Век химии (Английский язык для студентов химического профиля). Учебное пособие

2. Write out.

а) key words and terms;

b) the sentences expressing the main idea of each paragraph

SUPPLEMENTARY TEXTS

Text 1

MODERN CHEMISTRY

Modern chemistry was slower to develop than astronomy and physics. It began in the 17th and 18th centuries when Joseph Priestley (1733-1804), who discovered oxygen in 1774, and Robert Boyle (1627-1691) began to record and publish the results of their experiments and to discuss their theories openly.

Boyle, who has been called the founder of modern chemistry, was one of the first to practice chemistry as a true science. He believed in the experimental method. In his most important book, “The Sceptical Chemist”, he clearly distinguished between an element and a compound or mixture. Boyle is the best known today for t h e gas law that bears his name.

A French chemist, Antoine Lavoisier (1743-1794), placed the science on a firm foundation wit h experiments in which he used a chemical balance to make quantitative measurements of the weights of substances involved in chemical reactions. The use of the chemical balance by Lavoisier and others later in the 18th century was almost as revolutionary in chemistr y as the use of the telescope had been in astronomy. Thereafter, chemistry became a quantitative experimental science. Lavoisier also contributed greatly to the organization of chemical data, to chemical nomenclature, and to the establishment of the law of conservation of mass in chemical changes.

During the period from 1803 to 1810, John Dalton (17661844), an English schoolteacher, advanced his atomic theory. This theory placed the atomistic concept of matter on a valid rational

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basis. It remains today as a tremendously important general concept of modern science. Since the time of Da lton, knowledge of chemistry has advanced in great strides, with the most rapid advancement occurring at the en d of the 19th century a n d during

fundamentals of life, developing chemical technology, and mass production of chemicals and related products.

Vocabulary List

to distinguish – различать, проводить различие; compound – соединение;

to bear one’s name – носить чьё-либо имя;

quantitative measurements – количественные измерения; to involve – вовлекать;

quantitative experiments science – количественная экспериментальная наука;

the law of conservation of mass – закон сохранения массы; great strides – большие успехи.

Text 2

BUTLEROV AND HIS THEORY OF CHEMICAL

STRUCTURE

A. M. Butlerov was born in 1828 in the town of Chistopol. In 1849 he graduated from the Kazan University, where he studied under the prominent Russian chemists K. Klaus and N. Zinin. After graduation Butlerov was left at the University and soon he began to deliver lectures in chemistry. For his prominent scientific merits Butlerov was elected a full member of the Russian Academy of Sciences.

From the very first steps of his scientific activities Butlerov showed himself to be a brilliant experimentor and carried out a number of remarkable syntheses.

Butlerov put forth a number of profound and daring ideas in the field of theoretical chemistry.

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The essence of Butlerov's theory consists in the statement that the properties of substances depend not only on their qualitative and quantitative composition, as was thought previously, but on their internal molecular structure as well, and on how the atoms, making up the molecule, are linked with each other. Butlerov, called this internal arrangement "chemical structure ". Butlerov's theory of chemical structure of molecules is the theoretical foundation of organic chemistry.

Vocabulary List scientific merits – научные заслуги; to be elected – быть избранным; daring ideas – смелые, дерзкие идеи; essence of smth. – суть чего-либо;

internal molecular structure – внутренняя молекулярная структура.

Text 3

THE STATES OF MATTER

That matter may exist in three physical states: solid, liquid or gas is a common knowledge. It is usually possible to change matter from one state to the other by changing its temperature. For instance, a piece of ice is called a solid; it may melt and form a liquid; as it evaporates, liquid water changes into a vapour, i.e. into the gaseous state.

Many kinds of matter, like water, can be obtained in each of the three states; for some, however, extraordinary means have to be used in order to produce one, or even two of the states; and for others, only two states are known or can be produced.

Common salt for example, exists normally as a solid; at a temperature of several hundred degrees, it can be liquefied; and at still higher temperature it is converted into vapour. Carbon, a solid under normal conditions, can be vaporized, but it has never been liquefied.

Solids have both a definite volume and a definite shape. Liquids too, have a definite volume, but they take the shape of their containers. Gases have neither a definite shape nor a definite volume. A chemist

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must have a thorough knowledge of the states of matter and of the physical laws which govern the behaviour of matter in various states.

That all matter is composed of molecules is known to everybody. The question which must be answered, then, is: if all matter is composed of molecules, what is the essential difference between the states of matter? The answer to this question is that the essential difference between these states is the relative quantities of energy molecules possess in different states.

Vocabulary List to exist – существовать;

solid – твёрдое состояние; liquid – жидкость;

to evaporate – выпаривать; to obtain – получать;

to be liquefied – быть превращённым в жидкость;

a chemist must have a thorough knowledge – химик должен хорошо знать.

Text 4

SUBSTANCES

Substances are distinguished by their properties – сolour, smell, taste, specific gravity, greater or lesser hardness, melting and boiling points, volatility, etc.

For example, in describing the properties of sugar, one can state that sugar is a hard, brittle substance, white in colour, sweet to the taste, without odour, easily soluble in water, heavier than water and it turns brown when it is heated, etc.

In order to learn the properties of a substance one must have it in its pure form. Even small admixtures of foreign substances may change the properties of a substance. For example: pure water is both colourless and transparent, but if a drop of milk is added to a glass of water, the water becomes clouded; if a drop of ink is added, the water becomes coloured. All the enumerated properties are not those of water but they are the properties of the admixtures.

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In some cases, one may see at once that a substance is heterogeneous, that is, a mixture of different substances.

Granite, cement, petroleum are examples of non-homogeneous materials; they consist of mixtures of substances. Thus, granite is a mixture of varying quantities of silica, feldspar, and mica, each of which possesses its own set of properties. Coal is not a substance too because different samples contain different relative amounts of ash, water, carbon, and other components.

Every material, therefore, consists of a single (pure) substance, or it is a mixture of two or more substances, each of which retains in the mixture its own characteristic properties.

Vocabulary List

smell – запах; taste – вкус;

melting and boiling points – точки плавления и кипения; volatility – летучесть, изменчивость;

brittle – хрупкий; odour – запах.

Text 5

CLASSIFICATION OF ORGANIC COMPOUNDS

In most of its compounds carbon exhibits a constant covalency of four. Probably owing again to its peculiar position in the Periodic Table the carbon atoms has the property of combining with other carbon atoms by means of one or more of its covalent linkages to from chains of atoms. Thus, one hydrogen atom of methane can be regarded as being replaced by a CH3 grop in ethane.

Similarly chains of three, four, five, etc. carbon atoms may be obtained producing propane, butane, pentane, and the higher hydrocarbons respectively. Compounds which contain straight chains of carbon atom are called aliphatic compounds. Introducing each carbon atom removes one hydrogen atom and replaces it by one carbon atom and three hydrogen atoms, the net increase being one atom of carbon and two of hydrogen. In this way a series of

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compounds is obtained, each number of which differs in formula from the member above or below it by a constant difference, namely CH2.

Such a series is called a homologue series. Every member of the series can be expressed by the general formula: CnH2n+2. The simplest homologue series begins with methane, CH4, and is as follows: methane, ethane, butane, pentane. In a large number of organic compounds the carbon atoms instead of being straight chains form closed rings containing six carbon atoms. Such substances are called aromatic compounds and if they contain in the ring atoms other than carbon, they are called heterocyclic, for example, pyridine.

The hydrocarbon methane with its four covalent linkages can not undergo chemical reactions to form a covalent compound except by removing one or more hydrogen atoms and their replacement by other atoms or groups A compound such as methane is called saturated. Compounds which can react merely by adding on other elements or groups of elements are called unsaturated and form addition products.

Vocabulary List

peculiar position – особое положение; covalent linkages – ковалентные связи; to replace – замещать;

to react –реагировать.

Text 6

SCOPE OF ENVIRONMENTAL ENGINEERING

Pollutants may be chemical, biological, thermal, radioactive, or even mechanical. Environmental engineering emphasizes several areas: process engineering, environmental chemistry, water and sewage treatment (sanitary engineering), waste reduction/management, and pollution prevention/cleanup. Environmental engineering is a synthesis of various disciplines, incorporating elements from the following:

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Environmental engineering is the application of science and engineering principles to the environment. Some consider environmental engineering to include the development of sustainable processes. There are several divisions of the field of environmental engineering.

Environmental impact assessment and mitigation.

In this division, engineers and scientists assess the impacts of a proposed project on environmental conditions. They apply scientific and engineering principles to evaluate if there are likely to be any adverse impacts to water quality, air quality, habitat quality, flora and fauna, agricultural capacity, traffic impacts, social impacts, ecological impacts, noise impacts, visual(landscape) impacts, etc. If impacts are expected, they then develop mitigation measures to limit or prevent such impacts. An example of a mitigation measure would be the creation of wetlands in a nearby location to mitigate the filling in of wetlands necessary for a road development if it is not possible to reroute the road.

Text 7

MODERN CHEMICAL ENGINEERING

The modern discipline of chemical engineering encompasses much more than just process engineering. Chemical engineers are now engaged in the development and production of a diverse range of products, as well as in commodity and specialty chemicals. These products include high performance materials needed for aerospace, automotive, biomedical, electronic, environmental and space and military applications. Examples include ultra-strong fibers, fabrics, dye-sensitized solar cells, adhesives and composites for vehicles, biocompatible materials for implants and prosthetics, gels for medical applications, pharmaceuticals, and films with special dielectric, optical or spectroscopic properties for opto-electronic devices. Additionally, chemical engineering is often intertwined with biology and biomedical engineering. Many chemical engineers work on biological projects such as understanding biopolymers (proteins) and mapping the human

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genome. The line between chemists and chemical engineers is growing ever more thin as more and more chemical engineers begin to start their own innovation using their knowledge of chemistry.

Text 8

REVERSE OSMOSIS

Reverse osmosis is a filtration process typically used for water. It works by using pressure to force a solution through a membrane, retaining the solute on one side and allowing the pure solvent to pass to the other side. This is the reverse of the normal osmosis process, which is the natural movement of solvent from an area of low solute concentration, through a membrane, to an area of high solute concentration when no external pressure is applied.

Procedure

Formally, reverse osmosis is the process of forcing a solvent from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure.

The membranes used for reverse osmosis have a dense barrier layer in the polymer matrix where most separation occurs. In most cases the membrane is designed to allow only water to pass through this dense layer while preventing the passage of solutes (such as salt ions). This process requires that a high pressure be exerted on the high concentration side of the membrane, usually 2–17 bar (30–250 psi) for fresh and brackish water, and 40–70 bar (600–1000 psi) for seawater, which has around 24 bar (350 psi) natural osmotic pressure which must be overcome.

This process is best known for its use in desalination (removing the salt from sea water to get fresh water), but it has also been used to purify fresh water for medical, industrial and domestic applications since the early 1970s.

When two solutions with different concentrations of a solute are mixed, the total amount of solutes in the two solutions will be equally distributed in the total amount of solvent from the two solutions.

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Instead of mixing the two solutions together, they can be put in two compartments where they are separated from each other by a semipermeable membrane. The semipermeable membrane does not allow the solutes to move from one compartment to the other, but allows the solvent to move. Since equilibrium cannot be achieved by the movement of solutes from the compartment with high solute concentration to the one with low solute concentration, it is instead achieved by the movement of the solvent from areas of low solute concentration to areas of high solute concentration. When the solvent moves away from low concentration areas, it causes these areas to become more concentrated. On the other side, when the solvent moves into areas of high concentration, solute concentration will decrease. This process is termed osmosis. The tendency for solvent to flow through the membrane can be expressed as "osmotic pressure", since it is analogous to flow caused by a pressure differential.

In reverse osmosis, in a similar setup as that in osmosis, pressure is applied to the compartment with high concentration. In this case, there are two forces influencing the movement of water: the pressure caused by the difference in solute concentration between the two compartments (the osmotic pressure) and the externally applied pressure.

Text 9

A MEMBRANE REACTOR

A membrane reactor is a piece of chemical equipment that combines a catalyst-filled reaction chamber with a membrane to add reactants or remove products of the reaction.

Chemical reactors making use of membranes are usually referred to as membrane reactors. The membrane can be used for different tasks:

Separation

Selective extraction of reactants Retention of the catalyst Distribution/dosing of a reactant

Catalyst support (often combined with distribution of reactants)

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Membrane reactors are an example for the combination of two unit operation in one step e.g. membrane filtration with the chemical reaction.

In biological systems membranes fulfil a number of essential functions. The compartmentalisation of biological cells is achieved by membranes. The semi-permeability allows to separate reactions and reaction environments. A number of enzymes are membrane bound and often mass transport through the membrane is active rather than passive as in artificial membranes allowing the cell to keep up gradients for example by using active transport of protons or water.

The use of a natural membrane is the first example of the utilization for a chemical reaction. By using the selective permeability of a pigs bladder water could be removed from a condensation reaction to shift the equilibrium position of the reaction towards the condensation products according to the principle of Le Châtelier.

Continuous oscillatory baffled reactor (COBR) is a tubular plug flow reactor. The mixing in COBR is achieved by the combination of fluid oscillation and orifice baffles, allowing plug flow to be achieved under laminar flow conditions with the net flow Reynolds number just about 100.

Semi-batch reactor

A semi-batch reactor is operated with both continuous and batch inputs and outputs. A fermenter, for example, is loaded with a batch, which constantly produces carbon dioxide, which has to be removed continuously. Analogously, driving a reaction of gas with a liquid is usually difficult, since the gas bubbles off. Therefore, a continuous feed of gas is injected into the batch of a liquid. An example of such a reaction is chlorination.

Catalytic reactor

Although catalytic reactors are often implemented as plug flow reactors, their analysis requires more complicated treatment. The rate of a catalytic reaction is proportional to the amount of catalyst the reagents contact. With a solid phase catalyst and fluid phase reagents, this is proportional to the exposed area, efficiency of diffusion of reagents in and products out, and turbulent mixing or lack thereof. Perfect mixing cannot be assumed. Furthermore, a catalytic reaction pathway is often multi-step with intermediates that are chemically

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