3. Homogeneous material is material with the same properties throughout.
4. Heterogeneous material is material consisting of parts with different properties.
5. Compound is a substance that can be decomposed into two or more substances.
6. Substance is a homogeneous species of matter with definite chemical
composition.
7. Chemical reactions are the processes that convert substances into other
substances.
8. Alloy is a metallic material containing two or more elements.
Common examples of substances are: water, sugar, salt, copper, iron and many others. Chemists study substances in order to learn as much as they can about their properties and about the reactions that change them into other substances. This knowledge is very important as it can make the world a better place to live in, it can make people happier, it can raise their standard of living.
Chemists discovered many laws, investigated many important phenomena in life. They produced many artificial substances which have valuable properties.
Chemistry has two main aspects: descriptive chemistry, the discovery of chemical facts, and theoretical chemistry the formulation of theories.
The broad field of chemistry may also be divided in other ways. An important division of chemistry is that into the branches of organic chemistry and inorganic chemistry.
Organic chemistry is the chemistry of the compounds of carbon that occur in plants and animals.
Inorganic chemistry is the chemistry of the compounds of elements other than carbon. Each of these branches of chemistry is in part descriptive and in part theoretical.
Analytical chemistry deals with the methods of separation. Synthetic chemistry deals with the methods by which complex bodies can be built from simpler substances. Physical chemistry deals with changes of state and with the motions of molecules. But at present the scientists don't maintain this definition.
Questions on the text:
1) What does chemistry study? 2) What is chemistry concerned with? 3) What does chemical industry make it possible to create? 4) What should we remember? 5) Give common example of substances 6) Why do chemists study substances? 7) What are two main aspects of chemistry? 8) What does organic chemistry study? 9) What does inorganic chemistry deal with? 10) What other fields of chemistry are mentioned (упоминаются) in the text?
№ 9. MEASUREMENTS IN CHEMISTRY
Words to be remembered:
quantity – количество
quantitative relationship – количественная связь
various – различный, разнообразный
to undergo changes – претерпевать изменения, подвергаться изменениям
since – так как
to measure – измерять
measure – мера
measurement – измерение
measuring device – измерительное устройство
to take into account – принимать во внимание, учитывать
to employ – применять, использовать
volume – объем
sample – образец
to permit – позволять, разрешать
object – объект, предмет, тело
In order to understand the quantitative relationships which exist between various kinds of matter, the chemist who is interested in matter and changes which
it undergoes, has to measure the quantities of matter with which he works. Since mass is the measure of the quantity of matter, he is to measure mass. The measuring device the chemist is to employ in this determination should be the balance.
Since for every chemical change there is always accompanying energy change which the chemist has to take into account, the calorimeter and the thermometer have to be used.
The chemist usually employs graduated cylinders, burettes, pipettes and volumetric flasks for the measurements of volumes of liquids, and the gas burette for the measurement of volumes of gases.
The chemist employs the barometer if he has to measure the pressure.
The analytical chemist and the physical chemist employ such devices as calorimeters, refractometers, and a number of electrical devices.
If the chemist is to examine very small samples of matter, he should use a microscope. The microscope is an instrument which by the combination of lenses permits man to see objects which are too small to be seen with a naked eye; it is an instrument which is useful in many sciences and which, although more frequently used in a qualitative way, can also be used quantitavely.
Questions on the text:
1) What should we do in order to understand the quantitative relationships between various kinds of matter? 2) What is the chemist interested in? 3) What does mass show? 4) What measuring device does the chemist use to measure mass? 5) What other devices does the chemist employ? 6) What is measured with the barometer? 7) What kind of device is a microscope? 8) Is a microscope useful only in chemistry?
№ 10. CARBON
Words to be remembered:
carbon – углерод
to occur – залегать, встречаться
lubricant – смазка
to burn – гореть, сгорать
carbon monoxide (CO) – окись углерода, угарный газ
carbon dioxide (CO2) – двуокись углерода, углекислый газ
the former … the latter – первый … последний (из упомянутых)
to produce – (зд.) вырабатывать, производить; образовываться
deficiency – недостаток
oxygen – кислород
to result in – приводить к чему-либо
colourless – бесцветный
odourless – без запаха
soluble – растворимый
solubility – растворимость
to dissolve – растворять
reducing agent – восстановитель, регенератор
acid – кислота; кислый
due to – из-за
carbonic acid – угольная кислота
vapour pressure – паровое давление, давление пара
to vaporize – испаряться
Carbon occurs in nature in its elementary state in two allotropic forms namely diamond, this being the hardest substance known, and graphite, a soft, black crystalline substance used as a lubricant. Having investigated all the substances thoroughly the scientists found charcoal, coke, and carbon black to be microcrystalline or amorphous ( non-crystalline ) forms of carbon.
Carbon burns to form gases: carbon monoxide, and carbon dioxide, the former is produced when there is a deficiency of oxygen or the flame temperature is very high.
This investigation followed by others resulted in new discoveries in the field of carbon. It has been found out that carbon monoxide is a colourless, odourless gas with small solubility in water. It is poisonous because of its ability to combine the hemoglobin in the blood in the same way that oxygen does, and thus to prevent the hemoglobin from combining with oxygen in the lungs and carrying it to the tissues. It should be noted that the exhaust gas from automobile engines contain some carbon. Nevertheless carbon monoxide is a valuable industrial gas, for use as a fuel and as a reducing agent.
Carbon dioxide is a colourless, odourless gas with a weakly acid taste, due to the formation of some carbonic acid when it is dissolved in water. It appears to be about 50% heavier than air. It is easily soluble in water, one liter of water at 0°C dissolving 1,713 ml of gas under 1 atm pressure.
When crystalline carbon dioxide is heated from a very low temperature its vapour pressure reaches 1 atm at 79° at which temperature it vaporizes without melting. If pressure were increased to 2,5 atm the crystalline substance could be changed directly to a gas.
Carbon dioxide is known to combine with water to form carbonic acid. If you studied all the properties more thoroughly you would see that carbon dioxide is used for the manufacture of sodium carbonate, sodium hydrogen carbonate, and carbonated water and for many other uses.
From this short review it’s clear that chemistry of carbon and its compounds is a very important field of chemistry and should be studied carefully.
Questions on the text:
1) In what two forms does carbon occur in nature? 2) What are microcrystalline or amorphous forms of carbon? 3) What gases can carbon form when burning? 4) How is carbon monoxide produced? 5) What is carbon monoxide? 6) Why is it poisonous? 7) Is it a valuable industrial gas? 8) What can you say about carbon dioxide? 9) What does the combination of water and carbon dioxide form? 10) How is carbon dioxide used?
№ 11. HYDROGEN
Words to be remembered:
hydrogen – водород
light – легкий
density – плотность
i.e. = id est = that is – то есть
in free state – в свободном виде
because of – из-за
reserves – резервы, запасы
energy source – источник энергии
environment – окружающая среда, экология
to transport by pipelines – перекачивать по трубопроводам
to transmit electricity – передавать электричество
to accumulate – накапливать
either … or – или … или, либо … либо
to obtain – получать
Hydrogen is known to be the lightest of the elements. If the temperature is 20°C, it is an odourless, colourless, tasteless gas, its density being 0.08987, i.e. 1/15 that of air.
The gas is only slightly soluble in water, its solubility under standard pressure in 100 ml of water being 1,93 ml at 0°C.
Hydrogen could be found in the free state only in minute quantities because of its marked chemical activity. Specialists consider hydrogen to be an extremely promising energy source. The reserves of hydrogen are known to be practically unlimited. Another plus is that hydrogen can be used as fuel in transport, industry and at home. Extensive use of hydrogen as an energy source will help keep the environment clean.
Hydrogen is easy to transport and store. Even today, it costs several times less to transport by pipelines than to transmit electricity. Like any other gaseous fuel it could be accumulated and kept for a long time either in conventional or natural reservoirs.
Scientists have found many ways of producing hydrogen - basically from ordinary water, large volumes of this fuel could be obtained from coal, its reserves being tremendous.
Questions on the text:
1) What is the lightest element? 2) What are the properties(свойства) of hydrogen at 20°C? 3) Why can we find hydrogen in the free state only in minute quantities? 4) What can you say about the reserves of hydrogen? 5) Where can it be used as a fuel? 6) Is it easy to transport and store hydrogen?
№12. FUEL
Words to be remembered:
constituent – составляющая, составляющая часть
solid fuels – твердые виды топлива
coal – уголь
decomposition – разложение, распад
vegetable matter – растительное вещество
to consist of – состоять из
volatile matter – летучее вещество
anthracite coal – антрацит
bituminous coal – битуминозный уголь
to convert – превращать
coke – кокс
to heat – нагревать
coke oven – коксовая печь
to distill – дистиллировать, очищать
petroleum – нефть
coal gas – каменноугольный газ
methane – метан
illuminating gas – светильный газ
natural gas – природный газ
well – скважина
largely – в основном
Carbon and hydrogen are the principal constituents of the solid fuels, coal and wood. Coal has been formed in nature by the slow decomposition of vegetable matter, in the presence of water and absence of air. Most of it was formed during the Carboniferous Period of geologic time, about 250 million years ago. Coal consists of free carbon mixed with various carbon compounds and some mineral matter. Anthracite coal (hard coal) contains much volatile matter, and burns with a smoky flame.
Bituminous coal can be converted into coke by heating without access of air. When the heating is carried out in a coke oven, many substances distill out, including gas for fuel, ammonia, and a complex mixture of liquid and solid organic compounds. The solid material remaining in the oven, consisting mainly of carbon, is called coke, it burns with a nearly colorless flame, and is used in great amounts in metallurgical processes.
Petroleum is a very important liquid fuel. It is a complex mixture of compounds of carbon and hydrogen.
The gas obtained from a coke furnace (coal gas) consists of hydrogen (about 30%), methane, carbon monoxide (10%) and minor components. This coal gas was the original illuminating gas.
Natural gas, from gas wells and oil wells, consists largely of methane.
Questions on the text:
1) What are the principal constituents of the solid fuels? 2) How is coal formed? 3) When was most of it formed? 4) What does coal consist of? 5) What is anthracite coal? 6) How can bituminous coal be converted into coke? 7) What substances distill out in a coke oven? 8) What solid material remains in the oven? 9) What is petroleum? 10) What does the gas obtained from a coke furnace consist of ? 11) What is the main component of natural gas?
PART II
Translate the following texts using a dictionary:
UNIT 1 OIL
Words to be remembered:
vegetable remains – растительные остатки
hydrocarbon - углеводород
complexity - сложность
infinite number – бесконечное количество
to distinguish - различаться
property - свойство
to determine - определять
ceresine - церезин
sulphur -сера
nitrogen - азот
crude oil – сырая нефть
wax - воск
solution - раствор
release of pressure – (pl/) понижение давления
refining – переработка (нефти), очистка
to recover - добывать
gas cap – газовая шапка
smell=odour - запах
quantity - количество
impurity - примесь
specific gravity – удельный вес
to dissolve - растворяться
combustible - горючий
All over the world there are accumulations of hydrocarbons formed long ago by decomposition of animal and vegetable remains. Hydrocarbons are compounds of hydrogen (11-14%) and carbon (84-86%) that, at normal temperatures and pressure, may be gaseous, liquid or solid. There is an infinite number of hydrocarbons; they are all distinguished by their internal structure, carbon-hydrogen proportion and, therefore, by their chemical and physical properties.
The oil of most oil fields consists of methane and saturated hydrocarbons. The molecules of methane hydrocarbons are a chain of atoms of carbon with atoms of hydrogen added. Their structure is determined by the formula CnH2n+2, where n shows the number of atoms in a molecule beginning with one.
Hydrocarbons with a small number of carbon atoms from CH4 to C4H10 are gases under standard conditions (a pressure of 760 mm of mercury and a temperature of +20 degrees Centigrade). Heavier hydrocarbons, from C5H12 to C16H34, are liquids under these conditions. Methane hydrocarbons with a still greater content are solids called paraffines and ceresines.
Oil also has smaller quantities of sulphur, oxygen and nitrogen.
Most crude oils, although liquid as such, contain gaseous and solid hydrocarbons in solution. The gases come out of solution either on the release of pressure as the crude oil is or during the first stages of refining. Some of the solids are recovered during refining as bitumen and wax. Natural gas is also found associated with crude oil as a gas cap above the oil or unassociated with oil.
Petroleum is a substance with a characteristic smell. The odour of petroleum depends on the nature, composition and quantity of hydrocarbons and different impurities. Its colour varies from light brown to dark brown, nearly black. Specific gravity of oil determines its colour. The heavier the oil the darker is the colour. Oil is much lighter than water. It doesn’t dissolve in water and forms a thin rainbow film on its surface. All sorts of oil are combustible.
Questions on the text:
1) What are hydrocarbons? 2) How were they formed? 3) How are hydrocarbons distinguished? 4) What formula determines the structure of methane hydrocarbons? 5) Do most oils contain gaseous or solid hydrocarbons in solution? 6) When do gases come out of solution? 7) What happens during the first stages of refining? 8) What is called a gas cap? 9) What does the odour of petroleum depend on? 10) What determines its colour? 11) What is the dependence of the colour of oil on its specific gravity? 12) Is water lighter or heavier than oil? 13) Are all sorts of oil combustible?