Добавил:
ivanov666
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Polimers. Учебное пособие по подготовке к интернет-экзамену по английскому языку
.pdf
ФЕДЕРАЛЬНОЕ АГЕНТСТВО ПО ОБРАЗОВАНИЮ
Государственное образовательное учреждение высшего
профессионального
образования
Казанский государственный технологический университет
POLIMERS
особие для подготовки к Интернет-экзамену)
(П
Английский язык
азань
К
КГТУ
2011
УДК 802 (075).66
ББК43.6.2.15
Арефьева, Ф.Г.
POL
IMERS. учебное пособие по подготовке к интернетэкзамену по английскому языку / Ф.Г. Арефьева. – Казань
:Казан. гос.технолог.ун-т; Казань 33 стр.
2011. - 1
Пособие соответствует государственному
образовательному стандарту дисциплины «Иностранный язык»
В пособие включены следующие разделы:тексты по
специальности 240502 «Технология переработки
пластических масс и эластомеров», 240501 «Химиическая технология высокомолекулярных соединений»,
грамматический материал, некоторые сведения о странах
изучаемого языка, деловая корреспонденция, а так же тесты
по специальностям, взятые из Интернет-экзамена.
Грамматический материал представлен в виде таблиц, что
облегчает восприятие материала.
Данное учебное пособие предназначено для
подготовки к Интернет – экзамену по английскому языку
студентов 2-3 курсов полимерного факультета. Подготовлено
на кафедре иностранных языков
Печатается по решению редакционно-издательского совета
Казанского государственного технологического университета.
ISBN 978-5-7882-1038-4
Рецензенты:
доц.
Э.Р. Залялютдинова
доц. Е.А. Нелюбина
©Казанский
государственный
технологический
университет
ВВЕДЕНИЕ
Учебное пособие предназначено для студентов 2-3
курсов как для внеаудиторной, так и для аудиторной работы.
В учебное пособие включены тексты по
специальности 240502 «Технология переработки
пластических масс и эластомеров», 240501 «Химическая
технология высокомолекулярных соединений»и задания к
ним, грамматические темы, сведения о странах изучаемого
языка, а так же деловая корреспонденция, которые могут
послужить информативной базой для подготовки Интернетэкзамена.
Также в пособии представлены 4 варианта тестов
интернет-экзамена. Каждый тест содержит 34 вопроса,
которые предусматривает контроль знаний студентов по 6
дедактическим единицам:
ексика;
1) л
2) грамматика;
3) речевой этикет;
4) страноведение;
5) деловая корреспонденция;
6) чтение.
Процесс обучения предполагает сочетание
аудиторной и внеаудиторной работы с целью способствовать
развитию творческой активности, самостоятельности в
овладении иностранным языком, расширению кругозора и
активному использованию приобретенных умений в процессе
коммуникации.
Данное учебное пособие отвечает современной
концепции обучения иностранному языку, которая
направлена не только на накопление некоторой суммы
знаний, но и на создание необходимых условий для
успешного решения конкретных, возникающих естественным
образом задач межкультурной коммуникации.
Theme: Chemical compound
1. Define the tense and voice of the verbs:
they consist of, a mixture can usually be separated by simple,
atoms of a single element are not considered chemical
compounds, alloys are made
2. Translate into Russian:
consisting of two or more different chemical elements, pure
chemical elements, eight valence electrons, may not be
completely homogenous, a liquid state have some properties.
3. Revise the following verbs:
consist, held, become, require, consider, distinguish, react, trap,
heat
4. State to what parts of speech these words belong:
frequently, chemical, consisting, compound, shortened,
constituent, which, single, evaporation, mixture, intermetallic,
slightly.
Chemical compound
A chemical compound (frequently shortened to compound)
is a pure chemical substance consisting of two or more different
chemical elements that can be separated into simpler substances
by chemical reactions. Chemical compounds have a unique and
defined chemical structure; they consist of a fixed ratio of atoms]
t
hat are held together in a defined spatial arrangement by
chemical bonds. Chemical compounds can be compound
molecules held together by covalent bonds, salts held together by
ionic bonds, metallic compounds held together by metallic bonds,
or complexes held together by coordinate covalent bonds.
Substances such as pure chemical elements and elemental
molecules consisting of multiple atoms of a single element (such
as H2, S8, etc.) are not considered chemical compounds.
Elements form compounds to become more stable. They
become stable when they have the maximum number of possible
electrons in their outermost energy level, which is normally two
or eight valence electrons. This is the reason that noble gases do
not frequently react: they already possess eight valence electrons
(the exception being helium, which requires only two valence
electrons to achieve stability).
There are some exceptions to the definition above. Certain
crystalline compounds are called "non-stoichiometric" because
they vary in composition due to either the presence of foreign
elements trapped within the crystal structure or a deficit or excess
of the constituent elements. Some compounds regarded as
chemically identical may have varying amounts of heavy or light
isotopes of the constituent elements, which will make the ratio of
elements by mass vary slightly. A compound therefore may not
be completely homogenous, but for most chemical purposes it can
be regarded as such.
Compounds compared to mixtures
The physical and chemical properties of compounds are
different from those of their constituent elements. This is one of
the main criteria for distinguishing a compound from a mixture of
elements or other substances because a mixture's properties are
generally closely related to and dependent on the properties of its
constituents. Another criterion for distinguishing a compound
from a mixture is that the constituents of a mixture can usually be
separated by simple, mechanical means such as filtering,
evaporation, or use of a magnetic force, but the components of a
compound can only be separated by a chemical reaction.
Conversely, mixtures can be created by mechanical means alone,
but a compound can only be created (either from elements or
from other compounds, or a combination of the two) by a
chemical reaction.
Some mixtures are so intimately combined that they have
some properties similar to compounds and may easily be
mistaken for compounds. One example is alloys. Alloys are made
mechanically, most commonly by heating the constituent metals
to a liquid state, mixing them thoroughly, and then cooling the
mixture quickly so that the constituents are trapped in the base
metal. Other examples of compound-like mixtures include
intermetallic compounds and solutions of alkali metals in a liquid
form of ammonia.
ASSIGNMENTS
1. True or false?
1. Noble gases do not frequently react.
2. Elements don’t form compounds to become more stable.
2. Answer the questions:
1. What is a chemical compound ?
2. Why do elements form compounds ?
3. What is the main criteria for distinguishing a compound?
4. Chemical compounds have a unique and defined chemical
structure, don’they?
5. What can you say about alloys?
3. Divide the text into logical parts and find the topical
sentence of each part.
4. Retell the text in short.
Theme: Polymer
1. Give Russian equivalents to the following English
words, word combinations and chemical terms:
covalent chemical bonds, extraordinary range of properties,
synthetic materials, is based on, significant, such as, most
commonly,
glycosidic bonds, a phosphodiester bond, the list of synthetic
polymers, neoprene, polystyrene, polyethylene, polypropylene,
polyacrylonitrile, nylon, rubber.
2. Revise the following irregular verbs.
to know, to have, to be, to win, to show, to find, to become
3. State to what parts of speech these words belong:
polymeric, development, accessible, known, association, theory,
commercially, important, reacting.
4. Guess the meaning of the words in black type:
structure - structural, polymer – polymeric, connect –
connected, react – reaction, wide – widely, differ – different differently
Polymer
A polymer is a large molecule (macromolecule) composed of
repeating structural units typically connected by covalent
chemical bonds. While polymer in popular usage suggests plastic,
the term actually refers to a large class of natural and synthetic
materials with a variety of properties.
Due to the accessible in polymeric materials, they have come
to play an essential and ubiquitous role in everyday life—from
plastics and elastomers on the one hand to natural biopolymers
such as DNA and proteins that are essential for life on the other.
A simple example is polyethylene, whose repeating unit is based
on ethylene (IUPAC name ethene) monomer. Most commonly, as
in this example, the continuously linked backbone of a polymer
used for the preparation of plastics consists mainly of carbon
atoms. However, other structures do exist; for example, elements
such as silicon form familiar materials such as silicones,
examples being silly putty and waterproof plumbing sealant. The
backbone of DNA is in fact based on a phosphodiester bond(1),
and repeating units of polysaccharides(2) (e.g. cellulose) are
joined together by glycosidic bonds(3) via oxygen atoms.
Natural polymeric materials such as shellac, amber, and
natural rubber have been in use for centuries. Biopolymers such
as proteins and nucleic acids play crucial roles in biological
processes. A variety of other natural polymers exist, such as
cellulose, which is the main constituent of wood and paper.
The list of synthetic polymers includes synthetic rubber,
Bakelite, neoprene, nylon, PVC, polystyrene, polyethylene,
polypropylene, polyacrylonitrile, PVB, silicone, and many more.
Polymers are studied in the fields of polymer chemistry,
polymer physics, and polymer science.
The word polymer is derived from the Greek words πολυ-
u meaning "many"; and µέρος - meros meaning "part". The
pol
term was coined in 1833 by Joens Jakob Berzelius, although his
definition of a polymer was quite different from the modern
definition. (see Joens Jakob Berzelius#New chemical terms)
Note.
1. A phosphodiester bond is a group of strong covalent
bonds between a phosphate group and two 5-carbon ring
carbohydrates (pentoses) over two ester bonds. Phosphodiester
bonds are central to all life on Earth, as they make up the
backbone of the strands of DNA. In DNA and RNA, the
phosphodiester bond is the linkage between the 3' carbon atom of
one sugar molecule and the 5' carbon of another, deoxyribose in
DNA and ribose in RNA.
The phosphate groups in the phosphodiester bond are negativelycharged. Because the phosphate groups have a pKa near 0, they
are negatively-charged at pH 7. This repulsion forces the
phosphates to take opposite sides of the DNA strands and is
neutralized by proteins (histones
), metal ions such as magnesium,
and polyamines.
In order for the phosphodiester bond to be formed and the
nucleotides to be joined, the tri-phosphate or di-phosphate forms
of the nucleotide building blocks are broken apart to give off
energy required to drive the enzyme-catalyzed reaction. When a
single phosphate or two phosphates known as pyrophosphates
break away and catalyze the reaction, the phosphodiester bond is
formed.
Hydrolysis of phosphodiester bonds can be catalyzed by the
action of phosphodiesterases which play an important role in
repairing DNA sequences.
In biological systems, the phosphodiester bond between two
ribonucleotides can be broken by alkaline hydrolysis because of
the free 2' hydroxyl group.
2. Polysaccharides are polymeric carbohydrate structures,
formed of repeating units (either mono- or di-saccharides) joined
together by glycosidic bonds
. These structures are often linear,
but may contain various degrees of branching. Polysaccharides
are often quite heterogeneous, containing slight modifications of
the repeating unit. Depending on the structure, these
macromolecules can have distinct properties from their
monosaccharide building blocks. They may be amorphous or
even insoluble in water.
When all the monosaccharides in a polysaccharide are the same
type the polysaccharide is called a homopolysaccharide, but when
more than one type of monosaccharide is present they are called
heteropolysaccharides.
Examples include storage polysaccharides such as starch and
glycogen, and structural polysaccharides such as cellulose and
chitin.
Polysaccharides have a general formula of Cx(H2O)y where x is
usually a large number between 200 and 2500. Considering that
the repeating units in the polymer backbone are often six-carbon
monosaccharides, the general formula can also be represented as
(C6H10O5)n where 40≤n≤3000
3. In chemistry, a glycosidic bond is a type of functional group
that joins a carbohydrate (sugar) molecule to another group,
which may or may not be another carbohydrate.
A glycosidic bond is formed between the hemiacetal group of a
saccharide (or a molecule derived from a saccharide) and the
hydroxyl group of some organic compound such as an alcohol. If
the group attached to the carbohydrate residue is not another
saccharide it is referred to as an aglycone. If it is another
saccharide, the resulting units can be termed as being at the
reducing end or the terminal end of the structure. This is a relative
nomenclature where the reducing end of the di- or polysaccharide
is towards the last anomeric carbon of the structure, and the
terminal end is in the opposite direction.
In the literature, the bond between an amino group or other
nitrogen-containing group and the sugar is often referred to as a
glycosidic bond (although IUPAC seems to suggest that the term
is a misnomer). For example, the sugar-base bond in a nucleoside
may be referred to as a glycosidic bond. A substance containing a
glycosidic bond is a glycoside.
Historical development
Starting in 1811, Henri Braconnot did pioneering work in
derivative cellulose compounds, perhaps the earliest important
work in polymer science. The development of vulcanization later
in the nineteenth century improved the durability of the natural
polymer rubber, signifying the first popularized semi-synthetic
polymer. In 1907, Leo Baekeland created the first completely
synthetic polymer, Bakelite, by reacting phenol and formaldehyde
at precisely controlled temperature and pressure. Bakelite was
then publicly introduced in 1909.
Despite significant advances in synthesis and characterization
of polymers, a correct understanding of polymer molecular
structure did not emerge until the 1920s. Before then, scientists
believed that polymers were clusters of small molecules (called
colloids), without definite molecular weights, held together by an
unknown force, a concept known as association theory. In 1922,
Hermann Staudinger proposed that polymers consisted of long
chains of atoms held together by covalent bonds, an idea which
did not gain wide acceptance for over a decade and for which
Staudinger was ultimately awarded the Nobel Prize. Work by
Wallace Carothers in the 1920s also demonstrated that polymers
could be synthesized rationally from their constituent monomers.
An important contribution to synthetic polymer science was made
Соседние файлы в предмете [НЕСОРТИРОВАННОЕ]