Giáo trình tiếng anh trong kỹ thuật hóa học phần 1

Trong phần một tác giả chọn các bài khoá liên quan đến những kiến thức cơ bản của Hoá học, những chuyên đề cơ bản của Hoá học.. Trong phần cuối cùng tác giả biên soạn ba bài cơ bản về kỹ

GIÁO TRÌNH TIẾNG ANH TRONG KỸ THUẬT HÓA HỌC

PGS.TS BÙI THỊ LỆ THỦY

GIÁO TRÌNH

TIẾNG ANH

TRONG KỸ THUẬT HÓA HỌC

NHÀ XUẤT BẢN GIAO THÔNG VẬN TẢI

HÀ NỘI - 2019

LỜI NÓI ĐẦU 1

PART 1 THE BASIC UNITS 6

I.1 TYPICAL UNITS 7

UNIT 1 SOME CONCEPTS IN CHEMISTRY 7

UNIT 2 HYDROCARBONS 10

UNIT 3 CHEMICAL KINETIC AND CATALYSIS 14

UNIT 4 ANALYTICAL CHEMISTRY 16

UNIT 5 CHEMICAL THERMODYNAMICS 19

UNIT 6 EMULSIONS 23

UNIT 7 PLASTICS IN THE CHEMICAL AGE 27

UNIT 8 ENZYMES 31

I.2 ADDITIONAL UNITS 34

UNIT 9 PROPERTIES OF GELS 34

UNIT 10 SOLVENT PROPERTIES OF SURFACTANT SOLUTIONS EMULTION POLYMERIZATION 37

UNIT 11 THE NATURE OF RUBBER - LIKE ELASTICITY 39

UNIT 12 THERMOPLASTIC ELASTOMERS THERMOSETTING AND THERMOPLASTIC MATERIAL 42

UNIT 13 THERMOPLASTIC ELASTOMERS 45

UNIT 14 ABS PLASTIC 49

UNIT 15 HAFNIUM 52

REFERENCES 56

PART 2 THE CHEMICAL ENGINEERING UNITS 57

UNIT 16 TYPES OF REACTORS 58

UNIT 17 HEAT TRANSFER AND ITS APPLICATIONS 62

UNIT 18 EXTRACTION WITH SOLVENTS 67

UNIT 19 INTRODUCTION TO DISTILLATION AND ATMOSPHERIC DISTILATION 72

UNIT 20 VACUUM DISTILLATION 77

UNIT 21 STEAM DISTILLATION 81

UNIT 22 CRYSTALLIZATION 86

UNIT 23 ADSORPTION 90

UNIT 24 EVAPORATION 93

UNIT 25 CHROMATOGRAPHY 97

UNIT 26 LIQUIS-SOLID CHROMATOGHRAPHY 100

REFERENCES 104

PART 3 THE PETROCHEMICAL INDUSTRY AND REFINERY UNITS 105

III.1 TYPICAL UNITS 106

UNIT 27 ON OIL AND GAS INDUSTRY 106

UNIT 28 COMPOSITION OF PETROLEUM 108

UNIT 29 BASIC PHYSICO-CHEMICAL PROPERTIES OF PETROLEUM AND PETROLEUM PRODUCTS 112

UNIT 30 BASIC PHYSICO-CHEMICAL PROPERTIES OF PETROLEUM AND PETROLEUM PRODUCTS (CONTINUED) 117

UNIT 31 DISTILLATION OF PETROLEUM 121

UNIT 32 THERMAL PROCESSES IN REFINERY 126

THERMAL CRACKING 126

UNIT 33 CATALYTIC PROCESSES IN REFINERY 131

III.2 ADDITIONAL UNITS 136

UNIT 34 CATALYTIC CRACKING OF PETROLEUM 136

UNIT 35 CATALYTIC REFORMING OF PETROLEUM 142

REFERENCES 147

PART 4 ACADEMIC WRITING 148

UNIT 36 INTRODUCTION TO ACADEMIC WRITING 149

UNIT 37 TYPES AND STRUCTURE OF ACADEMIC WRITING 153

UNIT 38 HOW TO WRITE A SUCCESSFUL 157

SCIENTIFIC MANUSCRIPT 157

REFERENCES 161

LỜI NÓI ĐẦU

Giáo trình này được biên soạn cho những sinh viên năm cuối của ngành Kỹ thuật Hoá học Giáo trình nhằm bổ sung cho sinh viên các từ vựng, tổ hợp từ, thuật ngữ, cấu trúc ngữ pháp hay gặp trong những tài liệu khoa học kỹ thuật, giúp sinh viên làm quen với việc dịch Anh-Việt và ngược lại, viết một văn bản khoa học bằng tiếng Anh

Nội dung của giáo trình gồm 4 phần Các bài học trong các phần được biên soạn tăng dần theo mức độ chuyên sâu trong lĩnh vực hoá học

Trong phần một tác giả chọn các bài khoá liên quan đến những kiến thức cơ bản của Hoá học, những chuyên đề cơ bản của Hoá học Mỗi bài khoá đều sắp xếp theo trật tự logic từ bài đọc hiểu, các bài tập để sinh viên ôn luyện, từ đó giúp sinh viên làm quen với những từ, tổ hợp từ và tập trung vào kỹ năng đọc hiểu, dịch từ tiếng Anh sang tiếng Việt và ngược lại

Phần hai gồm những bài khoá liên quan đến lĩnh vực Kỹ thuật Hoá học như lò phản ứng, những kỹ thuật tách chất phổ biến và thông dụng nhất Cấu trúc bài khoá ở phần này cũng tương tự như ở phần một Các bài tập đi kèm làm cho bài khoá thêm sinh động và đưa vào những cấu trúc ngữ pháp hay gặp trong khoa học

Phần ba là những bài khoá tập trung vào lĩnh vực Hoá dầu Nội dung mỗi bài đều gắn với chuyên môn sâu của sinh viên Sau mỗi bài đều có bài tập để sinh viên rèn luyện khả năng đọc, dịch và viết tiếng Anh

Trong phần cuối cùng tác giả biên soạn ba bài cơ bản về kỹ thuật viết một văn bản khoa học trong lĩnh vực Kỹ thuật Hoá học, giúp sinh viên nắm được những bước cơ bản và sườn của một bản thảo bài báo khoa học

Tác giả xin trân trọng cảm ơn các đồng nghiệp đã đóng góp ý kiến để hoàn thành cuốn sách này Xin chân thành cảm ơn sự quan tâm của độc giả và mong nhận được những ý kiến góp của các độc giả và các bạn đồng nghiệp để cuốn sách ngày một hoàn thiện hơn

Tác giả

PART 1 THE BASIC UNITS

I.1 TYPICAL UNITS

UNIT 1 SOME CONCEPTS IN CHEMISTRY

Structure of Atoms According to Dalton’s atomic theory, a chemical element is

material composed of only one type of atom Atoms are very small particles that cannot be separated into simpler substances and that singly or in combination constitute all matter

All atoms are constructed from the three particles: the electron, proton, and neutron Both neutrons and protons occupy the nucleus, which is in the center of the atom The electrons orbit around the nucleus Each atom contains equal number of electrons and protons, therefore, atoms are neutral An atom of one element is distinguished from an atom of another element by its number of protons The number of proton in the atomic nucleus is called the atomic number Z of an element For instance, carbon atoms contain six protons and six electrons; therefore, the atomic number of carbon is 6 The total mass of an atom is almost entirely by the number of protons and neutrons because the mass of electrons is so much smaller

The atoms of almost element have the same proton number but different neutron number; therefore they have different mass number These atoms are called isotopes For example, helium exists as helium-3 or He-3 (its nucleus contains 2 protons but only 1 neutron) or as helium-4 or He-4 (2 protons and 2 neutrons) These two examples are called isotopes of helium

The elements are arranged in the periodic table, the invention of which is generally attributed to the 19th century Russian chemist Dimini Mendeleev In the standard periodic table, the elements are listed in order of increasing atomic number (the number of protons in

the nucleus of an atom) A new row (period) is started when a new electron shell has its first

electron Elements containing the same number of electron layers are arranged in the same period while elements with the same number of electrons in a particular subshell fall into the same columns

Molecules, substances, and chemical compounds Molecules are composed of the

atoms of one or more elements Nitrogen exists as nitrogen molecules in atmosphere, each molecule contains two nitrogen atoms Its symbolic representation is N2 Water molecule contains one oxygen atom and two hydrogen atoms Compounds are composed of the atoms of one or more elements N2 is an elementary substance and water is a compound but both of

them are called substances

Exercises 1.1 Read and translate into Vietnamese

Concept, structure, atom, atomic, theory, element, material, compose, substance, particle, combination, constitute, matter, electron, proton, neutron, neutral, nucleus, orbit, distinguish, atomic number, mass number, helium, arrange, periodic table, attribute, electron shell, subshell, molecule, substance, elementary substance, compound

1.2 Answer the following questions

1 What is an element?

2 What is an atom?

3 How many kinds of particles are there in every atom? What are they?

4 What is the atomic number of an element?

5 How can we determine the mass of an atom?

6 What is a molecule?

7 Please distinguish an elementary substance and a compound

1.3 Translate into Vietnamese paying attention to the words in bold type

1 The name ABS, based on the first letters of each of the monomeric components has been

adopted for this family

2 By introducing acrylonitrile monomer into a similar system, a significant improvement in

all these properties is obtained, as well as outstanding toughness and resistance

3 Various combinations of properties are possible, thus making these polymers most attractive for a larger number of current and newly developed applications

4 ABS plastics are extremely useful and versatile, since ease of processing and forming allows them to be used for a great number of applications

5 The strength of a fabricated item produced from ABS plastic is dependent on a number of variables

1.4 Translate into English

1 Nguyên tử là phần tử nhỏ nhất của vật chất có thể tồn tại độc lập

2 Nguyên tử được cấu tạo từ proton, electron và nơtron Electron tích điện âm, ptoton tích điện dương còn nơtron không mang điện

3 Trong một nguyên tử, số proton bằng với số electron nên nguyên tử luôn trung hòa về điện

4 Vì khối lượng của eletron rất nhỏ so với khối lượng của nơtron và proton nên khối lượng nguyên tử được tính xấp xỉ là tổng khối lượng của proton và nơtron

5 Phân tử chứa các nguyên tử của một hoặc nhiều nguyên tố

6 Các hợp chất bao gồm các nguyên tử của hai hay nhiều nguyên tố

7 Các hạt proton và neutron nằm ở trung tâm và tạo ra hạt nhân còn các electron chuyển động xung quanh hạt nhân tạo ra các lớp electron

8 Đồng vị là các nguyên tử của cùng nguyên tố có số nơtron khác nhau

9 Các nguyên tố trong cùng một chu kỳ có cùng số lớp electron

10 Các nguyên tố trong cùng một nhóm có cùng số electron ở lớp ngoài cùng, do đó, chúng

UNIT 2 HYDROCARBONS

Hydrocarbons are compounds containing only carbon and hydrogen atoms

1 Paraffin hydrocarbons (alkanes)

Their general formula is CnH2n+2, where n is the number of carbon atoms Each next hydrocarbon can be obtained from the previous one by substituting a methyl group CH3 for the extreme hydrogen atom in the chain:

CH4 C2H6 C3H8 C4H10

methane ethane propane butane

The paraffin hydrocarbons are the most stable of the lot because all valence bonds are fully satisfied as indicated by the single linkage Most reactions involve the replacement of hydrogen atoms with other atoms, the carbon linkage remains stable

Under common conditions, the hydrocarbons from CH4 to C4H10 are gaseous, those from C5H12 to C15H32 are liquids (they enter the composition of gasoline, kerosene, and diesel- fuel fractions), and those from C16H34 are solid (paraffins)

Beginning from the fourth term in the series (butane C4H10), hydrocarbons may exist

in two or more forms differing in the structure For instance, butane may exist in two forms: n-butane and isobutane Compounds which have the same chemical formula but different molecular structure are called isomers

The number of isomers increases for each next hydrocarbon in the series Hydrocarbons of the formula C13H28 may have 802 isomers, those of the formula C14H30,

1858, and so on Thus, the composition of petroleum is quite complicated Isomers possess different physical and chemical properties For instance, heptane of normal structure (n-

C7H16) has an octane number of zero, whereas isooctane (iso- C8H18) has an octane number of 100

2 Naphthenic Hydrocarbons (Cycloalkanes)

Their general formula is CnH2n They were discovered by V.V Markovnikov, a

prominent Russian chemist, when studying petroleum of Caucasian deposits

In their chemical properties; naphthenic hydrocarbons are similar to paraffins, but differ from the latter in having a cyclic structure

Cyclopentane and cyclohexane derivatives are especially important for the quality of petroleum and petroleum products

3 Benzene Hydrocarbons (Arenes)

Arenes of the benzene series have the general formula CnH2n-6 The cyclic structure of arenes differs from that of naphthenes by the presence of double bonds on the aromatic ring

If one or more atoms of hydrogen in the ring are replaced by a methyl (-CH3) or an ethyl

(-C2H5) group, other arenes (toluene, xylenes and ethylbezene) are formed Arenes are valuable raw materials for chemical technology and the manufacture of antiknock gasoline

4 Unsaturated Hydrocarbons (Olefins)

Hydrocarbons of the ethylene series have the general formula is CnH2n, are characterized by a double bond in the molecule (ethylene C2H4, propylene C3H6, butylenes

C4H8, amylenes C5H10, etc.) and may be of either normal or isomeric structure

They are not present in crude petroleum, but constitute an appreciable part of the products obtained in thermal and some catalytic processes of petroleum processing These hydrocarbons have high reactivity and are used for the manufacture of some important products, such as polyethylene, polypropylene, ethylene and propylene oxides and their derivatives

Along with olefins, some less saturated hydrocarbons, with two double bonds in the structure, such as diolefins, can form in petroleum processing These are extremely unstable and for that reason should not be present in final petroleum products Some of them (butadiene C4H6 and isoprene C5H8) are obtained intentionally from petroleum and used for the manufacture of synthetic rubber and like products

Exercises 2.1 Read and translate into Vietnamese

Paraffin, general formula, substitute, methane, ethane, propane, butane, stable, satisfy, linkage, single, double, triple, bond, gasoline, kerosene, gaseous, fuel, petroleum, diesel, fraction, solid, isomer, isomeric, heptane, isooctane, naphthene, naphthenic, cycloalkane, prominent, cyclopentane, cyclohexane, derivatives, arene, benzene, aromatic, toluene, xylene, ethylbenzene, antiknock, unsaturated, ethylene, acetylene, amylene, butylene, constitute, appreciable, petroleum processing, polyethylene, polypropylene, propylene oxides, diolefin, unstable, butadiene, synthesis, synthesize, synthetic, rubber

2.2 Answer the following questions

1 What kinds of substances are hydrocarbons?

2 What is the general formula of alkanes?

3 What are isomers?

4 What can you say about the properties of isomers?

5 Which compounds are called cyclic compounds?

6 What are benzene hydrocarbons or arene?

7 What are the uses of benzene and benzene hydrocarbons?

8 What are properties of unsaturated hydrocarbons?

9 What are the uses of unsaturated hydrocarbon?

2.3 Fill the following schemes with suitable expressions

Funnel, filter paper, mixture, residue, glass rod, filtrate, beaker, and stand

Figure 1 Laboratory setup for filtration experiment

2.4 State the purpose of the system and describe its operation

Figure 2 Laboratory setup for vacuum filtration experiment

Moisten the filter paper with the solvent used in the crystallization process and apply suction before the filtration is started The suspension of crystals is then poured onto the filter

in such a way that a layer of uniform thickness is collected If crystals adhere to the walls of the flask in which crystallization was carried out, they may be washed out with some of the filtrate

8

8

2.5 Fill the following schemes with suitable expressions

Support stands, water in, water out, pot, thermometer, rubber tubing, adapter, receiver, thermometer adapter, condenser, clamp, boiling chips, distilling head, support ring, electric

flask heater

Figure 3 Laboratory setup for simple distillation experiment

2.6 Translate into English

1 Hydrocacbon là các hợp chất chỉ chứa cacbon và hydro

2 Trong dầu mỏ chỉ chứa các hydrocacbon paraffin, naphten và aromatic vì chúng bền Các hydrocacbon không no chỉ tạo ra trong quá trình chế biến dầu mỏ

3 Các hydrocacbon không no có hoạt tính vì chúng có các liên kết bội không bền

4 Các paraffin và naphten có hoạt tính hoá học thấp do phân tử của chúng chỉ chứa các liên kết đơn (bão hoà)

2.7 Write a short summary of the text

UNIT 3 CHEMICAL KINETIC AND CATALYSIS

Chemical kinetics, also known as reaction kinetics, is an important part of

chemistry Chemical kinetics study of how experimental conditions can influence the speed and yield of a chemical reaction Investigation of chemical kinetics can give us the information about the reaction's mechanism as well as the mathematical models that can describe the characteristics of a chemical reaction

There are many factors that determine the rate of a reaction Temperature is an important factor which affects the reaction Almost the reactions need energy by raising the temperature The higher temperature the higher the atoms, molecules, and ions move which leads to the frequency of collision increases High frequency of collision helps the particle to overcome the activation barrier High concentration of the reactants also increases the rate of

a reaction If the reactant molecules are closed the collisions become more frequent which makes the reaction more likely happens

In addition, the rate depends also upon physical form of reactant, the intimacy of their mixture, the pressure and solvents, the special physical circumstances such as irradiation with visible light, ultraviolet light, X-rays, neutrons, and the presence of other substances which affect the reaction but are not changed by it (catalysts)

A catalyst can accelerate a chemical reaction because it let the reaction takes place by

an alternative pathway with lower activation energy barrier Catalyst reacts to form a temporary intermediate which then regenerates the original catalyst in a cyclic process In the presence of a catalyst, less free energy is required to reach the transition state, but the total free energy from reactants to products does not change Many kinds of catalysts are used up

to now such as acid, base, transition metal, complex, enzyme… Depend on the state of the catalytic reaction system catalysts may be classified as either homogeneous or heterogeneous The molecules of a homogeneous catalyst are dispersed in the same phase (usually gaseous or liquid) as the reactant molecules The molecules of a heterogeneous catalyst are not in the same phase as the reactants, which are typically gases or liquids that are adsorbed onto the surface of the solid catalyst Enzymes and other biocatalysts are often considered as a third category

The detailed mechanism of catalysis is complex Kinetically, catalytic reactions are typical chemical reactions; i.e the reaction rate depends on the frequency of contact of the reactants in the rate-determining step Usually, the catalyst participates in this slowest step,

and rates are limited by amount of catalyst and its "activity"

Rate equation for a chemical reaction is an equation that shows the relationship between reaction rates and the concentrations or pressures of the reactants and constant parameters Depending on the rate equation we can distinguish the zero order, first order, second order reactions and so on

Exercises 3.1 Read and translate into Vietnamese

Chemical kinetic, kinetic, kinetically, catalysis, catalyst, catalytic, mechanism, mathematical model, factor, frequency, collision, activation, reactant, intimacy, circumstance, irradiation, visible, light, ultraviolet light, X-rays, accelerate, alternative, pathway, regenerate, cyclic process, free energy, transition metal, homogeneous, heterogeneous, adsorb, rate determining step, rate equation, zero order

3.2 Answer the following questions

1 What is catalysis?

2 What is a catalyst?

3 Compare the homogeneous and heterogeneous catalysts!

4 Which kinds of catalysts are there?

5 What is the role of a catalyst?

6 What are the inhibitors and poisons of a reaction?

7 What is the rate-determining step?

8 Do catalysts change during the reaction?

3.3 Translate the following sentences into Vietnamese

1 Lewis found water and air to be thermodynamically unstable with respect to the formation

of nitric acid

2 Metastable or unstable compounds can be treated by the methods of thermodynamics, provided that they have a lifetime sufficiently long for thermodynamic measurements to be made

3 Scientists consider adsorption from solutions to be physical or chemical

4 It is noteworthy that in the case of phosphate buffers, the increase of pH is accompanied

by a drop of interface tension between the two phases

3.4 Translate into English

1 Chất xúc tác là chất làm tăng tốc độ phản ứng nhưng bản thân nó không bị biến đổi sau phản ứng

2 Vai trò của chất xúc tác là làm giảm năng lượng hoạt hóa của phản ứng

3 Ở cùng điều kiện nhiệt độ và nồng độ chất phản ứng, khi năng lượng hoạt hóa của phản ứng giảm đi thì tốc độ phản ứng tăng lên

4 Chất xúc tác thường tham gia vào giai đoạn quyết định tốc độ phản ứng hay là giai đoạn chậm chất của phản ứng

3.5 Write a short summary of the text

UNIT 4 ANALYTICAL CHEMISTRY

One should keep in mind that industrial analysis is not necessarily a routine, boring occupation It can be frustrating at times but it can also be fascinating, instructive, humorous, and even exciting It is usually pleasant if one dedicates himself to learning about what goes

on in chemical systems The key for enjoying analytical work lies in knowing that the results will be useful and important

Problem - solving in analytical chemistry

An analytical chemist should know enough about existing methodologies to choose the best one for application to a given sample, perhaps modifying it if necessary to fit the particular situation, and that there is also an analytical science which seeks the improvement

of analytical methodologies with regard to scientific problems Nowadays, with more and more instrumental methods in vogue, the analysts and determinators are coming closer together

To be a good chemist one must first be a good analytical chemist We can teach instrumental analysis in industry, but we should not teach basic chemistry

Mercury? Questions and answers

Some of you may be interested in the question of mercury and its determination in the environment This is a fascinating question with many aspects It illustrates again the importance of analytical chemists looking at the whole picture

Swedish scientists had developed a gas chromatographic method for the determination

of alkyl and aryl mercuric compounds extracted from fish with benzene and dilute hydrochloric acid They were interested in those compounds because of their use as slimicides, but it turned out that regardless of what compound was used, the mercury found in fish was present as a monomethylmercuric ion

A number of questions about the behavior of mercury remain to be answered Several theories have been proposed as to how mercury might have gone from inorganic form in water or bottom sediment, into a methylated form of a fish One theory assumes anaerobic conversion in the mud to volatile dimethyl mercury which enters fish via the gills Another assumes aerobic conversion to monomethyl mercury by bacteria, with subsequent transfer up

to the food chain Still another assumes that a fish itself can methylate mercury taken in either through the gills as elemental vapor, or via the stomach as inorganic ions, or in an adsorbed state in silt particles Before all these questions can be answered, we need to develop highly sensitive methods for each individual form of mercury At present the most sensitive methods can go down only to about 0.05-ppm inorganic mercury in water

At the conference on environmental mercury contamination in 1970 in Ann Arbor, Michigan, USA a number of sources from which mercury may enter the environment were mentioned Among them were the burning of fossil fuels, use of mercurial compounds for fungicides in agricultural seed treatments, use of elemental mercury in the electrical industry for manufacture of batteries and mercury vapour lamps, use of mercuric catalysts, and the

disposal of domestic sewage sludges It will be up to analytical chemists to evaluate all of the sources and to provide the data on which proper action can be based This will be true not only for mercury, but also for all environmental contaminants

It is interesting that both Finish and Swedish chemists have found fairly high content

in fish from certain lakes in northern parts of their countries, remote from any known source

be employed However, hair can be analyzed by the atomic absorbance method following the digestion procedure used for fish analysis A 100-mg sample is sufficient for hair in the range

of 1 to 10 ppm

Exercises 4.1 Read and translate into Vietnamese

Analysis, analytical, routine, occupation, frustrating, fascinating, instructive, humourous, pleasant, dedicate, methodology, modify, particular, vogue, determination, determinator, instrument, instrumental, mercury, mecuric, environment, fascinating, aspect, illustrate, chromatographic, dilute, alkyl, aryl, extract, benzene, slimicide, regard, regardless, monomethylmercuric, sediment, methylate, anaerobic, mud, aerobic, gill, assume, inorganic, organic, volatile, dimethyl mercury, subsequent, transfer, chain, stomach, sensitive, silt, individual, contaminate, contamination, contaminant, mention, fossil fuel, fungicide, agriculture, agricultural, battery, disposal, domestic, sewage, sludge, evaluate, source, remote, pollution, approximate, expose, exposure, intensity, absorbance, digestion, sufficient

4.2 Answer the following questions

1 What is the key for enjoying analytical work?

2 How is industrial analysis?

3 What should an analytical chemist know?

4 Which compounds of mercury are present in fish?

5 How has mercury transferred from inorganic form to methylated form?

4.3 Translate into Vietnamese paying attention to the finite and non- finite forms of the verb

1 Having developed a gas chromatographic method for the determination of alkyl and aryl compounds the Swedish scientists got interested in those compounds

2 Swedish scientists developed a gas chromatographic method for the determination of alkyl and aryl mercuric compounds extracted from fish

3 The chemists extracted fairly high mercury contents from fish

4 The scientists found high mercury contents in fish from certain lakes, remote from any known source of pollution

5 Mercury found in fish was present as a monomethylmercuric ion

4.4 Translate into Vietnamese paying attention to the pronoun “ one”

1 One should keep in mind that industrial analysis is not necessarily a boring occupation

2 It is pleasant if one dedicates himself to learning about what goes on in chemical systems

3 An analytical chemist should know enough about existing methodologies to choose the best

one for application

4 To be a good chemist one must be first of all a good analytical chemist

4.5 Translate into Vietnamese paying attention to the Model Verbs + Perfect infinitive

1 It was realized that drying may have caused some denaturation, but whatever the change it should not have affected the amino acid composition of the proteins

2 It goes without saying that any of the acid derivatives (amide, ester, etc.) might have been prepared either from benzoyl chloride or benzoic anhydride instead of from benzoic acid

3 The mercaptans obtained could have been oxidized in alkaline solutions to disulfides

4 Zincate solutions could have been prepared by dissolving ZnO in aqueous KOH

4.6 Read the following model of a summary

The article “The pains and pleasures of industrial analytical chemistry” discusses what

an analytical chemist should know about existing methodologies and presents a gas chromatographic method for determination of alkyl and aryl mercuric compounds extracted from fish with benzene and dilute hydrochloric acid

The paper provides examples of fairly high mercury content in fish from certain lakes

of Sweden and Finland, which are remote from any known source of pollution and of finding mercury in the hair of a person exposed to it

The article illustrates and describes the importance of an analytical chemist who should use the best methodology to a given sample modifying it to fit the particular situation

UNIT 5 CHEMICAL THERMODYNAMICS

The science of thermodynamics concerns the chemical and physical processes, which involve the interconversion of various forms of energy, and it is not confined to the relation between heat and mechanical energy It is developed mathematically on the basis of a number

of postulates, which have been supported by experiments

Although its application to chemical processes quite general, thermodynamics is not at all concerned with either the rate of a process or the mechanism of it Thermodynamics is based on two fundamental laws, called the first and second laws of thermodynamics The two laws of thermodynamics constitute one of the most powerful tools of physical chemistry

Of fundamental importance to thermodynamics is the concept of equilibrium state Thermodynamic equilibrium in the true sense refers to a condition in which the properties of a system are absolutely unchanging with time so that, if the system is disturbed slightly in some way, it will return to essentially the same condition after the disturbing force is removed This latter criterion may differentiate between a true state of equilibrium and a metastable one If a metastable equilibrium is disturbed, as, for example, by introduction of a catalyst or by local heating, it may spontaneously undergo a drastic change to some new state

Consider a container filled with chlorine gas Provided that the container is sealed and thermally insulated from its surroundings a state of true thermodynamic equilibrium will be established in which the temperature and pressure are uniform If we disturb the system by shining a light on it, some of the chlorine molecules will absorb radiation and dissociate into atoms When we turn off the light, the chlorine atoms recombine and the system, except for the addition of a small amount of energy from the light beam, returns to its original condition

By way of contrast, a mixture of hydrogen and chlorine is metastable Although chlorine and hydrogen react with one another at room temperature, the rate is so slow as to be virtually undetectable Hence the system seems to behave in just the same way as the pure chlorine system, in which uniform temperature and pressure are established However, if we direct a beam of light through this mixture, it explodes, forming hydrogen chloride and evolving a large amount of heat After being disturbed in this way, the system can not revert spontaneously to its original condition In fact, the change, which does occur (the explosion),

is a state of true thermodynamic equilibrium

Although thermodynamics cannot deal with the rate at which reactions occur, it does establish the direction in which reaction can proceed Metastable or unstable compounds can

be treated by the methods of thermodynamics, provided that they have a lifetime sufficiently long for thermodynamic measurements to be made This requirement may vary, depending on the type of experiment, from a minute fraction of a second to hours, or even days In this regard, one can make the distinction between substances, which exits by virtue of its thermodynamic stability, or by reason only of its slow rate of reaction or decomposition

There is a wide range in degree of inertness of unstable system Diamond, on the one hand, is inert to the extent that there is no observable conversion (under ordinary conditions)

to the stable state of graphite At the other extreme are such unstable substances as a supercooled liquid, or a sensitive explosive In either of these cases, only a slight perturbation

is necessary to change these systems drastically Lewis and Ranall in their classic treatment of thermodynamic found that water and air, although inert, are thermodynamically unstable with respect to the formation of nitric acid

Those substances, which are quite inert chemically, can generally be treated by the methods of thermodynamics

As an example, both NO and NO2 are unstable with respect to decomposition into their elements, yet we can not only consider the reaction:

2NO2 → 2NO + O2but also study the equilibrium by a direct experiment

Exercises 5.1 Read and translate into Vietnamese

Thermodynamics, concerns, involve, interconversion, confine, mechanical, mathematical, postulate, application, general, fundamental, constitute, equilibrium, absolute, unchanging, distribute, essential, disturb, metastable, disturb, criterion, differentiate, spontaneously, drastic, provided that, thermally, insulated, disturb, shine, absorb, radiation, dissociate, chlorine, recombine, beam, original, constract, virtually, detect, undetectable, establish, explode, explosion, explosive, evolve, heat, revert, deal with, lifetime, measurement, vary, minute, distinction, decomposition, inert, inertness, degree, diamond, observable, graphite, extreme, supercool, sensitive, perturbation, treat

5.2 Answer the following questions

1 What does the science of thermodynamics deal with?

2 What are the main laws of thermodynamics?

3 What is meant under thermodynamic equilibrium?

4 Thermodynamics establishes the direction, in which a reaction proceeds, doesn't it?

5 What mixtures are considered to be metastable?

6 What conclusions did Lewis and Ranall draw?

5.3 Translate the following sentences paying attention to the words in bold type

1 Water and air are thermodynamically unstable with respect to the formation of nitric acid

2 The preparation of smokes has already been referred to in the scientific journal

3 The inert dust presumably takes up in virtue of its heat capacity, which would otherwise be

available for raising more coal dust to its ignition point

4 The amino acids are amphoteric, i.e., can act either as acids by virtue of the carboxyl, or as bases by virtue of the amino group

5 With respect to catalytic activity, metals considerably exceed other catalysts for many

reactions

6 Oxide catalysts have provided interesting systems for the study of electronic factors in

catalysis

7 Provided the oxidation directly after chlorination is carried out at sufficiently high pH,

little damage is done to the cellulose

8 Synthetic rubbers possess a marked advantage over natural ones by reason of the diversity

of properties they affect

5.4 Translate the following derivatives into Vietnamese

1 Catalysant, catalysate, catalysis, catalyst, catalytic, catalytical, catalysator, catalyzed, catalyzer

2 Stability, stabilization, stabilizator, stabilize, stabilizer, stabilizing, stable

5.5 Form nouns from the following verb

establish explode fill occur perturb provide require surround

behave combine convert differentiate dissociate distinguish disturb direct equilibrate

5.6 Translate the following sentences into Vietnamese paying attention to conditional sentences

1 If a molecule with a lone pair of electrons is adsorbed on a transition metal, it will donate

4 Were gypsum heated to a much higher temperature than 120oC, it would lose all its water

5.7 Translate into English

1 Định luật thứ nhất của nhiệt động học được xem là định luật bảo toàn năng lượng

2 Cân bằng nhiệt động có nghĩa là trạng thái mà ở đó tính chất của hệ không bị thay đổi theo thời gian

3 Như đã biết nội năng của một chất phụ thuộc vào trạng thái của nó nghĩa là phụ thuộc vào nhiệt độ, áp suất, dạng tinh thể

4 Theo định luật thứ hai của nhiệt động học thì cân bằng không phụ thuộc vào cách thức mà

nó đạt tới

5.8 Write a short summary of the text

UNIT 6 EMULSIONS

An emulsion represents a disperse system in which the phases are immiscible or partly immiscible liquids

In nearly all emulsions, one of the phases is aqueous and the other is oil If the oil is

disperse phase, the emulsion is termed an oil in water (o/w) one If the aqueous medium is the disperse phase, the emulsion is termed a water in oil (w/o) one

If one shakes vigorously a vessel containing two immiscible liquids, both liquids are broken up into the droplets whose size depends upon the viscosity of the liquid, surface, interfacial tensions and the vigor of the shaking As soon as the mechanical dispersive action ceases, the droplets begin to coalesce in order that the total surface free energy may be reduced Most often, particularly in the case of two pure liquids, the coalescence process is rapid, and within a very few minutes the system consists only of two liquid layers In the

presence of the small amounts of additional components, termed emulsifiers, the rate of

coalescence of the droplets may be greatly reduced Emulsions are intrinsically unstable, thus resembling lyophobic colloids Three distinct kinds of instability are found to exist; each may

be of great importance in industrial products

Emulsions may “cream”, i e separate into layers of aqueous phase with a concentrated layer of oil droplets floating on the top, the rate depending primarily on the viscosity of the aqueous phase, the size of the droplets, and the density difference between the aqueous phase and the droplets They may also flocculate as do other lyophobic colloids The flocs, being larger than individual drops, have a higher creaming rate

Finally, the drops may coalesce giving a separated bulk layer of the once emulsified liquid, in which case re-emulsification can be affected only by drastic mechanical action

No satisfactory quantitative theory of the emulsion stability has yet been developed It

is nevertheless becoming apparent in the case of coalescence that it is the structure of the interfacial film, which is controlling the behaviour of the system For flocculated o/w emulsions the rate of coalescence is linearly dependent on the concentration of the adsorbed emulsifier in the interfacial film, and appears to extrapolate to zero at complete coverage of the surface of droplets

It might be thought that dilute emulsions would be ideal system on which to test theories of the flocculation of lyophobic colloids Many industrially important emulsions are

“stabilized” (given long life) by the use of solids as emulsifiers

Exercises 6.1 Read and translate into Vietnamese

Emulsion, represent, disperse, phase, immiscible, aqueous, term, shake, vigorously, droplet, viscosity, surface, interfacial, tension, vigor, mechanical, dispersive cease, coalesce,

coalescence, additional, component, emulsify, emulsifier, intrinsical, lyophobic, colloid, distinct, instability, cream, floating, floc, bulk, emulsify, re-emulsification, satisfactory, nevertheless, apparent, interfacial film, interfacial, extrapolate, coverage

6.2 Answer the following questions

1 What is an emulsion?

2 What emulsions are widely known?

3 What emulsions phases do you know?

4 What happens if one shakes vigorously a vessel containing two immiscible liquids?

5 When is the coalescence process rapid?

6 In what way can industrially important emulsions be “stabilized”

6.3 Translate the following derivatives

1 disperse, dispersed, disperser, dispersing, dispersion, dispersity, dispersive

2 emulsification, emulsifier, emulsify, emulsifying, emulsion

3 miscibility, miscible, mix, mixer, mixed, mixing, mixture

4 Polymer, polymeric, polymerize polymerization, polymerize, polymerized, polymerizing

6.4 Translate the following sentences paying attention to the words in bold type

1 Water dispersible dye is a good example of an emulsion in which the pigment helps to

control the emulsion stability

2 Polyformaldehyde is used for the manufacture of many consumer goods

3 Latex foam from Government Rubber Styrene (GRS) of the proper type is good in colour,

pore structure, and ageing but rather lacking in strength

4 Even with a high alkali reserve, the storage life of neoprene latex is not as good as many

other latices

5 Neoprene is very desirable for dipped goods where special service conditions are required

6 Gum Arabic is a fairly goods dispersing agent and has one desirable feature - good

ultraviolet resistance

7 The extensive data obtained in emulsion polymerization of methyl methacrylate are in good agreement with the assumption that the rate of reaction at high conversion is governed only

by the diffusion rate of the monomer and the radical end of the polymeric chains

6.5 Translate the following sentences paying attention to the negative pronoun "no”

1 No satisfactory quantitative theory of emulsion stability has yet been developed

2 The difference between suspension and emulsion polymerization points to a process of

formation of particle in the latter, whereas no such process occurs in suspension reactions

3 No equipment embodying brass or bronze should be allowed to come into contact with

latex or its compounding ingredients at any stages of the manufacture

4 No synthetic high polymers are chemically pure substances in the strict sense

6.6 Translate the following sentences and states the function of the pronounce “one”

1 In nearly all emulsions, one of the phases is aqueous and the other is an oil

2 The colloidal state for a substance is one in which it exhibits colloidal properties

3 If one shakes vigorously a vessel containing two immiscible liquids, both liquids are

broken up into droplets

4 If the oil is the disperse phase, the emulsion is termed an oil in water one, if the aqueous medium is the disperse phase, the emulsion is termed a water in oil one

6.7 Translate the following sentences into Vietnamese paying attention to the use of verb

“to do”

1 Emulsions may flocculate, as do other lyophobic colloids

2 When polymerization does take place, average molecular weights in the thousands are

obtained

3 Reinforcing agents did not generally have the effect on latex rubber that they did on

milled rubber

4 The experiments conducted show that adhesion does increase for a time after curing, but

that it comes to a stable value during the first 24 hours

6.8 Translate into Vietnamese paying attention to the rule of Sequence of Tenses

1 Berzelius stated that rubber could be redispersed

2 It was known that ultraviolet light had a harmful influence on a rubber surface and caused photochemical effects on antioxidants

3 Dent assumed that in the alkali halides the positive and negative ions in the surface remained coplanar

4 Willbourne assumed that the methyl absorptivity was constant regardless of the position of the methyl group in the molecule

5 It might be thought that dilute emulsions would be ideal systems

6 It was considered that stabilizers belonged to a class of substances, which had been known

as “surface active agents”

7 In the early 1920’s it was reasoned in England that individual particles of latex would be vulcanized without breaking the emulsion

6.9 Translate into English

1 Như đã biết, đặc tính riêng biệt của nhũ tương điển hình là dạng hình cầu của hạt keo

2 Người ta đã biết rằng, đường kính của hạt nhũ tương phụ thuộc vào độ nhớt và sức căng bề mặt cũng như vào cường độ lắc

3 Người ta cho rằng, khi thêm vào một lượng nhỏ chất nhũ hóa thì có thể tăng tính ổn định của nhũ tương

4 Như đã biết, cho đến nay chưa có một lý thuyết định lượng phù hợp nào về độ bền của nhũ tương được đưa ra

5 Ý nghĩa thực tiễn của nhũ tương trong thực tế cũng như trong kỹ thuật là rất lớn

6 Những nhũ tương tổng hợp mà được điều chế từ những chất lỏng khác nhau có mặt chất nhũ hóa đặc biệt thì có ý nghĩa lớn

6.10 Write a short summary of the text

UNIT 7 PLASTICS IN THE CHEMICAL AGE

The plastics industry is typical of the industries that have developed in recent years as

a result of chemical research The chemist is a key man in the plastics industry, and it is from chemical laboratories that new plastics are appearing almost day by day

Little more than twenty years ago, plastics were still widely regarded as cheap substitutes for traditional materials such as wood and porcelain Today, plastics have established themselves as wonderful new materials in their own right They have ousted older materials because they can do a better job, often at lower cost

We find new plastics encroaching in the fields where metals have reigned supreme The development of new techniques, such as lamination, has shown how modern plastics may

be used for many engineering and structural applications We can make gears and bearings for heavy machinery from laminated plastics We can build car bodies, and the hulls of boats, we can pump our water supplier through the plastic pipes, and support larger buildings on plastic beams

In time we shall have seagoing ships with plastics used for almost everything from crockery on the tables to the hull itself We shall fly at supersonic speeds in plastic aircraft, and motor in cars with plastic bodies House and public buildings will be constructed from plastics panels supported by plastic beams We shall find plastic spaceships carrying us to the moon

As the demand for the plastics grows, the need for chemical raw materials will increase Plastics are largely organic chemicals, in which the “backbone" of the molecule consists of carbon atoms They are made from simpler organic chemicals in which the molecules contain fewer carbon atoms, which are manipulated by the plastics chemist into thread - like structures

Today, we draw our supplies of simple organic chemicals very largely from coal and petroleum These are the chemical residues of plants and animals that lived millions of years ago, and they contain a variety of different organic substances We obtain simple chemical raw materials from coal by heating it in retorts, and from petroleum by refining and processing techniques Coal and petroleum are capital assets; the world has a limited supply, and we cannot replace the materials we use As the demand for organic chemicals increases, the stocks of coal and petroleum will diminish; and some day, they will be gone

Before this happens, we shall have to seek new sources of organic chemical raw materials, and we shall find them in the carbon dioxide of the air This is the gas from which the growing plant builds up the sugar and other substances as organic raw materials, without waiting for nature to turn them into coal and oil

It seems likely that alcohol will become the most important chemical raw material of all as supplies of coal and petroleum dwindle We can make alcohol by fermentation of the sugar produced by fast growing plants, and it will provide us with the raw materials for

plastics and other synthetic chemical industries The tropical countries of the world will use their vast areas of land for the cultivation of sugar producing crops

It is probable, too, that we shall in time discover the secrets of photosynthesis, by which the plant uses sunshine to convert carbon dioxide into sugars and we shall use some synthetic process of this sort to turn carbon dioxide from the air into simple organic chemicals without depending entirely upon the growing plant to do it for us

The twentieth century is the time when man began to understand how to make all the new synthetic materials from simple chemicals; materials, such as fibers and rubbers, synthetic drugs and dyes, insecticide and weed killers, hormones and vitamins - and, of course plastics

Exercises 7.1 Read and translate into Vietnamese

Plastic, typical, recent, appear, substitute, traditional, wood, porcelain, ouster, encroaching, reign, supreme, lamination, gear, bearing, hull, boat, pump, supplier, pipe, seagoing, supersonic, panel, spaceship, backbone, manipulate, residue, animal, retort, asset, diminish, carbon dioxide, alcohol, dwindle, fermentation, cultivate, scops, secret, photosynthesis, entirely, fiber, rubber, drug, dye, insecticide, weed, killer, hormone, vitamin

7.2 Answer the following questions

1 What have plastics ousted today?

2 What can we make from laminated plastics?

3 Which ships will carry us to the moon?

4 What does the backbone of the molecule in plastics consist of?

5 What do we draw our supplies of? (today)

6 What do we obtain simple chemical raw materials from?

7 Why do we have to seek for new sources of organic chemical raw materials?

8 Where shall we find them?

9 What will become the most important chemical raw materials?

7.3 Read and translate the following derivatives

7.4 Translate into Vietnamese paying attention to the words in bold type

a)

1 Plastics can do a better job, often at lower cost

2 The development of lamination has shown how modern plastics may be used for many

engineering and structural applications

3 We are able to build car bodies and the hulls of the boats from plastics

4 We shall have to seek new sources of organic chemical raw materials

5 The twentieth century is the time when one has to understand how to make all the new

synthetic materials from simple chemicals

b)

6 In some time we shall have seagoing ships with plastics used for almost everything from

the crockery on the table to the hull itself

7 We used plastics as cheap substitutes for traditional materials such as wood and

porcelain

8 House constructed with the use of plastic parts is rather cheap

9 Houses and public buildings will be constructed from plastic panels supported by plastic

beams

10 He supported himself by working at a chemical plant

11 We can make alcohol by fermentation of the sugar produced by fast - growing plants

12 We produced a great variety of alcohol by fast - growing plants

7.5 Write a summary of the text and retell the text

7.6 Translate into English

1 Việc chế hóa các chất dẻo dạng lớp đã chỉ ra rằng chất dẻo có thể được sử dụng trong nhiều ngành kỹ thuật và trong xây dựng

2 Ngày nay chúng ta có thể làm máy bay bằng chất dẻo

3 Ngày nay, nguyên liệu để sản xuất chất dẻo là những chất hữu cơ thông thường lấy từ than

đá và dầu mỏ

4 Vì chúng ta có trữ lượng than và dầu mỏ hữu hạn nên chúng ta cần phải tìm kiếm những nguồn năng lượng mới

5 Có thể rượu sẽ trở thành một trong những nguồn nguyên liệu hóa học quan trọng nhất

6 Có thể chúng ta sẽ phát hiện được những bí mật của sự quang hợp để biến CO2 thành đường nhờ ánh sáng mặt trời

UNIT 8 ENZYMES

The study of enzymes is a subject, which has a special interest because it lies just on the borderline where the biological and the physical sciences meet On the other hand, enzymes are of supreme importance in biology Life depends on a complex network of chemical reactions brought by specific enzymes, and any modification of the enzyme pattern may have far- reaching consequences for the living organism On the other hand, enzymes, as catalyst, are receiving increasing attention from physical chemists

Enzymology has become a large and rapidly developing subject, which has close connections with many sciences, especially biochemistry, physical chemistry, bacteriology and microbiology, genetics, botany and agriculture, pharmacology and toxicology, pathology, physiology, medicine, and chemical engineering It has in addition important practical applications to activities as diverse as brewing and industrial fermentations, pest control, and chemical warfare

It is sometimes difficult to realize that enzymology is a subject of comparatively recent growth; the beginning of the subject can be traced back to the early nineteenth century, but the great developments have come during the last forty years

Scientists found that an alcohol precipitate of malt extract contained a thermolabile

substance, which converted starch into sugar This substance is now called “amylase"

The great increase in the knowledge of the enzymes of living matter has brought a greatly increased understanding of the mechanism of many of the most fundamental vital processes, especially of metabolic processes which lead to the production and utilization of energy, on which life depends

The availability of enzymes in the pure state has made possible their quantitative study

by physico - chemical methods

The substance on which an enzyme acts is termed the “substrate” of the enzyme

In many cases an additional substance besides the enzymes and substrate is required in order that the reaction may proceed Such “coenzymes” are part of the catalytic mechanism, and are found unchanged at the end of the reaction They are thus distinguished from substrates

It is frequently found that the addition of substances, which do not take part in the reaction, diminishes its velocity These substances are known as “inhibitors “ Many of these inhibitors act as poisons of particular enzymes, and in some cases in very small concentrations

Only comparatively recently has it been possible to develop the study of enzymes and enzyme systems in relation to the living cell

Exercises 8.1 Read and translate into Vietnamese

Enzyme, borderline, biological, supreme, modification, consequence, organism, attention, enzymology, biochemistry, bacteriology, genetic, botany, agriculture, pharmacology, toxicology, pathology, physiology, medicine, diverse, brew, fermentation, warfare, comparative, thermolabile, starch, amylase, vital metabolic, utilization, quantitative, substrate, act, coenzyme, distinguish, diminish, velocity, inhibitor, poison, living cell

8.2 Answer the following questions

1 Why has the study of enzymes a special interest?

2 What does life depend on?

3 What has enzymology close connections with?

4 What substance is called “amylase"?

5 What is termed the “substrate"?

8.4 Translate into Vietnamese paying attention to the words in bold type

1 The study of the enzymes is a subject, which has a special interest

2 The treatments to which enzymes can be subjected are limited by their instability

3 The path of energy migration is the subject of considerable controversy

4 When subjected to a deforming force rigid structure will often fracture

5 Only a comparatively recent has it been possible to systematically develop the enzyme

studies in relation to the living cell

6 In many cases an additional substance besides the enzyme and substrate is required

7 Enzymology has in addition important practical applications in brewing and industrial

fermentations, pest control and chemical warfare

8 It is frequently found that the addition of substances, which do not take part in the

reaction, diminishes its velocity

8.5 Translate into English

1 Việc nghiên cứu các ezym rất thú vị vì nó ở vào giao điểm của hai ngành khoa học: hóa học và sinh học

2 Sự sống phụ thuộc vào hàng loạt các phản ứng hóa học được thực hiện nhờ các ezym đặc biệt

3 Enzym học đã trở thành một ngành khoa học đang phát triển rất nhanh

4 Sự hiểu biết của chúng ta về enzym của cơ thể sống đã giúp chúng ta hiểu rõ hơn về cơ chế của nhiều quá trình cơ bản

5 Việc tách được các enzym ở dạng tinh khiết làm cho việc nghiên cứu các tính chất của enzym trở nên có thể thực hiện được

8.6 Speak of the importance of enzyme

I.2 ADDITIONAL UNITS

UNIT 9 PROPERTIES OF GELS

Structure The structure of various xerogels and jellies has been thoroughly studied in

the last decades by several methods, such as the X-ray method, observations in the ultramicroscope, studies with the electron microscope, and so on From all these studies the important conclusion may be drawn that jellies which contain large amounts of liquid have a network structure in which the liquid is bound to the fibrous particles and is also mechanically immobilised between them The less asymmetric are the colloidal particles, the higher must

be their concentration to be able to form a jelly

The shape of the colloidal particles, however, is not the only factor, which determines the ability to form stable jellies For instance, a 4% solution of nitrocellulose in a mixture of ether and alcohol does not set, although the molecules of the nitrocellulose are very long and thin Another important factor, which determines the gelation, is the possibility of entanglement of the fibres or rods The rods and fibres must be linked if a network is desired Hence the structural elements of a jel need not have long fibrous macromolecules The solid framework of a jelly may be composed also of plate or needle shaped crystals as micelles In such instances the concentration of the solid is always relatively high, whereas with linear macromolecules the concentration may be lower The framework of a jelly must be coherent

If the particles do not stick together there is no gelation For example, concentrated graphite dispersion does not conduct electricity in the fluid state, although it becomes a conductor after

it sets, because countless contact points are formed throughout the network All gels can be classified into three structural groups: 1) gels with unstable frameworks; 2) jellies with metastable frameworks, and 3) systems with stable networks A very labile framework is encountered in ferric hydroxide, aluminum hydroxide, bentonite, graphite and many other

gels in which the structural elements are not very asymmetric The crystallites or particles are

joined in such cases by very weak cohesive forces (van der Waals attraction) Such gels are often thixotropic, i.e the framework is so weak that it is destroyed by shaking To this group belong also the entanglement gels of linear macromolecules, such as unvulcanized or rubber polystyrene The corresponding solids, e.g polystyrene, when placed in liquid in which they can dissolve, will swell first and then slowly go into solution In the instances of weak frameworks of linear macromolecules the gels swell without limit; if the instance structural elements are not joined by sufficiently strong forces, the solvent may in time destroy the framework by gradually disconnecting the building units Metastable frameworks are encountered in most of the protein jellies, for in those of gelatin Finally, there are gels with stable frameworks, for example the gels of relatively concentrated silicic acid Such gels can

be obtained upon addition of acid to a solution of sodium silicate The resulting gel is rigid and stable, and it cannot be reversibly transformed into a liquid system

Exercises 9.1 Translate into Vietnamese

Gel, xerogel, microscope, ultramicroscope, jelly, network, fibrous, mechanical, immobilise, asymmetric, colloidal, gelation, entanglement, rod, macromolecules, needle shaped, micelle, conductor, countless, metastable, labile, crystallite, cohesive, thixotropic, entanglement, unvulcanize, rubber, swell, silicate, reverse, reversible, rigid, sodium

9.2 Answer the following questions

1 What methods has the structure of various xerogels and jellies been studied by?

2 What conclusion may be drawn from all these studies?

3 What factors determine the ability to form stable jellies?

4 What must be linked if a network is desired?

5 What may the solid framework of a jelly be composed of?

6 In what cases may the concentration be high and low?

7 Is there gelation when the particles do not stick together?

8 What groups can all gels be classified into?

9 What are metastable frameworks encountered in?

10 What examples of gels with stable frameworks can you give?

11 How can gels with stable frameworks be obtained?

9.3 Translate the following sentences paying attention to the words in bold type

1 The less asymmetric are the colloidal particles, the higher must be their concentration to

be able to form a jelly

2 The larger the viscosity, the larger will be the inefficient expenditure of energy

3 The smaller the number of valence electrons, the more readily the atom yields them

4 If the acid is nonvolatile, only the ammonia is driven off while the acid remains in the

vessel

5 The shape of the colloidal particles, is not the only factor, which determines the ability to

form stable jellies

6 Hence the structural elements of a jel need not have long fibrous macromolecules

9.4 Translate into Vietnamese paying attention to the Participles

1 Some adsorbents may contain sufficient acid or alkali to after the pH of the water being treated

2 Having been compressed the air is to be cooled

3 Having been composed of liquid particles emulsions disperse in other liquids

4 Being used in different fields of chemistry, industry and medicine colloid chemistry becomes increasingly important

5 When placed in a liquid, the corresponding solids will swell first and then slowly go into solution

9.5 Translate into English

1 Hạt keo có tính đối xứng càng thấp thì nồng độ của chúng phải càng cao

2 Hình dạng của hạt keo không phải là yếu tố độc nhất quyết định khả năng tạo thành keo bền

3 Nếu các hạt keo không dính vào nhau thì sự tạo gel không xảy ra

4 Một số gel thu được khi thêm axit vào dung dịch natri silicat Gel tạo thành như vậy thì rắn, bền vững và không thể chuyển thành trạng thái lỏng

9.6 Write an outline of the text and retell it

UNIT 10 SOLVENT PROPERTIES OF SURFACTANT SOLUTIONS

EMULTION POLYMERIZATION

The term “emulsion polymerization” is applied to a variety of processes which have in common that the main chemical reaction is a polymerization and that the end product is latex,

i e a suspension of polymer particles of colloidal dimensions in an aqueous medium Such a

process is called emulsion polymerization as the initial mixture of reagents usually consists of

an aqueous emulsion of monomer and small amounts of other chemicals Polymerizations in which the monomer is initially dissolved in water producing a suspension of small particles of polymer are sometimes named emulsion polymerizations as well, though rather inappropriately

If the product of a polymerization consists of a suspension of relatively large particles (dimensions ~ 1), the process is termed a suspension polymerization The difference

between suspension and emulsion polymerization points to a process of formation of particles

in the latter, whereas no such process occurs in suspension polymerization In fact, suspension polymerizations were found to show the characteristics of a polymerization reaction in bulk monomer, the aqueous phase playing only a minor role

In 1926 German scientists succeeded in producing synthetic rubber latices by polymerizing monomer emulsions stabilized by various surf active agents The addition of surfactants profoundly influences the course of polymerization In 1938 Fikentscher was the first to express the view that in emulsion polymerization the monomer, dissolved in the aqueous phase polymerizes rather than the monomer present as emulsified droplets

A great deal of knowledge has been gained since emulsion polymers were first produced on a large scale Smith and Ewart have developed a quantitative theory of particle formation and treated the growth of the particles during polymerization One of the growth mechanisms considered has been found to hold true in many polymerizations with small particles

The chemical reactions of emulsion polymerization take place in heterogeneous systems in which polymer particles of colloidal dimensions are formed Physical and chemical phenomena influence each other profoundly

The extensive data obtained in emulsion polymerization of methyl methacrylate are in good agreement with the assumption that the rate of reaction at high conversion is governed only by the diffusion rate of the monomer and the radical end of the polymeric chains

Exercises 10.1 Translate into Vietnamese

Term, emulsion, polymerization, emulsion polymerization, latex, suspension, colloid, initial, inappropriate, suspension, suspension polymerization, characteristic, latice, stabilize,

surfactive, surfactant, profound, express, polymerise, droplet, quantitative, phenomena, assumption, govern, diffusion, radical, chain.

10.2 Answer the following questions

1 What is meant under “emulsion polymerization”?

2 What is meant under “suspension polymerization”?

3 What is the difference between emulsion and suspension polymerization?

4 Who treated the problem of the particle growth during polymerization?

5 What are the dimensions of the particles formed during emulsion polymerization?

10.3 Give a summary of the text

10.4 Give Vietnamese equivalent to

10.5 Translate into English

1 Mủ (latex) là sản phẩm cuối cùng của sự polyme hoá nhũ tương

2 Phản ứng hoá học của sự polyme hoá nhũ tương xảy ra trong hệ dị thể và được kết thúc bởi

sự tạo thành những hạt polyme có kích thước hạt keo

3.Khi nghiên cứu sự polyme hoá metyl metacrylat, các nhà khoa học đã thu được các dữ kiện đáng chú ý

4 Người ta đã xác nhận rằng poly metyl metacrylat thu được bằng cách polyme hoá nhũ tương thì rất cứng

UNIT 11 THE NATURE OF RUBBER - LIKE ELASTICITY

The characteristic property of rubber, its extensibility and complete recovery after even very large deformations, is shown also by many other substances Of these we may mention supercooled molten sulfur and selenium, gelatin, muscle fibrils, substances built from long chain molecules such as polyvinyl alcohol, etc These substances are very different chemically, but their common feature is a long flexible molecule There is a rubber- like state, which many substances made from long molecules, may assume under suitable conditions

The two factors which are necessary if perfect rubber - like elasticity is to be obtained are, firstly, that whole molecules must not be able to slip past each other under the action of deforming forces, and, secondly, that these forces shall meet little resistance in straightening out the coiled molecular chains In lightly vulcanized rubber, the long chains are connected across at certain points by the strong sulfur linkages This presence of only a few such points

of linkage is sufficient to prevent slipping of the whole molecules, which would result in plastic flow The atoms of the molecule share in the general thermal motion at any temperature, so that the free molecules would be continually coiling, twisting, and changing its shape There are many more ways in which such molecules can be arranged to give a crumpled chain

The lengths of chain between sulfur crosslinks behave in essentially the same way as the free rubber molecule, so that the vast majority of them are in a contracted form, which changes momentarily with the thermal motion This freedom comes from weakness of the Van der Waals forces between the chains, which are not strong enough to hold them permanently in position side by side

When we apply a force to the rubber, the flexible chains are slightly straightened, but are always attempting to return to their folded condition It is evident that, the more violent the thermal motion, the greater the tendency of the chains to return to their normal positions

If a rubber band is stretched by means of a weight, it contracts on heating owing to the effect

of the increased thermal motion This is contrary to the behaviour of normal substances, which deform more easily at high temperatures

The highly coiled and folded condition of the rubber chains permits their being extended up to seven times their original length Long before this, however, some of the chains will have been pulled approximately parallel When this occurs, the attractive forces between them become sufficiently strong to bind them together in a regular arrangement Thus the rubber is crystallized by tension This result was clearly demonstrated

by Katz using X - ray diffraction to detect the crystallinity He showed that ordinary, unstretched rubber has a disordered structure, resembling that of a liquid Sufficient stretching gives an X - ray diffraction picture similar to that shown by fibrous materials If the rubber is cooled, while under tension, to a low temperature, it does not contract when the tension is removed, and still gives a crystalline X - ray diffraction pattern On reheating, “melting

“occurs and the rubber contracts If the frozen stretched rubber is pulverized when cold, it splits up into fibrous pieces, owing to the parallel orientation of the chains