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6 days ago This wikiHow teaches you how to download eBooks from your Google Play Books library. You can use the Google Play Books website to do. To download from Wiley Online Library: Search or browse for the ebook you want . Ebooks available for download have the open lock icon. Phần 3: Bài tập - gồm một số bài tập để luyện cách phát âm, cách đọc các từ viết tắt, . Exercise 1 - 33 tetraedge.info 5 Table of Elements Các nhà máy có thể dùng tàu hỏa, xe tải, xe kéo để vận chuyển mía tới. 2.


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20 Tháng Mười Hai #3 Tạo Ebook PRC:Hướng dẫn làm EBOOK từ FILE HTML tải . truy cập trang tetraedge.info và chọn một truyện để đọc bất kỳ, sau đó sao chép. Bạn có thể tải miễn phí tất cả các bài học Effortless English của tiến sĩ AJ Hoge. trình học và tài liệu hướng dẫn bao gồm các file Audio, Video và Ebook. bạn học viên đăng ký mua khóa học của tetraedge.info sẽ vẫn có thêm theo phương pháp Effortless English một cách dễ dàng hơn, hiệu quả hơn. You can easily download one, selected, or all chapters from a Book on tetraedge.info Follow the steps below and share with your patrons to be sure they.

Skip to main content. Log In Sign Up. Linh Le. Chemistry and Its Branches 8 Unit 2: Hydrogen 10 Unit 3: Water 12 Unit 4:

Types of Reactors 32 Unit Inventories 36 Unit The Laboratory Notebook 37 Unit Study Outline of Chemistry 40 Unit Sewage Treatment 44 Unit Safety in the Laboratory 47 Unit Chemical Engineering 48 Unit Gas Manufacture 50 Unit Sulfuric Acid 52 Unit Glass 54 Unit Rapid method of Determination of Potassium in Minerals 56 Unit The use of Radioactive Elements as Tracers 58 Unit Acetone 60 Unit Acetic acid 62 Unit M- Bromonitrobenzene 64 Unit Synthetic Rubber 66 Unit Classification of Fuels 68 Unit Petroleum 70 Unit Main Biological Molecules 72 Unit Study Outline of Microorganisms 75 Unit Food Manufacture and Nutrition 80 Unit The Importance of Biotechnology 85 Unit Bioreactor 92 Unit Ethyl Alcohol 95 Unit Distillation 97 Unit Beer and Ale 99 Unit Post-harvest System http: Processing Techniques and Equipment Unit Introduction to Biscuit - Making Unit Vegetable Processing Unit Introduction to Food Safety Unit Methods of Oil Extraction and Processing Unit Tea, Coffee and Cocoa Unit Meat and Fish Products Unit Traditional Fermented Milk Products Unit Plant and Animal Cell Cultures Unit Antibiotics Unit Single-Cell Protein: Production, Modification and Utilization Unit Immobilization of Enzyme and Cells Unit Biologica Regulation and Process Control Unit Abbreviation II.

Reading chemical and mathematical signs and Formulas III. There is; there are XXI. The study of chemistry may be divided into the following branches: Although chemistry is a very large and complex subject, which still continues to grow as new elements are discovered or made, new compounds are synthesized, and new principles are formulated.

The chemists or chemical engineers need to have some knowledge of all its branches, even if he may be specialized in a particular line. Chemistry science cannot do without physics and mathematics, and is also closely linked to some other sciences, e.

Read and translate into Vietnamese substances, reaction, chemistry, analysis, method, determination, material, inorganic, element, compound, organic, biochemistry, organism, molecular, radioactive, nuclei, industrial, atom, processes, synthesized, engineer, specialized, particular, accurate, mathematics, closely, geology, mineralogy, metallurgy, comprise, biology, concerned, knowledge, continue, sample B.

Answer the following questions 1. Give the definition of chemistry. Which are the main branches of chemistry? What is the difference between qualitative and quantitative analysis? What is the difference between inorganic and organic chemistry? What does physical chemistry study? What does structural chemistry deal with? What is radiochemistry? Which branches of chemistry are you interested in?

Is it necessary for you to have some knowledge of all branches of chemistry? Can chemistry as a science do without physics and mathematics? Translate into English 1. Its most important compound is water, H2O. Hydrogen is found in most of substances, which constitute living matter: It occurs in petroleum, petrol, and other hydrocarbon mixtures. It is also contained in all acids and alkalis. There are more compounds of hydrogen known than of any other element.

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Pure hydrogen is a colorless, odorless, tasteless gas. It does not support respiration, but is not poisonous. Hydrogen is a good conductor of heat as compared with other gases. Its specific heat is also higher than most other gases.

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Hydrogen is a combustible gas, burning in air or oxygen with a nearly colorless flame to form water vapor. Hydrogen also readily combines with fluorine and chlorine, less readily with bromine, iodine, sulfur, phosphorus, nitrogen, and carbon. The element is made commercially by the electrolysis of water, and is used in large quantities in the manufacture of ammonia, in the hydrogenation of liquid fats to form solid fats, and in the production of high temperatures.

In the laboratory hydrogen may be easily prepared by the reaction of an acid as sulfuric acid, with a metal such as zinc: Thus sodium and potassium react with cold water, producing sodium hydroxide and hydrogen. Boiling water may be readily decomposed by ordinary magnesium powder, while steam is decomposed by heated magnesium, zinc, iron, cobalt, lead, tin, and nickel, but not by silver or copper.

Hydrogen is evolved by the action of zinc, magnesium and iron on dilute hydrochloric and sulfuric acid on aluminum and tin. A solution of caustic soda or potash readily dissolves zinc or aluminum on warming, with evolution of hydrogen and formation of a soluble zincate or aluminate.

Read and translate into Vietnamese hydrogen, periodic, distributed, water, constitute, proteins, petroleum, petrol, hydrocarbon, alkalis, gases, density, combustible, oxygen, vapor, readily, combine, fluorine, chlorine, bromine, iodine, nitrogen, sulfur, electrolysis, ammonia, hydrogenation, liquid, production, laboratory, sulfuric acid, zinc, sodium, potassium, hydroxide, decompose, magnesium, iron, cobalt, lead, tin, nickel, copper, dilute, concentrated, hydrochloric acid, aluminum, solution, caustic, potash, dissolve, evolution, soluble, zincate, aluminate.

Where does hydrogen occur? What are the properties of hydrogen? How can hydrogen be prepared? What are its uses? Say a few sentences about hydrogen. It is the chief constituent of living matter. Its physical properties are strikingly different from those of other substances. Ordinary water is impure, it usually contains dissolved salts and dissolved gases, and sometimes organic matter.

For chemical work water is purified by distillation. Pure tin vessels and pipes are often used for storing and transporting distilled water. Glass vessels are not satisfactory, because the alkaline constituents of glass slowly dissolve in water. Distilling apparatus and vessels made of fused silica are used in making very pure water.

The impurity, which is hardest to keep out of water, is carbon dioxide, which dissolves readily from the air. The physical properties of water. Water is a clear, transparent liquid, colorless in thin layers. Thick layers of water have a bluish-green color. Pure water freezes at 0oC, and boils at oC. These temperatures are means of identifying water, for no other substance has these freezing and boiling points. The physical properties of water are used to define many physical constants and units.

A similar relation holds in the English system: Steam and ice Steam is water in the gaseous state. A cubic inch of water gives about a cubic foot of steam. When gaseous water is mixed with other gases, as in the air, we speak of it as water vapor; when unmixed, we call it steam.

Water may exist as steam at temperature lower than oC, provided the pressure is less than the usual atmospheric pressure of 15 pounds per square inch. If water is cooled sufficiently, it solidifies at 00C to ice.

There is considerable expansion during the solidification, and consequently ice is lighter than an equal volume of water. If we apply heat to ice, it melts. The water that runs off the melting ice is at a temperature of 00C, the same temperature as the ice. Read and translate into Vietnamese constituent, properties, strikingly, ordinary, impure, contain, purified, distillation, pure, vessel, pipe, distilled, alkaline, apparatus, fused, silica, impurity, carbon dioxide, air, transparent, bluish-green, identify, temperature, define, unit, weigh, approximately, ounce, gaseous, cubic, inch, pressure, atmospheric, square, sufficiently, equal, volume, ice, steam.

Why is water important to a human beings? What are the characteristic properties of water? Are glass vessels satisfactory for storing and transporting distilled water? Where does carbon dioxide readily dissolve from? What is the color of water? How is the unit of mass in the metric system chosen?

What is steam? What is the difference between steam and vapor? What is ice? The characteristic feature of gas is that its molecules are not held together, but move about freely. Because of this freedom of molecular motion a gas does not possess either definite shape or definite size, it shapes itself to its container. A liquid, on the other hand, has a definite volume, but does not have a definite shape. Only a solid is characterized both by a definite shape and definite size.

All substances can be divided into two classes: An elementary substance is a substance, which consists of atoms of only one kind, a compound is a substance which consists of atoms of two or more different kinds.

These atoms of two or more different kinds must be present in a definite numerical ratio since substances are defined as having a definite invariant composition.

Thus an elementary substance is composed of two or more elements. By this expression we mean an atom whose nucleus has a given electrical charge.

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The ingredients of a mixture are called its component. Sometimes a mixture consisting mainly of one component, with much smaller amounts of others, is called an impure substance.

The components present in the smaller amounts are called impurities. Read and translate into Vietnamese distinguished, aggregation, basis, characteristic, molecule, motion, possess, definite, container, characterized, essentially, actually, mixture, elementary, consist, numerical, ratio, invariant, composition, compose, confusion, expression, nucleus, electrical charge, equal, integral, integer, electron, changed, sign, relation, atomic, refer, homogeneous, exhibit, uniform, heterogeneous, aggregate, ingredient, component, amount.

Which are the three physical states? Give the characteristic features of a gas, a liquid, and a solid. What is a substance in chemistry? What is the difference between an element and a compound?

What is the mixture? Say a few sentences about the classification of matter. SOLUTIONS If sugar and water, two pure substances, are mixed together, a solution result, uniform throughout in its properties, in which the sugar can neither be seen with a microscope nor filtered out.

It is not distinguishable from a pure substance in appearance. However, when both are volatile the matter is not quite so simple and it is necessary to find out whether any change in composition and hence in properties occurs during a change in state.

Suppose we wish to determine whether air is a pure substance or a solution. One method would be to liquefy a certain amount and then observe what happens to it as it slowly evaporates. As the evaporation proceeds one may observe that a- The light blue color gradually becomes deeper b- The temperature of the liquid slowly rises c- The densities of both liquid and gas change.

Any one of these as well as other possible observations show that air must contain two or more components whose relative amounts change during the evaporation, causing the observed changes in properties due to differences between the components in color, volatility, density, chemical behavior. Still other properties might have been used. The term solution is not restricted to liquid solutions.

All gases are completely miscible with each other, forming but one phase, so that every mixture of gases is a solution. If liquid air is distilled in a scientifically constructed still, it is possible to separate it into two nearly pure constituents.

One of these constituents, nitrogen, is found to be slightly lighter than air; it can be condensed to a colorless liquid boiling at C; it is very inert chemically, reacting with but few other substances. The other constituent, oxygen, is slightly heavier than air; it gives, when condensed at low temperatures, a blue liquid boiling at As another illustration, suppose we have a solid metal, which appears to be perfectly homogeneous under the microscope.

We could determine whether it is a solution or a pure substance by melting it, dipping into the melt a suitable thermometer and letting it cool slowly, taking temperature readings at regular intervals, and plotting temperature against time. Read and translate into Vietnamese result, throughout, microscope, appearance, experimental, distinction, solute, volatile, solvent, evaporated, matter, occur, determine, liquefy, observe, evaporation, proceed, gradually, observation, relative, cause, changes, volatility, behavior, restricted, miscible, completely, phase, alloy, metal, continuously, solid, scientifically, constructed, separated, condensed inert, react, illustration, suppose, appear, perfectly, suitable, thermometer, interval.

What is a solution? Is it distinguishable from a pure substance in appearance?

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When is the experimental distinction between a pure substance and a solution simple? What is the difference between a solute and a solvent? How can you determine whether air is a pure substance or a solution?

Is the term solution restricted only to liquid solutions? What does it mean when a substance is volatile? Give the constituents of air and compare them with each other. Give some liquids that are miscible. Give some examples of solids soluble in liquids. UNIT 6: Some substances occur very nearly pure in nature, but most materials are mixtures, which must be separated or purified if pure substances are desired, and most manufactured materials also require purification.

The separation of two different phases is often rather easy. Particles of a solid phase mixed with a liquid phase may be separated from the liquid by filtration.

The precipitate is removed by pouring the mixture on a folded filter paper in a funnel. Ordinary filter paper contains pores about 0. A precipitate may also be removed by letting the suspension stand quietly until the precipitate has settled to the bottom of the container under the influence of gravity. The supernatant liquid can then be poured off. This process of pouring off is called decantation.

The process of settling can be accelerated by the use of centrifugal force, in a centrifuge. Ordinary centrifuges produce forces of the order of or 1, times that of gravity. Supercentrifuges have been built which give forces over , times as great as that of gravity. Two liquid phases may be conveniently separated by use of a special device, the separatory funnel. A dropper may also be used for this purpose. An impure substance may often be purified by fractional freezing.

The impure liquid substance is cooled until part of it has crystallized, and the remaining liquid, which usually contains most of the impurities, is then poured off, leaving the purified crystals. A liquid can be purified by distillation in a still. The liquid is boiled in a flask or some other container, and the vapor is condenser, forming a liquid distillate, which is collected in a receiver.

Stills so special design have been invented, which are very effective in separating liquid mixtures into their components. Read and translate into Vietnamese isolation, purification, include, technique, desire, manufacture, require, separation, particle, filtration, precipitate, removed, pour, funnel, filtrate, residue, retained, pore, diameter, suspension, influence, gravity, supernatant, decantation, accelerated, use, used, centrifugal, centrifuge, produce, conveniently, device, separatory, purpose, fractional, crystallized, crystal, distillation, condenser, distillate, collected, receiver, design, effective B.

Which methods can be used for purifying substances? What is decantation? How can the process of settling be accelerated? What is a separatory funnel used for? What does a still consist of? Say a few sentences about the isolation and purification of substances. UNIT 7: Reactions between ions in solution without change in oxidation state are usually extremely fast. An example is the neutralization of an acid by a base, which proceeds as fast as the solutions can be mixed.

Presumable nearly every time a hydronium ion collides with a hydroxide ion reaction occurs, and the number of collisions is very great, so that there is little delay in the reaction. The formation of a precipitate, such as that of silver chloride when a solution containing silver ion is mixed with a solution containing chloride ion, may require a few seconds, to permit the ions to diffuse together to form the crystalline grains of the precipitate. On the other hand, ionic oxidation-reduction reactions are sometimes very slow.

An example is the oxidation of stannous ion by ferric ion. This reaction does not occur every time a stannous ion collides with one or two ferric ions. In order for the reaction to take place, the collision must be of such a nature that electrons can be transferred from one ion to another, and collisions, which permit this electron transfer to occur, may be rare.

The factors, which determine the rate of a reaction, are manifold. Most actual chemical processes are very complicated, and the analysis of their rate is very difficult. As reaction proceeds the reacting substances are used up and new ones are formed; the temperature of the system is changed by the heat evolved or absorbed by the reaction; and other effects may occur which influence the reaction in a complex way.

For example, when a drop of a solution of potassium permanganate is added to a solution containing hydrogen peroxide and sulfuric acid no detectable reaction may occur for several minutes. The reaction speeds up, and finally the rate may become so great as to decolorize a steady steam of permanganate solution as rapidly as it is poured into the reducing solution. This effect of the speeding up of the reaction is due to the vigorous catalytic action of the products of permanganate ion reduction: Read and translate into Vietnamese require, completion, oxidation, extremely, neutralization, base, presumably, nearly, hydronium ions, collide, collision, delay, formation, chloride, permit, diffuse, crystalline, reduction, oxidation, stannous, transfer, manifold, depend, intimacy, concentration, reactant, circumstances, irradiation, ultraviolet, neutron, affect, effect, catalyst, evolved, absorbed, permanganate, detectable, decolorize, reduce, vigorous, product.

What is meant by the rate of a chemical reaction? Name some factors affecting the rate of a chemical reaction. What is the effect of temperature and pressure on reaction rate? What is the function of catalysts? What is the rate of complicated chemical processes? Say a few sentences about the rate of chemical reactions. UNIT 8: The simplest hydrocarbon is methane, CH4.

Its molecules are tetrahedral, the four hydrogen atoms lying at the corners of a regular tetrahedron around the carbon atom, and connected with the carbon atom with single bonds. Methane is a gas, which occurs in natural gas, and is used as a fuel.

It is also used in large quantities for the manufacture of carbon black, by combustion with a limited supply of air. The hydrogen burn to water, and the carbon is deposited as very finely divided carbon, which finds extensive use as filler for rubber for automobile tires.

The compounds of this series are not very reactive chemically. They occur in complex mixtures called petroleum. The molecules heavier than ethane are characterized by containing carbon atoms attached to one another by single bonds.

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The lighter members of the paraffin series are gases, the intermediate members are liquids, and the heavier members are solid or semi-solid substances.

Gasoline is the heptane-nonane mixture, and kerosene the decane-hexadecane mixture. Heavy fuel oil is a mixture of paraffins containing twenty or more atoms per molecule.

The lubricating oils and solid paraffin are mixtures of still larger paraffin molecules. The substance ethylene, C2H4, consists of molecules in which there is a double bond between the two carbon atoms.

This double bond confers upon the molecule the property of much greater chemical reactivity than is possessed by the paraffins. Because of this property of readily combining with other substances, ethylene and related hydrocarbons are said to be unsaturated.

Acetylene is the first member of a series of hydrocarbons containing triple bonds. Aside from acetylene, these substances have not found wide use, except for the manufacture of other chemicals.

The hydrocarbons, the molecules of which contain a ring of carbon atoms, are called cyclic hydrocarbons. Cyclohexane, C6H12, is representative of this class of substances. It is a volatile liquid, closely similar to normal hexane in its properties.

Another important hydrocarbon is benzene, having the formula C6H6. For many years there was discussion about the structure of the benzene molecule.

August Kekule suggested that the six carbon atoms are in the form of a ring, and this has been verified: Kekule suggested that, in order for a carbon atom to show its normal quadrivalence, the ring contains three single bonds and three double bonds in alternate positions.

Other hydrocarbons, derivatives of benzene, can be obtained by replacing the hydrogen atoms by methyl groups or similar groups. Benzene and its derivatives are used in the manufacture of drugs, explosives, photographic developers, plastics, synthetic dyes, and many other substances. Read and translate into Vietnamese methane, tetrahedral, tetrahedron, bond, nature, natural, fuel, combustion, supply, deposited, extensive, series, formula, petroleum, ethane, intermediate, gasoline, kerosene, lubricating, ethylene, double, confer, reactivity, paraffin, unsaturated, acetylene, triple, cyclic, representative, hexane, benzene, aromatic, odor, discussion, structure, suggest, ring, verify, diffraction, planar, hexagon, quadrivalence, alternate, position, derivative, replace, methyl, explosives, developer, plastics, synthetic, dye.

What kinds of substances are hydrocarbons? What is methane and what are its uses? What is the difference between petroleum and petrol? What is ethylene? What is acetylene? Which hydrocarbons are called cyclic hydrocarbons? What is the representative of cyclic hydrocarbon class of substances?

What is benzene? What did August Kekule suggest? What are the uses of benzene? UNIT 9: The equipment of a chemical laboratory varies according to the nature of the work, which is to be carried out. Every chemical laboratory should be provided with running water, gas and electricity. The water supply is conducted from the mains by means of pipes, the piping terminating in taps under, which there are sinks to take away waste water and other non-objectionable liquids.

When one needs water one turns the tap on and stops it flowing by turning the tap off. Similarly a system of pipes is attached to the gas main from where gas reaches the various kinds of burners. They serve for producing flames of different intensity, the Bunsen burner being the most common type used.

Apart from a gas supply there is electricity which serves for lighting and as a driving power. For operating electricity, switches or switch buttons are employed. That is why we talk about switching on the light or switching it off.

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One of them, a desiccator, is used for drying materials. Ovens, furnaces or kilns serve for generating high temperatures. Where harmful vapors and undesirable odorous develop during the operation, a hood with suitable ventilation has to be provided for their escape. Of primary importance are glass and porcelain vessels. Glass vessels for chemical processes are made of special materials. They have to resist sudden changes in temperature, to withstand very high temperature: The necessary assortment of laboratory glassware includes test tubes, beakers, various flasks, watch glasses, funnels, bottles, and cylinders.

Porcelain articles consist of various kinds of dishes, basins and crucibles of various diameters. A grinding mortar with a pestle, desiccating dishes and stirrers are also generally made of porcelain.

Containers made of them are especially suitable for storing stock solutions. The analytical balance, which is used for accurate weighing of samples, is usually kept in a separate room. Read and translate into Vietnamese indispensable, research, institute, confirm, demonstrate, phenomena, industry, application, science, equipment, vary, theoretical, technician, technologist, verify, employ, scientist, scientific, electricity, terminate, attached, burner, intensity, power, powder, equipped, variety, desiccator, oven, furnaces, generate, porcelain, refractory, assortment, cylinder, basin, crucible, pestle, stirrer, increase, resistant, unbreakable, analytical, balance, polyethylene.

What is the task of laboratory work? Why is it important and necessary for you as students of chemistry to make experiments in your school laboratories? Describe the general equipment of chemical laboratories.

Which properties should the glass be used for making chemical vessels possess? What does the necessary assortment of laboratory glassware include? What do porcelain articles usually consist of?

What are the advantages of polyethylene bottles? What are containers made of plastic materials especially suitable for? What do burners serve for? What is the analytical balance used for? Elements already known retained their old names, e.

The names of compounds are formed from those of their components so as to indicate their composition. When a metal forms two compounds with oxygen, the two oxides are distinguished by adding -ous and -ic to the Latin name of the metal, signifying the lower and higher oxidation states respectively, e.

The salts corresponding to cuprous oxide are called cuprous salts, e. Another way of distinguishing between different compounds of the same element is by the use of the Greek prefixes to the names of the elements. These prefixes are as follows: To these we may add the Latin hemi-, meaning one half, and sesqui-, meaning one and a half, and per-.

By the use of these prefixes we can designate the compounds more precisely than by means of the prefixes -ous and -ic, especially when more than two compounds exist. Oxides, which form salts with acids, are known as basic oxides; by combination with water, basic oxides form bases. H2O are ferrous hydroxide and ferric hydroxide, respectively.

The endings -ous, -ic are also applied to acids, the -ous acid containing less oxygen than the -ic acid, e.

Salts are named in relation to the acids from which they are derived according to the following rules: Accordingly, salts of sulfurous acid are called sulfites, those of sulfuric acid, sulfates. Salts of phosphorous acid are phosphites, of phosphoric acid, phosphates, etc. Read and translate into Vietnamese nomenclature, devised, binary, sodium chloride, respectively, designate, basic, bases, hydroxyl, formulas, salt, corresponding, sodium chlorite, cuprous oxide, cupric oxide, sodium chlorate, involve.

When was the systematic chemical Nomenclature devised and what is the difference between the names of elements already known at that time and the names of newly discovered elements? How are the names of compounds formed? What are the endings -ous, -ic used for and what is the difference between them?

When are the Greek prefixes mono-, di-, tri-, etc. What are the rules for forming the names of salts? Certainly, all our natural rivers and lakes and even the water stored in most reservoirs may be subjected to pollution, and generally cannot be considered safe for drinking purposes without some forms of treatment.

The type and extent of treatment will vary from city to city, depending upon the conditions of the raw water. Treatment may comprise various processes used separately or in combinations, such as storage, aeration, sedimentation, coagulation, rapid or slow sand filtration, and chlorination, or other accepted forms of disinfection.

When surface waters serve as a municipal water supply, it is generally necessary to remove suspended solid, which can be accomplished either by plain sedimentation or sedimentation following the addition of coagulating chemicals. In the water from most streams that are suitable as a source of supply, the sediment is principally inorganic, consisting of particles of sand and clay and small amount of organic matter.

In this water there will also be varying numbers of bacteria, depending upon the amount of bacteria nutrients, coming from sewage or other sources of organic matter, and upon the prevailing temperature. Many of the bacteria may have come from the soil and, as a result, during a season of high turbidity when there is a large amount of eroded soil in the water, the bacterial count from this source may be relatively high.

If the organisms are derived from sewage pollution, the number will be highest during periods of low flow when there is less dilution, and at this time the turbidity will, in general, be low. The amount of sediment may vary a great deal from one river to another, depending upon the geological character of the various parts of the drainage system. The size of the suspended particles can also vary greatly. In some waters the clay particles may be extremely fine, in fact, they may be smaller than bacteria.

The time required for satisfactory sedimentation differs for different waters, and generally must be established by actual experiments. Some waters can be clarified satisfactorily in a few days, while others may require weeks or months. As far as total weight of sediment is concerned, the bulk of it is probably removed in a few days, but this may not bring about a corresponding change in the appearance of the water, since the smaller particles may have greater influence than the large ones upon the apparent color and turbidity.

When plain sedimentation is used primarily as a preliminary treatment, a high degree of clarification is not needed and, as a result, shorter periods of settling are adequate. After flocculation treatment, water is passed through beds of sand with diatomaceous earth to accomplish sand filtration. As we mentioned previously, some protozoan cysts, such as those of G. The microorganisms are trapped mostly by surface adsorption in the sand beds. They do not penetrate the tortuous routing of the sand beds, even through the openings might be larger than the organisms that are filtered out.

These sand filters are periodically backflushed to clear them of accumulations. Water systems of cities that have an exceptional concern for toxic chemicals supplement sand filtration with filters of activated charcoal carbon. Charcoal has the advantage of removing not only particulate matter but also some dissolved organic chemical pollutants. Before entering the municipal distribution system, the filtered water is chlorinated. Because organic matter neutralized chlorine, the plant operators must pay constant attention to maintaining effective levels of chlorine.

There has been some concern that chlorine itself might be a health hazard, that it might react with organic contaminants of the water to form carcinogenic compounds. At present, this possibility is considered minor when compared with the proven usefulness of chlorination of water. One substitute for chlorination is ozone treatment. Ozone O3 is a highly reactive form of oxygen that is formed by electrical spark discharges and ultraviolet light. The fresh odor of air following an electrical storm or around an ultraviolet light bulb is from ozone.

Ozone for water treatment is generated electrically at the site of treatment. Use of ultraviolet light is also a possible alternative to chemical disinfection. Arrays of ultraviolet tube lamps are arranged in quartz tubes so that water flows close to the lamps. This is necessary because of the low penetrating power of ultraviolet radiation.

Read and translate into Vietnamese treatment, combination, storage, aeration, sedimentation, coagulation, chlorination, disinfection, bacterium, nutrients, sewage, pollution, beds of sand, drainage, influence, turbidity, diatomaceous earth, accumulation, activated carbon.

What are the various processes for water treatment? What is the method for removing the suspended solids from surface waters? What are the principal sediments from water of streams? What are the methods for trapping the microorganisms from various kinds of water?

What is the purpose of chlorination of water? What is the substitute for chlorination of water? What is the kind of physical agent for water treatment of microorganisms in Vietnam?

Say a few words about the water treatment in Vietnam. UNIT It should have a number of accessories in order to operate satisfactorily. First of all it generally must be closed, except for a vent, in order to prevent loss of material and danger to the operating personnel.

For reactions carried out under pressure the vent is replaced by a safety valve. High-pressure conditions frequently introduce complications in the design and greatly increase the initial cost. For example, the top closure must be able to withstand the same maximum pressure as the rest of the autoclave. At medium pressures a satisfactory closure can be assembled. It is usually necessary to agitate the reaction mixture in batch systems. This can be done mechanically with stirrers operated by a shaft extending through the reactor wall.

Provision for heating or cooling the reaction contents is often required. This may be accomplished by circulating a fluid through a jacket surrounding the reactor. Where heat effects are large enough to require the most rapid heat transfer, the jacket may be augmented by heating or cooling coils immersed in the reaction mixture.

Flow reactors. Flow reactors may be constructed in a number of ways. The conventional thermal- cracking units in the petroleum industry are examples of a noncatalytic type. The gas oil or other petroleum fraction is passed through a number of alloy-steel tubes placed in a series on the walls and roof of the furnace. On the other hand, flow reactors may consist of a tank or kettle, much like a batch reactor, with provision for continuously adding reactants and withdraw product.

From a design viewpoint the essential difference between tubular and tank reactors lies in the degree of mixing obtained.

In the tubular type, where the length is generally large with respect to the tube diameter, the forced velocity in the direction of flow is sufficient to retard mixing in the axial direction. On the other hand, in tank reactors, it is possible to obtain essentially complete mixing by mechanical agitation. Under these conditions the composition, temperature and pressure are uniform through the vessel.

Read and translate into Vietnamese kettle, tank, accessories, autoclave, agitate, mixture, stirrers, circulating, jacket, coils, petroleum, roof, furnace, endothermic, batch reactor, tubular, velocity http: What are the various kind of batch reactors? Why must the batch reactors be closed? Why does the top closure of batch reactors have to be installed with the vent or the safety valve? What is the purpose of a jacket surrounding the reactor? Tell something about the flow reactor? It is common practice, however, to regard it as consisting of two parts: Chemicals of this type are chiefly used in the manufacture of other products and do not ordinarily take the form of familiar household products or articles of commerce.

The chemical-process industry is even more dependent upon classifications of an arbitrary nature, and hence its scope is correspondingly more open to differences of opinion.

According to the most widely accepted definition, the chemical-process industry consist of the companies which manufacture such products as drug, soap, paint, fertilizers, vegetable and animal oils, and a number of various related products.

Contrary to more technically based definitions, however, this classification excludes companies engaged in the production of iron and steel, in petroleum refining, and in the manufacture of pulp and paper, rubber products, leather products and glass.

Their exclusion has probably been due primarily to the combination of their origin, large size, simple product structure, and well-defined markets. Hence, it has long been the custom of economists and statisticians to regard them as independent industries.

As matter of fact, both the oil industry and the steel industry were, until comparatively recently, much larger in size than the chemical industry as officially defined. Regardless of the arbitrary limitations of its official definition, however, the chemical industry has been steadily expanding. It has ignored industrial boundaries in the application of new manufacturing processes and in the development of new products. The already existing chemical companies have entered new industries, such as textiles, building materials, and drugs.

And industries not recognized as chemical in nature have begun the manufacture of chemical products by new methods from new materials. A recent and conspicuous example of this latter type of chemical expansion has been the development of the so-called "petrochemical industry", in which chemical products are manufactured from petroleum raw materials.

Read and translate into Vietnamese http: Is there any sharply defined frontier between the chemical industry and many other industries? Can you give some concepts about the chemical-product industry? Can you tell something about the chemical-process industry? Has the chemical industry been steadily expanding and how? Can you give some concepts of "petro-chemical industry"?

This illustrates the fact that a raw materials referred to here are those which become a part of the finished product itself or are used directly in manufacturing operations.

As has been indicated, this classification includes 1. In the chemical industry the segregation between semifinished and finished product is particularly difficult, since many chemical products are not only sold as such but are also consumed in the manufacture of other end products.

However, a material cannot be classified in two categories within a company, and one or the other must be selected. Usually, decision is influenced by the fact that more of the material is sold than consumed, or vice versa.

If more is consumed, and then the material becomes a semifinished product; if more is sold, the material is classified as finished product.

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Read and translate into Vietnamese inventory, materials, semifinished, products, raw materials, salable, prefabrication, illustrate, manufacture, perform, segregation, selected, category, influenced, consumed.

What are the inventories? Can you tell something about inventories? What are raw materials? Give an example. What are processed materials?

Can you tell the difference between semifinished and finished products? All scientists have the obligation to prepare written reports of the results of experimental work. Since this record may be studied by many individuals, it must be completed in a clear, concise and accurate manner. This means that procedural detail, observations and results must be recorded in a laboratory notebook while the experiment is being performed. The notebook should be hardbound with quadrille-ruled gridded pages and used only for the biochemistry laboratory.

This provides a durable, permanent record and the potential for construction of graphs, charts, etc. It is recommended that the first one or two pages of the notebook be used for a constantly updated table of contents. Although your instructor may have his or her own rules for preparation of the notebook, the most readable notebooks are those in which only the right - hand pages are used for record keeping.

The left - hand pages may be used for your own notes, reminders and calculations. If a new technique or instrumental method is introduced, give a brief description of the method. Include chemical or biochemical reactions when appropriate.

Experimental Begin this section with a list of all reagents and materials used in the experiment. The sources of all chemical and the concentrations of solutions should be listed. Instrumentation is listed with reference to company name and model number. A flowchart to describe the stepwise procedure for the experiment should be included after the list of equipment. Experimental a Table of materials and reagents b List of equipment c Flowchart d Record of procedure Data and Calculations a Record of all raw data b Method of calculation with statistical analysis c Enter data in tables, graphs or figures when appropriate For the early experiments, a flowchart is provided.

Flowcharts for later experiments should be designed by the student. The write-up to this point is to be completed as a Prelab assignment. The experimental procedure followed is then recorded in your notebook as you proceed through the experiment. The detail should be sufficient so that a fellow student can use your notebook as a guide. You should include observations, such as color changes or gas evolution, made during the experiment.

Data and Calculations All raw data from the experiment are to be recorded directly in your notebook, not on separate sheets of paper. Calculations involving the data must be included for at least one series of measurements. Proper statistical analysis must be included in this section. The Analysis of Results section following each experimental procedure in this book describes the preparation of graphs and tables. These must all be included in your notebook.

Results and Discussion This is the most important section of your write-up, because it answers the questions:. Any conclusion that you make must be supported by experimental results. It is often possible to compare your data with known values and results from the literature. If this is feasible, calculate percentage error and explain any differences. Note if any problems were encountered in the experiments. All library references books and journal articles that were used to write up the experiment should be listed at the end.

The standard format to follow for a book or journal listing is shown at the end of this chapter in the reference section. Everyone has his or her own writing style, some better than others. It is imperative that you continually try to improve your writing skills. When your instructor reviews your write-up, he or she should include helpful writing tips in the grading.

Read and translate into Vietnamese experience, obligation, observation, notebook, statement, goals, discussion, description, biochemistry, material, instrumentation, flowchart, stepwise, measurement, presentation, significance B. What is the laboratory notebook? How many steps are there in experimental write-up?

What is the first section of experimental write-up? Tell something about it? Say a few words about calculations of experimental works? Why should we need discussion of experimental results? The interaction of atoms and molecules is called chemistry. The metabolic activities of microorganisms involve complex chemical reactions. Nutrients are broken down by microbes to obtain energy and to make new cells.

Structure of Atoms 1. Atoms are the smallest units of chemical elements that enter into chemical reactions. Atoms consist of a nucleus, which contains protons and neutrons and electrons that move around the nucleus.

The atomic number is the number of protons in the nucleus: Chemical Elements 1. Atoms with the same atomic number and same chemical behavior are classified as the same chemical element.

Chemical elements are designated by letter abbreviations called chemical symbols. There are about 26 elements commonly found in living cells. Atoms that have the same atomic number are of the same element but different atomic weights are called isotopes.

In an atom, electrons are arranged around the nucleus in electron shells. Each shell can hold a characteristic maximum number of electrons. The chemical properties of an atom are largely due to the number of electrons in its outermost shell.

Molecules are made up of two or more atoms; molecules consisting of at least two different kinds of atoms are called compounds. Atoms form molecules in order to fill their outermost electron shells. Attractive forces that bind the atomic nuclei of two atoms together are called chemical bonds. The combining capacity of an atom - the number of chemical bonds the atom can form with other atoms - is its valence. Ionic Bonds 1. A positively or negatively charged atom or group of atoms is called an ion.

A chemical attraction between ions of opposite charge is called an ionic bond. To form an ionic bond, one ion is an electron donor; the other ion is an electron acceptor. Covalent Bonds 1. In a covalent bond, atoms share pairs of electrons. Covalent bonds are stronger than ionic bonds and are far more common in organisms.

Hydrogen Bonds 1. A hydrogen bond exists when a hydrogen atom covalently bonded to one oxygen or nitrogen atom is attracted to another oxygen or nitrogen atom. Hydrogen bonds form weak links between different molecules or between parts of the same large molecule.

Molecular Weight and Moles 1. The molecular weight is the sum of the atomic weights of all the atoms in a molecule. A mole of an atom, ion, or molecule is equal to its atomic or molecular weight expressed in grams. The number of moles of a substance equals its mass in grams divided by its molecular weight. Chemical Reactions Chemical reactions are the making or breaking of chemical bonds between atoms.

Energy of Chemical Reactions 1. A change of energy occurs during chemical reactions. Endergonic reactions require energy, exergonic reactions release energy. In a synthesis reaction, atoms, ions, or molecules are combined to form a large molecule. In a decomposition reaction, a large molecule is broken down into its component molecules, atoms, and ions.

In an exchange reaction, two molecules are decomposed, and their subunits are used to synthesize two new molecules. The products of reversible reactions can readily revert back to form the original reactants. How Chemical Reactions Occur 1. For a chemical reaction to take place, the reactants must collide with each other.

The minimum energy of collision that can produce a chemical reaction is called its activation energy. Specialized proteins called enzymes accelerate chemical reactions in living systems by lowering the activation energy. Read and translate into Vietnamese interaction, metabolic, microorganisms, complex, nutrients, microbes, cells, behavior, symbol, properties, valence, covalent, attractive, attraction, express, subunits, collide, collision, activation energy, protein, enzymes B. What is the atom?

Say some words about chemical elements. Say something about chemical bonds. How do the chemical reactions occur? How many kinds of chemical reactions do you know? What are they?

Sewage includes all the water from a household that is used for washing as well as toilet wastes. Rainwater flowing into street drains and some industrial wastes enter the sewage systems in some cities.

Sewage is mostly water and contains little particulate matter perhaps only about 0. Even so, in large cities, this solid portion of sewage can total more than tons of solid material per day. Until environmental awareness intensified, a surprising number of large cities in which had only rudimentary sewage treatment systems or no system at all. If prompted, confirm your purchase by entering your password and any requested payment information. Find your book.

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