Ôn tập hóa học bằng tiếng anh

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.

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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:

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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 + 1 ½ O2 -> CO2 + H2O + NH3+ 736kJ
This process liberates a lot of energy which can be used by the saprotrophic
microbes
Nitrification:

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Denitrification:

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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
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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.


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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 2
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)

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(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


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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 3
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 4

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.

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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 5
a. Present soil phases in term of chemical composition.
b. Please write the structure of a ring phyllosilicate.
a.
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Present soil phases in term of chemical composition.
Air
Gases have atoms or molecules that do not bond to one another in a range of
pressure, temperature and volume.


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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 6
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.
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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


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b.

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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.


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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

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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

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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

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Question 7
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.
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b.
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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 do 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)


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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


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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.


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Solutions as Mixtures
A combination of two or more substances that do 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 9
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
do 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
1. 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 2 micrometers in diameter.
2. Surface area: Because of their small size, all soil colloids expose a large
external surface per unit mass. The external surface area of 1 g of colloidal clay
is at least 1000 times that of 1 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
3. 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.

4. 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.
6. 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.
7. 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.
8. 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.
9. 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.
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Stability of colloid suspensions is a balance between repulsive and attractive
forces interacting among the suspended particles.


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If net repulsive force predominate, then particles do 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.

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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 do
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+ + 2 NaCl ⇄ [colloid]2Na+ + CaCl2
Chỗ này viết thêm cũng đc, k thì thôi cũng đc
Ca2+-colloid + 2 Na+  2 Na+-colloid + Ca2+
= Na+
replaces Ca+2 adsorbed to soil colloids
Ca-x + 2 Na+  2 Na-X + Ca2+
X = the soil solid phase
Question 14: Use of Langmuir Equation in estimating adsorption capacity
(Sử dụng các phương trình Langmuir trong việc 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