Ôn tập hóa học bằng tiếng anh

18 2.1K 2
Ôn tập hóa học bằng tiếng anh

Đang tải... (xem toàn văn)

Tài liệu hạn chế xem trước, để xem đầy đủ mời bạn chọn Tải xuống

Thông tin tài liệu

Question 1: a. Present a nitrogen cycle within the earth system. b. Present organic matter classification in soils. c. Write a cellulose molecular structure with four sugar monosaccharides. a. Present a nitrogen cycle within the earth system. From the diagram of global nitrogen cycle, we can summarize key processes:  Stock of soil nitrogen depends on N fixation processes and decay processes of organic N compounds.  Major fixation processes consist of biological fixation and HaberBosh process.  Decay processes include ammonification (mineralization), nitrification, denitrification.  Biological N fixation:  HaberBoschindustrial N fixation: The Haber Process combines nitrogen from the air with hydrogen derived mainly from natural gas (methane) into ammonia. N2 + 3H2 > 2NH3 (ΔH = −92.4 kJ•mol−1)  Ammonificationmineralization: Nitrogen enters the soil through the decomposition of protein in dead organic matter Amino acids + 1 ½ O2 > CO2 + H2O + NH3+ 736kJ This process liberates a lot of energy which can be used by the saprotrophic microbes  Nitrification:  Denitrification: Denitrification is a natural soil microbial process where nitrate (NO3 ) is converted to nitrogen (N) gases that are lost to the atmosphere. b. Present organic matter classification in soils. There are many classifications of soil organic mater.  NONHUMIC SUBSTANCES • Carbohydrates  Carbohydrates consists of monosaccharides (single sugars), disaccharides, polysaccharides. The simplest carbohydrates are monosaccharides, or single sugars.  Carbohydrate macromolecules are polysaccharides, polymers composing of many sugar building blocks. • Proteins  Proteins account for more than 50% of the dry mass of most cells.

Question 1: a Present a nitrogen cycle within the earth system b Present organic matter classification in soils c Write a cellulose molecular structure with four sugar monosaccharides + a Present a nitrogen cycle within the earth system From the diagram of global nitrogen cycle, we can summarize key processes:  Stock of soil nitrogen depends on N fixation processes and decay processes of organic N compounds  Major fixation processes consist of biological fixation and Haber-Bosh process  Decay processes include ammonification (mineralization), nitrification, denitrification Biological N fixation: + Haber-Bosch/industrial N fixation: The Haber Process combines nitrogen from the air with hydrogen derived mainly from natural gas (methane) into ammonia N2 + 3H2 -> 2NH3 (ΔH = −92.4 kJ·mol−1) Ammonification/mineralization: Nitrogen enters the soil through the decomposition of protein in dead organic matter Amino acids + ½ O2 -> CO2 + H2O + NH3+ 736kJ This process liberates a lot of energy which can be used by the saprotrophic microbes Nitrification: + Denitrification: + + Denitrification is a natural soil microbial process where nitrate (NO3- ) is converted to nitrogen (N) gases that are lost to the atmosphere b Present organic matter classification in soils There are many classifications of soil organic mater Organic Carbon in soil Biomass Carbon in living organic Humus Soil organic matter Nonhumic substances Humic acid ∗ • + + • + + Organic Carbon in undecayed and partially decayed plant and animals tissues Humic substances Fulvic acid Humin NONHUMIC SUBSTANCES Carbohydrates Carbohydrates consists of monosaccharides (single sugars), disaccharides, polysaccharides The simplest carbohydrates are monosaccharides, or single sugars Carbohydrate macromolecules are polysaccharides, polymers composing of many sugar building blocks Proteins Proteins account for more than 50% of the dry mass of most cells Protein functions include structural support, storage, transport, cellular communications, movement, defense against foreign substances + • + + • + + + • + + + + ∗ Enzymes are a type of protein that acts as a catalyst, speeding up chemical reactions Enzymes can perform their functions repeatedly, functioning as workhorses that carry out the processes of life Lipids Fats are constructed from two types of smaller molecules: glycerol and fatty acids Glycerol is a three-carbon alcohol with a hydroxyl group attached to each carbon A fatty acid consists of a carboxyl group attached to a long carbon skeleton Fatty acids vary in length (number of carbons) and in the number and locations of double bonds Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds Unsaturated fatty acids have one or more double bonds The major function of fats is energy storage Lignins Lignin may be defined as an amorphous, polyphenolic material arising from enzymatic dehydrogenative polymerization of three phenylpropanoid monomers, namely, coniferyl alcohol, sinapyl alcohol, and p-coumaryl alcohol It is most commonly derived from wood, and it is an integral part of the secondary cell walls of plants and some algae In short, lignins compose of coniferyl alcohol (softwood), signapyl alcohol (hardwood), p-coumaryl alcohol (grasswood) Lignin is a cross-linked racemic macromolecule with molecular masses in excess of 10,000 u ADN Nucleic acids are polymers called polynucleotides Each polynucleotide is made of monomers called nucleotides Each nucleotide consists of a nitrogenous base, a pentose sugar and a phosphate group The portion of a nucleotide without the phosphate group is called a nucleoside HUMIC SUBSTANCES Humic substances (HS) are complex and heterogeneous mixtures of polydispersed materials formed in soils, sediments, and natural waters by biochemical and chemical reactions during the decay and transformation of plant and microbial remains (a process called humification) Plant lignin and its transformation products, polysaccharides, melanin, cutin, proteins, lipids, nucleic acids, fine char particles, etc., are important components taking part in this process c Write a cellulose molecular structure with four sugar monosaccharides Question a Present soil colloid classification b Present concepts of adsorption, absorption, desorption, adsorbate, adsorbent a Present soil colloid classification Soil colloids can be classified by crystal structure (a) (b) • • • • • (c) (d) Crystalline Silicate Clays • Dominant colloid in most soils (not andisols, oxisols or organic soils) • Crystals layered as in a book • 2-4 sheets of tightly-bonded O, Si and Al atoms in each layer  Kaolinite  Smectite group  Vermiculite group  Mica group  Chlorites Non-crystal colloids  Salts:CaCO3 – calcite, aragonite CaMgCO3 – dolomite CaSO4 – gypsum Ca5(PO4)3F, Ca5(PO4)3OH – flour – hidroxiapatite Ca3(PO4)2 – photphorite Not organized into crystalline sheets Both + and – charges can adsorbanions such as photphorite High water – holdingcapacity Malleable (charges in shape) when wet but not sticky Often form in volcanic soils (especially in Andisoils) Fe, Al oxides Fe3O4 – magnetite Fe2O3 – hematite Al(OH)3 – gibbsite Humic colloids Anon – crystalline, organic substance Very large, organic molecules ≈ 50% C, 40% O, 5% H, 3% N and sometimes S Structure highly variable Very large negative charge due to three types of – OH groups    carboxyl group COOH phenolic hydroxyl group alcoholic hydroxyl group b Present concepts of adsorption, absorption, desorption, adsorbate, adsorbent Adsorption is a physical process that involves the transfer of solutes from the liquid phase to the surface of a solid matrix Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface Absorption is the filling of pores in a solid When both adsorption and absorption processes take place simultaneously, the process is called sorption Desorption: The process of removal of an adsorbed substance from the surface on which it is absorbed Adsorbent, adsorbate: The substance on the surface of which adsorption takes place is called adsorbent The substance which is being adsorbed on the surface of another substance, called adsorbate Question a Present Jackson-Sherman weathering stages b State soil organic matter classification (ý b câu 1) a Jackson-Sherman Weathering The relationship between weathering intensity and the mineral assemblages present in the clay fraction of a soil is described in the weathering sequence of Jackson et al (1948) and Jackson and Sherman (1953) Jackson reasoned that the mineral composition of the clay-sized fraction could be employed to establish the weathering stage of a soil Common minerals found in the clay fraction of a soil are identified by an index number Low numbers represent minerals easily weathered Whereas high numbers represent minerals relatively resistant to weathering and abundant in old soils The clay fraction of a soil is typically composed of three to five dominant minerals Question a Present the concepts of permanent structural charge, proton charge, innersphere complex charge, ouster-sphere complex charge b Present a structure of soil colloids c Please explain differences between physical adsorption and chemical adsorption a Present the concepts of permanent structural charge, proton charge, innersphere complex charge, ouster-sphere complex charge a Permanent structural change Isomorphous substitution of layer colloids creates negative charge of particle surface This charge is termed permanent structural charge, σo In addition, reaction between surface functional groups with solution ions generates proton charge σH, inner complex charge σis, oyster complex charge σOS b Inner sphere complex charge adsorbed ions and molecules (other than H+ and OH-) σis Inner sphere complex charge density σis can be positive, negative or zero Ouster-sphere complex charge Ions and molecules that are held at the surface σOS, the Ouster-sphere complex charge σOS can be positive, negative or zero b Present a structure of soil colloids Negatively charged colloidal particles: Nuclear Negative charge surface Fixed cation layer Exchangeable cation layer Positively charged colloidal particles: Nuclear Positive charge surface Fixed anion layer Changeable anion layer Negatively charged clay particles: Nuclear Negative charge surface (charge layer of colloidal particles) c − − − − ∗ − − − − ∗ − − d Please explain differences between physical adsorption and chemical adsorption Physical adsorption: Van der Waals attraction between adsorbate and adsorbent The attraction is not fixed to a specific site and the adsorbate is relatively free to move on the surface This is relatively weak, reversible, adsorption capable of multilayer adsorption Chemical adsorption: Some degree of chemical bonding between adsorbate and adsorbent characterized by strong attractiveness Adsorbed molecules are not free to move on the surface There is a high degree of specificity and typically a monolayer is formed The process is seldom reversible Cause Temperature range Heat adsorption physical adsorption chemical adsorption Van der Waals forces, no Covalent/electrostatic forces, electron transfor electron transfer Low temperatures Generally high temperatures of Low, ≈ heat of fusion High, ≈ heat of reaction (80 – 200 (ca.10kJ/mol), always (600)kJ/mol), usually exothermic exothermic Rate Vert fast Strongly temperature dependent Activation energy Low Generally high (unactivated: low) Surface coverage Mutilayers Monolayer Question a Present soil phases in term of chemical composition b Please write the structure of a ring phyllosilicate a •  Present soil phases in term of chemical composition Air Gases have atoms or molecules that not bond to one another in a range of pressure, temperature and volume  •    •    b These molecules haven’t any particular order and move freely within a container Liquids Similar to gases, liquids haven’t any atomic/molecular order and they assume the shape of the containers Applying low levels of thermal energy can easily break the existing weak bonds Liquid crystals have mobile molecules, but a type of long range order can exist; the molecules have a permanent dipole Applying an electric field rotates the dipole and establishes order within the collection of molecules Solids Solids consist of atoms or molecules executing thermal motion about an equilibrium position fixed at a point in space Solids can take the form of crystalline,polycrstalline, or amorphous materials Solids (at a given temperature, pressure, and volume) have stronger bonds between molecules and atoms than liquids Solids require more energy to break the bonds Please write the structure of a ring phyllosilicate Phyllosilicates, or sheet silicates, are an important group of minerals that includes micas, chlorite, serpentine, talc, clay minerals The basic structure of the phyllosilicates is based on interconnected six member rings of SiO4 -4 tetrahedra that extend outward in infinite sheets Each tetrahedra is bound to three neighboring tetrahedra via three basal bridging oxygens Question a Explain the origin of permanent structural charge of soil clay colloids b Present adsorption types of soils c Indicate the significances of soil adsorption in soil management a − Explain the origin of permanent structural charge of soil clay colloids Isomorphous subsitution of layer colloids creates negative charge of particle surface This charge is termed permanent oσstructural charge • • − b c − Each Mg2+ ion that substitutes for Al3+ causes a negative charge in a dioctahedral sheet Each Al3+ ion that substitutes for Si4+ causes a negative charge in a tetrahedral sheet In addition, reaction between surface funtional groups with solution ions generates proton charge σH , inner complex charge σis , ouster complex charge σcharge Present adsorption types of soils Physical adsorption: Van der Waals attraction between adsorbate and adsorbent The attraction is not fixed to a specific site and the adsorbate is relatively free to move on the surface This is relatively weak, reversible, adsorption capable of multilayer adsorption Chemical adsorption: Some degree of chemical bonding between adsorbate and adsorbent characterized by strong attractiveness Adsorbed molecules are not free to move on the surface There is a high degree of specificity and typically a monolayer is formed The process is seldom reversible Indicate the significances of soil adsorption in soil management Adsorption is a physical process that involves the transfer of solutes from the liquid phase to the surface of a solid matrix − ∗ • Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface the significances of soil adsorption in soil management is ability to retain water, nutrients and conditioner nutrition soil Chemical adsorption has meaning for properties and soil fertility This is the cause of accumulation of nutrients in the soil such as Al, P, Fe, S, in which the element beneficial to crops such as P,Ca,S, or reduce the tisicity of some other element like Al • Because soil colloids have large specific surface and one layer of ions surrounded It can hold the opposite ions around That is the basic of calculation of soil adsorption • The relationship between adsorption capacity and the ions outside solution is the exchange relationship If concentrations of solution is high, soil colloids will adsorp ions in solution If the solution to low concentrations of ions from soil colloids are released out In addition to the absorption capacity of soil also through the attraction od food crops and microorganisms, capable of keeping the maater particle through small slit, rugged shores or retained for soil molecules precipitate, or air molecules, other water • Question a Present soil element classifications b State concepts of soil colloids, nanoparticles, clay particles, soil particles c Please explain roles of surface functional groups of clay colloids a − − − − − − b • • Soil element classifications: Metals Transition metals Nonmetals Noble gases Lanthanide series Actinide series State concepts of soil colloids, nanoparticles, clay particles, soil particles Soil colloids is a particle with a size of less than 1µm Any substance finely dispersed in a gaseous, liquid, or solid medium, such that individual particles They are not visible in an ordinary microscope They not settle out Nanoparticles is critical size range (or particle diameter) typically ranges from nanometers (10−9 m) to micrometers (10−6 m) The term colloid is used primarily to describe a broad range of solid–liquid (and/or liquid–liquid) • • c    • • •     • mixtures, all of which containing distinct solid (and/or liquid) particles that are dispersed to various degrees in a liquid medium Clay particles: The contact of rocks and water produces clays, either at or near the surface of the earth Soil particles is major component of soil.They have vary size, shapes depending on the impact of the weathering process and the process of moving, deposition Surface functional groups of clay colloids Types of surface functional groups Surface functional groups (SFG) play a significant role in soil adsorption processes SFG is a chemically reactive molecular unit bound into the structure of a solid at its periphery It acts as the reactive components of the units can be bathed by a fluid (Sposito, 1989) SFG can be organic (carboxyl, carbonyl, phenolic…) or inorganic units Clay colloids carry negative or positive charges on their external and internal surfaces The presence of charge influences their ability to attract or repulse charge ions to or from surfaces Surfaces of clay minerals usually have negative charges due to either isomorphous substitution, or weak organic acids(COOH groups) These charges attract or hold positively charged ions (CATIONS) in equilibrium with other cations in solution • Surface functional groups of clay colloids Siloxane surface group  It associates with silica tetrahedral sheet of a phyllosilicate  Siloxane acts as a Lewis base Surface functional groups of organic colloids Organic matter in surface functional groups between colloidal particles and liquid Many functional groups depending on conditions of pH functional groups affect the adsorption capacity of cation or anion The most common functional groups is carboxyl (COOH), phenolic OH, carbonyl (CO) carboxyl and sulfonic complexes with protons very weak This group s negatively charge and save cation amine, imide, phenolic OH, sulfhydryl is absorbed proton selective group, They accumulate and absorb the positive charge anion Surface complexes  Interaction of surface functional groups with an ion or molecule present in the soil solution create an stable molecular entity, called a surface complex  Two types of surface complexes are inner-sphere and outer-sphere complexes If water molecule is present between surface functional group − − − − − − − a b a and ion or molecule, it is termed outer-sphere complex If there is no a water molecule present between ion or molecule and surface functional group to which it is bound, this is an innersphere complex  The formation of the complexes occurs at the edge of clay minerals  Outer-sphere complexes involves electrostatic coulombic interactions and are weak compared to innersphere complexes in which the binding is covalent or ionic Outer-sphere complexation is usually a rapid process that is reversible  Inner-sphere complexation is normally slower than outer-sphere complexation It is not often reversible This process can increase, reduce or neutralize or reverse charge on the sorptive regardless of the original charge This process may occur on a surface regardless of the surface charge Siloxane surface group: It associates with silica tetrahedral sheet of a phyllosilicate Siloxane acts as a Lewis base Hydroxyl group (OH): It associates with the edge of clay colloids such as kaolinite This surface groups can be protonated or deprotonated by absorption of H+ and OH- Lewis acids are denoted by S, deprotonated surface hydroxyls are Lewis bases Lewis acid sites are present not only the metal oxides such as on the edge of gibbsite or goethite, but also on the edge of clay minerals Example: hydroxyl (OH) surface functional group of clay, gibbsite S – OH At the edge of octahedral sheet, OH groups are coordinated to Al+3 At the tetrahedral sheet, OH groups are coordinated to Si+4 OH groups coordinated to Si+4 dissociate only protons But, OH groups coordinated to Al+3 dissociate and bind protons These edge OH groups called silanol (SiOH), aluminol (AlOH) Clay minerals have both aluminol, silanol OH group Question 8: State concepts of solution, solute, solvent, mixtures Present the types of soluble complexes in soils State concepts of solution, solute, solvent, mixtures Solutions define as a homogeneous mixture of two or more substances in a aqueous phase Usually a solid is dissolved in a liquid, but liquids can be dissolved in other liquids Gases can be dissolved in a liquid as well Component (substance) present in greater proportion is called the solvent, the one in minor proportion is called the solute Examples of solution, oceans are salt water solutions— water is the solvent, salt is the solute Sweet tea in another example — sugar is the solute and water is the solvent b − − Solutions as Mixtures A combination of two or more substances that not combine chemically, but remain the same individual substances They can be separated by physical means such as temperature Two types of mixtures: Heterogeneous mixtures and Homogeneous mixtures Present the types of soluble complexes in soils Classification of soluble complexes There are various ways to classify soluble complexes A common way is based on charge of the complexes A positively charged complex ion is called a cation complex A cation complex is a positively charged ion A negatively charged complex ion is called an anion complex An anion complex is a negatively charged Based on bridging types between central ion and ligand, soluble complexes can be classified into inner-sphere complexes and outer-sphere complexes Based on interactions between charged species (ions) with water molecules, soluble complexes can be referred as solvation complexes and non salvation complexes Question a Present nitrogen cycle within the earth system (ý a câu 1) b Explain the terms of nanoparticles, clay particles, soil particles c Present soil organic matter classification (ý b câu 1) Question 10 a Present major characteristics of soil colloids b Compare differences between chemical adsorption and physical adsorption (ý c câu 4) a Present major characteristics of soil colloids Soil colloids is a particle with a size of less than 1µm Any substance finely dispersed in a gaseous, liquid, or solid medium, such that individual particles They are not visible in an ordinary microscope They not settle out This shows that the size of colloid particles is less than the size of bacteria and Agaes Surface charge Tension surface Colloid coagulation and dispersion Size: The most important common property of inorganic and organic colloids is their extremely small size They are too small to be seen with an ordinary light microscope Only with an electron microscope they can be seen Most are smaller than micrometers in diameter Surface area: Because of their small size, all soil colloids expose a large external surface per unit mass The external surface area of g of colloidal clay is at least 1000 times that of g of coarse sand Some colloids, especially certain silicate clays have extensive internal surfaces as well These internal surfaces occur between plate like crystal units that make up each particle and often greatly exceed the external surface area The total surface area of soil colloids ranges from 10 m2/g for clays with only external surfaces to more than 800 m2/g for clays with extensive internal surfaces The colloid surface area in the upper 15 cm of a hectare of a clay soil could be as high 700,000 km2/g Surface charges: Soil colloidal surfaces, both external and internal characteristically carry negative and/or positive charges For most soil colloids, electro negative charges predominate Soil colloids both organic and inorganic when suspended in water, carry a negative electric charge When an electric current is passed through a suspension of soil colloidal particles they migrate to anode, the positive electrode indicating that they carry a negative charge The magnitude of the charge is known as zeta potential The presence and intensity of the particle charge influence the attraction and repulsion of the particles towards each other, there by influencing both physical and chemical properties The negative electrical charge on clays comes from i) Ionizable hydrogen ions and ii) Isomorphism substitution Adsorption of cations: As soil colloids possess negative charge they attract the ions of an opposite charge to the colloidal surfaces They attract hundreds of positively charged ions or cation such as H+, A13+ Ca2+ , and Mg2+ This gives rise to an ionic double layer The process, called Isomorphous substitution and the colloidal particle constitutes the inner ionic layer, being essentially huge anions; with both, external and internal layers that are negative in charge The outer layer is made up of a swarm of rather loosely held (adsorbed) cations attracted to the negatively charged surfaces Thus a colloidal particle is accompanied by a swarm of cations that are adsorbed or held on the particle surfaces 5 Adsorption of water: In addition to the adsorbed cations, a large number of water molecules are associated with soil colloidal particles Some are attracted to the adsorbed cations, each of which is hydrated; others are held in the internal surfaces of the colloidal particles These water molecules play a critical role in determining both the physical and chemical properties of soil Cohesion: Cohesion is the phenomenon of sticking together of colloidal particles that are of similar nature Cohesion indicates the tendency of clay particles to stick together This tendency is primarily due to the attraction of the clay particles for the water molecules held between them When colloidal substances are wetted, water first adheres to the particles and then brings about cohesion between two or more adjacent colloidal particles Adhesion: Adhesion refers to the phenomenon of colloidal particles sticking to other substances It is the sticking of colloida1 materials to the surface of any other body or substance with which it comes in contact Swelling and shrinkage: Some clay (soil colloids) such as smectites swell when wet and shrink when dry After a prolonged dry spell, soils high in smectites (e.g Vertisols) often are crises-crossed by wide, deep cracks, which at first allow rain to penetrate rapidly Later, because of swelling, such soil is likely to close up and become much more impervious than one dominated by kaolinite, chlorite, or fine grained micas Vermiculite is intermediate in its swelling and shrinking characteristics Dispersion and flocculation:  Dispersion: the reverse of coagulation is dispersion Ideally the amount of energy required to separate two particles coagulated into a potential energy minimum is approximately equal to the difference between the interaction energy at the minimum - Under constant chemical conditions, separation of particles can be induced from an input of kinetic energy such as thermal or mechanical shear - Alternatively, changing chemical conditions of bulk solution surrounding coagulated particles could provide chemical or electrochemical energy to produce dispersion  Flocculation (coagulation) is process of contact and adhesion of particles of dispersion larger size clusters • Stability of colloid suspensions is a balance between repulsive and attractive forces interacting among the suspended particles • • If net repulsive force predominate, then particles not coagulate and remain dispersed When attractive force is dominant, interacting particles coagulate and settle more rapidly from suspension the smaller dispersed particles Question 11 a State soil element classifications (ý a câu 7) b Present Jackson-Sherman weathering stages (ý a câu 3) Question 12 a Present the terms of solute, solvent, homogeneous mixtures, heterogeneous mixtures b Explain interaction between water molecules and ions in forming hydrated complex ions c Write an example of cation exchange reaction of Ca-Na in soils − − − − − − − b a Present the terms of solute, solvent, homogeneous mixtures, heterogeneous mixtures Solutions define as a homogeneous mixture of two or more substances in a aqueous phase Usually a solid is dissolved in a liquid, but liquids can be dissolved in other liquids Gases can be dissolved in a liquid as well Component (substance) present in greater proportion is called the solvent, the one in minor proportion is called the solute Examples of solution, oceans are salt water solutions— water is the solvent, salt is the solute Sweet tea in another example — sugar is the solute and water is the solvent Solutions as Mixtures: A combination of two or more substances that not combine chemically, but remain the same individual substances They can be separated by physical means such as temperature Two types of mixtures: Heterogeneous mixtures Homogeneous mixtures Heterogeneous Mixtures “Hetero” means different It consists of visibly different substances or phases (solid, liquid, gas) A suspension is a special type of heterogeneous mixture of larger particles that eventually settle Soil solution may be defined as heterogeneous mixture Homogeneous Mixtures “Homo” means the same Has the same uniform appearance and composition throughout; maintain one phase (solid, liquid, gas) Commonly referred to as solutions Water molecules in close proximity to the charged ion will become ordered and form a shell around the ion Water molecules in close proximity to the charged ion will become ordered and form a shell around the ion If the ion is a cation, partially negative portion of the water molecule (oxygen portion) will be attracted to and pointing toward cation The protons will be repelled and pointing outward Conversely, water molecules in close proximity to an anion will be oriented with the protons pointing toward the anion Water molecules that reside in the region closest to an ion occupy the primary hydration sphere of the ion, also termed the coordination sphere of the ion In this sphere there is strong attraction between the water molecules and the ion Water molecules that are outside the primary sphere, but influenced by the ion, reside in the secondary hydration sphere Hydrated complex ion (solvate) contains a metal ion and its ligands H20 c Exchange reaction: [colloid]Ca2+ + NaCl ⇄ [colloid]2Na+ + CaCl2 Chỗ viết thêm đc, k đc Ca2+-colloid + Na+  Na+-colloid + Ca2+ = Na+ replaces Ca+2 adsorbed to soil colloids Ca-x + Na+  Na-X + Ca2+ X = the soil solid phase Question 14: Use of Langmuir Equation in estimating adsorption capacity (Sử dụng phương trình Langmuir việc ước tính khả hấp phụ) Phương trình Langmuir dạng đường cong L: q= Trong đó: q lượng hấp phụ (µg/kg) b lượng hấp phụ cực đại (µg/kg) (µg/l) nồng độ chất bị hấp phụ dd trạng thái cân KL đại lượng mức độ hấp phụ (in units of L per kg of absorbent) Hoặc: q= =b Question 13: Calculate CEC using colloid formula and negative charge method [...]... ước tính khả năng hấp phụ) Phương trình Langmuir dạng đường cong L: q= Trong đó: q là lượng hấp phụ (µg/kg) b là lượng hấp phụ cực đại (µg/kg) (µg/l) là nồng độ chất bị hấp phụ trong dd ở trạng thái cân bằng KL là đại lượng chỉ mức độ hấp phụ (in units of L per kg of absorbent) Hoặc: q= =b Question 13: Calculate CEC using colloid formula and negative charge method

Ngày đăng: 21/07/2016, 22:38

Từ khóa liên quan

Mục lục

  • Because soil colloids have large specific surface and one layer of ions surrounded. It can hold the opposite ions around. That is the basic of calculation of soil adsorption

Tài liệu cùng người dùng

  • Đang cập nhật ...

Tài liệu liên quan