes are permanent, i.e. they cannot be undone¹ by simple application of some physical means, such as heating, cooling, or evaporation, but the new substance, or substances formed persist² unless they are subjected to another chemical change. In determining whether a given matter change is a physical or chemical change, the essential question is whether or not one or more substances, with properties different from those of the substance or substances existing before the change, have been formed.

Thus iron is a hard, grayish, lustrous substance but when it is left exposed to moist air it is slowly transformed into a red crumble material (iron rust) quite different in properties from the original iron.

A chemical change has, therefore, taken place; the change in properties is the outward indication of the formation of a different substance. The new, reddish substance will not become iron again when it is allowed to stand, although the iron can be obtained from it, if it is subjected to the right conditions. It took a chemical change to convert iron into iron rust, and another chemical change would be necessary³ to turn the iron rust into iron again.

In the burning of wood a chemical change takes place, since the wood disappears and new substances (gases, ash, etc.) appear which are very different in their properties from wood.

Примечания к тексту

1. they cannot be undone –они не могут быть уничтожены

2. substances formed persist –образовавшиеся вещества сохраняются

3. and another chemical change would be necessary –и потребовалось бы другое химическое изменение

Запомните следующие слова и словосочетания:

after, appear, around, cooling, effect, essential, gray, greatly, hard, heating, indication, i.e., lustrous, moist, occur, outward, permanent, subject to, transform, undergo, wood

Упражнения

I.Выпишите из текста: а) дополнительные придаточные предложения; б) предложения, в которых встречается that, и определите его значения; в) бессоюзные определительные придаточные предложения.

II.Поставьте вопросы к выделенным словам:

1.When iron is exposed to moist airit is slowly transformedinto iron rust.2.In the burning of wood a chemical changetakes place. 3. During the burning wood disappearsandnew substancesappear.

III.Переведите следующие предложения на русский язык, обращая внимание на значениеthat:

1. Some properties of air are similar to those of water. 2. We know that air has pressure. 3. A barometer is an instrument that measures air pressure. 4. The production of ozone requires that a large quantity of energy be absorbed. 5. It is the law of conservation of mass that makes possible the writing of chemical equation. 6. The amount of heat liberated by slow oxidation is the same as that liberated by rapid combustion. 7. That water is a compound was proved at the end of the 18^th century.

IV.Определите по суффиксам, к какой части речи относятся данные слова, и переведите их на русский язык:

property, substance, chemist, information, important, necessary, continually, chemical, composition, different, essential, grayish, lustrous

V.Переведите следующие слова, обращая внимание на суффикс -ish:

reddish, bluish, yellowish, grayish

VI.Сгруппируйте синонимы и переведите их на русский язык:

important, moist, to permit, to occur, right, to alter, to convert, essential, to change, since, to allow, to take place, because, wet, proper

VII.Сгруппируйте антонимы и переведите их на русский язык:

necessary, to disappear, greatly, similar, heating, moist, slowly, to allow, right, to appear, to prohibit, rapidly, dry, cooling, to a little extent, different, wrong, unnecessary

VIII.Дайте недостающие основные формы следующих глаголов:

to undergo, to take, to give, to leave, to become

IX.Заполните пропуски следующими словами и словосочетаниями:

to turn, takes place, whether, unless, in time, to subject, to take

1. Chemical changes are those matter changes in which a change of composition … . 2. It is essential … you finish your experiment … . 3. This substance will not change its properties … you … it to a chemical change. 4. It … a chemical change to convert iron into iron rust. 5. A chemical change is necessary ... the iron rust into iron again.

X.Ответьте на следующие вопросы:

1. What changes of matter do we call chemical changes? 2. What is the essential question in determining whether a matter change is a physical or a chemical one? 3. What are the properties of iron? 4. What happens if iron is left exposed to moist air? 5. Why do we say that in the burning of wood a chemical change takes place?

XI.Выберите правильный английский вариант перевода:

1.	означать	а)	by means of
2.	превращаться в ржавчину	б)	necessary
3.	изменяться	в)	to turn into rust
4.	осуществлять, производить	г)	rust
5.	иметь место	д)	it took a chemical change
6.	посредством	е)	although
7.	если … не	ж)	to allow
8.	необходимый	з)	outward
9.	применение	и)	to determine
10.	подвергать действию	к)	to subject to
11.	определять	л)	application
12.	внешний	м)	unless
13.	позволять	н)	to take place
14.	хотя	о)	to effect
15.	потребовалось химическое изменение	п)	to mean
16.	ржавчина	р)	to alter

XII.Прочитайте текст 6 В, не пользуясь словарем:

TEXT 6 B

Physical changes

When physical changes occur, some of the properties of a substance may be altered for a time, but no new substances are formed. The following are the examples of a physical change: 1) the melting of ice and the condensation of steam; 2) the mixing of sugar with water to form a solution; 3) the change observed when a platinum wire¹ is heated to redness. In each of these there is a change in properties.

Thus, a liquid is produced from a solid when ice melts, and a gas is changed into a liquid when steam condenses.

When sugar dissolves, it, too, changes from the solid to the liquid state.

The platinum wire changes, when heated², from a silvery lustrous metal that reflects light to one that emits³ light. But there is no alternation of the fundamental character of any of the substances during these changes.

Sugar dissolved in water retains⁴ its original properties and only forms a mixture from which it is readily obtained again in its crystalline form by allowing the water to evaporate.

Примечания к тексту

1. wire [waɪə(r)]–проволока

2. when heated – при нагревании

3. emit [ɪ'mɪt]–испускать

4. retain[rɪ'teɪn]–сохранять

XIII.Поставьте три вопроса к каждому абзацу текста.

XIV.Переведите, пользуясь словами и словосочетаниями из текстов А и В:

Плавление, кипение веществ, изменение их формы, нагревание или охлаждение – все эти явления (phenomena) называются физическими. В результате физических изменений состав вещества не меняется.

Такие изменения веществ, в результате которых из одних веществ получаются другие, называются химическими явлениями или химическими реакциями.

В природе химические реакции иногда протекают весьма медленно, поэтому мы их не всегда замечаем.

XV.Расскажите на английском языке, в чем заключается разница между физическими и химическими изменениями.

LESSON 7

Грамматика. Условные предложения.

Предтекстовые упражнения

I.Определите тип условного предложения в следующих сложных предложениях и переведите их на русский язык:

1. If a substance cannot be decomposed or produced by combination of other substances, it is called an element. 2. If a gas were colourless, we would not notice its formation. 3. We should have obtained better results if we had used some other materials. 4. Unless the achievements of the scientists of our research Institute had been so great, many of the complex problems would not have been solved. 5. If a substance changes from one state into another, its energy content will change too. 6. If a substance passed from the solid state directly to the vapour state, this change would be called sublimation. 7. You will see a great variety of apparatus if you visit some laboratory. 8. The liquid in the test-tube would change its colour if they raised the temperature. 9. They would have measured the weight of a substance more accurately provided they had taken an analytical balance.

II.Прочитайте и переведите следующие предложения, обращая внимание на выделенные слова:

due to – благодаря

Due toRussian scientist D. I. Mendeleyev elements have been arranged in the order of their atomic weights.

be due to – объясняться, обуславливаться

The change of colour is due to heating.

slightly – слегка

The colour of this liquid changes slightly on heating.

III.Прочитайте и переведите следующие слова, не пользуясь словарем:

component [kəmˈpəUnənt], gas [gæs], distillation [ˌdɪstɪˈleɪʃ(ə)n], analyse [ˈænəlaɪz], temperature [ˈtemprItʃə], proportion [prəˈpɔːʃ(ə)n], apparatus [ˌæpəˈreɪtəs], nitrate [ˈnaɪtreɪt], barium peroxide [ˈbɛərɪəm pəˈrɒksaɪd]

IV.Запомните чтение следующих слов:

air [ɛə], nitrogen [ˈnaɪtrIdʒən], physical [ˈfɪzɪkl], occur [əˈkÎ:], infer [ɪnˈfÎ:], vary [ˈvɛərɪ], precisely [prɪˈsaɪslɪ]

Text 7 A

Air

One can prove in several ways that air is not a chemical compound, but a mixture of nitrogen and oxygen with small amounts of other gases.

The composition of air varies slightly with elevation, being a little¹ richer in oxygen and poorer in nitrogen at sea level than at elevations of a few miles. If it were a single² compound, it would have a definite composition by weight.

Air is readily separated into its components by fractional distillation of liquid air. If it were a compound, it would all distil over in a single fraction³ at a definite temperature.

The air that surrounds us is about one fifth oxygen by volume. When cold water is slowly warmed, we see bubbles of “dissolved air” coming out of the solution. If we analyse such bubbles, we shall find that they are about one third oxygen by volume. The change in composition is due to the difference in the solubility of the gases that make up the mixture known as air. If air were a single compound, the bubbles that escape from the solution would have the same composition as those of the undissolved air.

The density and physical properties of air are precisely those that would be inferred from the proportions and physical properties of its component gases. If a chemical change occurred in mixing these gases to form air, there would be either a change in properties or a change in volume.

No chemical formula can be written that would exactly show the proportions in which nitrogen and oxygen are present in air. The nearest simple formula would be N₄O, but this would indicate far too great a density4 for air, and the proportion of oxygen in air is slightly greater than this formula indicates.

Примечания к тексту

1. a little– немного

2. single– зд. простой

3. distil over in a single fraction– перегоняются в одну фракцию

4. far too great a density –слишком большая плотность

Запомните следующие слова и словосочетания:

air, be due to, bubble, component, density, either … or, elevation, exactly, if, in several ways, make up, mix, occur, poor, precisely, prove, readily, (the) same, sea level, slightly, slowly, solubility, weight

Упражнения

I.Определите тип условного предложения в следующих сложных предложениях и переведите их на русский язык:

1. If water had been poured into concentrated sulphuric acid, an explosion would have occurred. 2. If an aqueous solution of chlorine yellow in colour is exposed to light, the yellow colour will gradually disappear. 3. The volume the gas would occupy provided it were dry, is less than that which it occupies when water vapour is present. 4. The study of any substance would be incomplete unless we investigated the properties of that substance and the methods of obtaining its components. 5. If a solution of barium peroxide in water were concentrated by boiling, the hydrogen peroxide would be decomposed by heating. 6. The gas would have occupied much smaller volume if it had been compressed enough. 7. If the oxides of antimony were even moderately basic in character, they would react with nitric acid to form the nitrate of antimony. 8. The low density of ice is an important property, for our climate would certainly be quite different unless ice floated. 9. If ozone were suddenly withdrawn from the atmosphere, we should all be killed within a few minutes by the sun’s ultra-violet light. 10. If petroleum suddenly disappeared, we would find ourselves without any gasoline for our machines.

II.Выпишите из текста условные предложения II типа, переведите их на русский язык.

III.Закончите следующие предложения, пользуясь русским текстом:

1. If we analysed the bubbles of dissolved air, (мы бы увидели, что они по объему состоят на 1/3 из кислорода). 2. If we wrote the formula N₄O for air, (она не показала бы точных соотношений, в которых кислород и азот присутствуют в воздухе). 3. If the composition of air were analysed at sea level, (можно было бы видеть, что он немного богаче кислородом и беднее азотом, чем на высоте в несколько миль). 4. If we separated air into its components, (мы бы получили кислород, азот и небольшое количество других газов).

IV.Выпишите из текста существительные, соответствующие следующим глаголам, подчеркните их суффиксы и переведите их на русский язык:

distil, differ, compose, dissolve, elevate, mix

V.Дайте антонимы к следующим словам:

cold, large, rich, different, absent, complex, far

VI.Заполните пропуски данными словами или словосочетаниями:

components, amounts, to separate, escape, mixture, chemical compound, bubbles, density

1. We know that air is not a … . 2. When water boils we see … of “dissolved air” … from the solution. 3. Air is a … of nitrogen and oxygen with small … of other gases. 4. Fractional distillation is used … air into its … . 5. The formula N₄O indicates far too great a … for air.

VII.Найдите в тексте эквиваленты следующих словосочетаний:

несколькими способами, дробная перегонка, примерно на одну пятую, никакая химическая формула, слишком большая плотность

VIII.Переведите на русский язык, обращая внимание на выделенные слова:

1.Due toits greater energy content ozone is more reactive than oxygen. 2. Oxygen is slightlydenser than air and slightlysoluble in water. 3. The bleaching effects of sulphurous acid are due toits reducing properties. 4. The composition of water varies slightlywith elevation. 5. The energies due toVan der Vaals’ forces seldom exceed a few Kcal/mole.

IX.Ответьте на следующие вопросы:

1. What is air? 2. Under what conditions is air richer in oxygen and poorer in nitrogen? 3. In what way is air separated into its components? 4. How much oxygen does air generally contain?

X.Прочитайте текст 7 В, не пользуясь словарем:

Text 7 B