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1) Grammar - Past Forms - выполнить упражнения стр. с 1 по 13
https://drive.google.com/drive/folders/1dsOHTimSb-FmCTpAOG_v53T1zs7uT5SH
2) Reading/Translating/Tests -
а) https://www.ck12.org/book/ck-12-chemistry-intermediate/section/15.0/
b)https://www.ck12.org/book/ck-12-chemistry-intermediate/section/15.1/
3) Topics - из того, что Вы подготовили
4) Speaking FCE - письменно в блоге выполнить задание 1(проверить порядок и правила работы в Вашем блоге); стр. 152
https://drive.google.com/drive/folders/1ukwAtoadb3V8KInF9pDnK9kKhoakU9oC
Мы продолжаем наши занятия. Напоминаю Вам о том, что необходимо направить мне ваши дипломные работы в электронном ГОТОВОМ виде на почту для проверки, а также предоставить папку по переводческому практикуму на подпись.
1) Grammar - Past Forms - выполнить упражнения стр. с 1 по 13
https://drive.google.com/drive/folders/1dsOHTimSb-FmCTpAOG_v53T1zs7uT5SH
2) Reading/Translating/Tests -
а) https://www.ck12.org/book/ck-12-chemistry-intermediate/section/15.0/
b)https://www.ck12.org/book/ck-12-chemistry-intermediate/section/15.1/
3) Topics - из того, что Вы подготовили
4) Speaking FCE - письменно в блоге выполнить задание 1(проверить порядок и правила работы в Вашем блоге); стр. 152
https://drive.google.com/drive/folders/1ukwAtoadb3V8KInF9pDnK9kKhoakU9oC
FCE test 6
ОтветитьУдалитьUse of English 89%
Listening 90%
Алимханова
ОтветитьУдалить15.1
1. The molecule adopts a bent structure because of the two lone pairs of electrons on the oxygen atom. The H-O-H bond angle is about 105°.
2. Electronegativity determines whether it acquires a positive or negative partial charge when participating in a polar covalent bond. The oxygen atom acquires a partial negative charge (δ−), while the hydrogen atoms each acquire a partial positive charge (δ+).
3. Each oxygen atom has two lone pairs, it can make hydrogen bonds to the hydrogen atoms of two other molecules.
4. Between 4°C and 0°C, the density of water gradually decreases as the hydrogen bonds begin to form a network characterized by a generally hexagonal structure with open spaces in the middle of the hexagons.
5. If the ice were to sink as it froze, entire lakes would freeze solid. Since the ice does not sink, liquid water remains under the ice all winter long. This is important, as fish and other organisms are capable of surviving through winter.
6. Relatively few molecules of water are capable of escaping the surface of the liquid and entering the vapor phase. Because evaporation is slow, the resulting vapor exerts a low pressure in a closed container. Low vapor pressure is an important physical property of water that prevents lakes, oceans, and other large bodies of water from evaporating at a much faster rate.
7. a. 95,84 ml
b. 100 ml
c. 99,98 ml
d. 91,68 ml.
8. The volume of water increases (as the density of ice is lower) and the bottle bursts.
9. а.Тhe density of water is higher than the density of ice.
b. The hydrogen bonding between liquid water molecules explains water’s low vapor pressure.
c. Water has a high surface tension because of its strong intermolecular hydrogen bonds.
Алимханова
Удалить15.3
1. A suspension is a heterogeneous mixture in which some of the particles settle out of the mixture upon standing. The particles in a suspension are far larger than those of a solution, so gravity is able to pull them down out of the dispersion medium (water).
2. Particle size of colloids is 1-1000 nm.
3. The Tyndall effect is the scattering of visible light by colloidal particles. When light is passed through a true solution, the dissolved particles are too small to deflect the light.
4. The dispersed phase describes the particles, while the dispersion medium is the material in which the particles are distributed.
5. An emulsion is a colloidal dispersion of a liquid in either a liquid or a solid. A stable emulsion requires an emulsifying agent to be present.
6. Since the salt dissolves in water, a homogeneous solution will be obtained with stirring, so a spoon of salt in water is not a suspension.
7. a. suspension
b. suspension, colloid
c. solution
d. suspension, colloid
e. solution
f. colloid, suspension
g. colloid
h. colloid, solution
i. colloid
Grammar test.Past tenses :92%
ОтветитьУдалить15.3
ОтветитьУдалить1. A suspension is a heterogeneous mixture in which some of the particles settle out of the mixture upon standing. The particles in a suspension are far larger than those of a solution, so gravity is able to pull them down out of the dispersion medium (water).
2. 1-1000 nm.
3. The Tyndall effect is the scattering of visible light by colloidal particles. When light is passed through a true solution, the dissolved particles are too small to deflect the light.
4. The dispersed phase describes the particles, while the dispersion medium is the material in which the particles are distributed.
5. An emulsion is a colloidal dispersion of a liquid in either a liquid or a solid. A stable emulsion requires an emulsifying agent to be present.
6. As the salt dissolves in water, a homogeneous solution will be obtained with stirring, that means a spoon of salt in water is not a suspension.
7. a. suspension
b. suspension, colloid
c. solution
d. suspension, colloid
e. solution
f. colloid, suspension
g. colloid
h. colloid, solution
i. colloid
15.1
ОтветитьУдалить1. The molecule adopts a bent structure because of the two lone pairs of electrons on the oxygen atom. The H-O-H bond angle is about 105°.
2. Electronegativity determines whether it acquires a positive or negative partial charge when participating in a polar covalent bond. The oxygen atom acquires a partial negative charge (δ−), while the hydrogen atoms each acquire a partial positive charge (δ+).
3. Each oxygen atom has two lone pairs, it can make hydrogen bonds to the hydrogen atoms of two other molecules.
4. Between 4°C and 0°C, the density of water gradually decreases as the hydrogen bonds begin to form a network characterized by a generally hexagonal structure with open spaces in the middle of the hexagons.
5. Since the ice does not sink, liquid water remains under the ice all winter long. This is important, as fish and other organisms are capable of surviving through winter.
6. Relatively few molecules of water are capable of escaping the surface of the liquid and entering the vapor phase. Because evaporation is slow, the resulting vapor exerts a low pressure in a closed container. Low vapor pressure is an important physical property of water that prevents lakes, oceans, and other large bodies of water from evaporating at a much faster rate.
7. a. 95,84 ml
b. 100 ml
c. 99,98 ml
d. 92,68 ml.
8. The volume of water increases (as the density of ice is lower) and the bottle bursts very soon.
9. а.Тhe density of water is higher than the density of ice.
b. The hydrogen bonding between liquid water molecules explains water’s low vapor pressure.
c. Water has a high surface tension because of its strong intermolecular hydrogen bonds.
Алимханова
ОтветитьУдалитьGrammar past
94%
Test 15.2
ОтветитьУдалить1.solvent -water,solute - sugar
2.
Nonpolar compounds also do not dissolve in water. The attractive forces that operate between the particles in a nonpolar compound are weak dispersion forces. In order for a nonpolar molecule to dissolve in water, it would need to break up some of the hydrogen bonds between adjacent water molecules. In the case of an ionic substance, these favorable interactions are replaced by other attractive interactions between the ions and the partial charges on water. However, interactions between nonpolar molecules and water are less favorable than the interactions that water makes with itself. When a nonpolar liquid such as oil is mixed with water, two separate layers form, because the liquids will not dissolve into each other. When a polar liquid like ethanol is mixed with water, they completely blend and dissolve into one another. Liquids that dissolve in one another in all proportions are said to be miscible. Liquids that do not dissolve in one another are called immiscible. The general rule for deciding if one substance is capable of dissolving another is “like dissolves like,” where the property being compared is the overall polarity of the substance. For example, a nonpolar solid such as iodine will dissolve in nonpolar lighter fluid, but it will not dissolve in polar water.
3.After coming apart from the crystal, the individual ions are then surrounded by solvent particles in a process called solvation.
Hydration is the process of solute particles being surrounded by water molecules arranged in a specific manner. Hydration helps to stabilize aqueous solutions by preventing the positive and negative ions from coming back together and forming a precipitate.
4.electrolytes
5.Iron is attracted to oxygen and nitrate to hydrogen.
6.A strong electrolyte is a solution in which a large fraction of the dissolved solute exists as ions.A weak electrolyte is a solution in which only a small fraction of the dissolved solute exists as ions.For example, nitrous acid only partially ionizes into hydrogen ions and nitrite ions when dissolved in water. Aqueous nitrous acid is composed of only about 5% ions and 95% intact nitrous acid molecules.
7.The general rule for deciding if one substance is capable of dissolving another is “like dissolves like,” where the property being compared is the overall polarity of the substance. For example, a nonpolar solid such as iodine will dissolve in nonpolar lighter fluid, but it will not dissolve in polar water.
8.b,d,f
9.a.CoCl3=Co3+ + 3Cl-
b .NH4Br =NH4+ + Br-
c.Al(NO3)3= Al3+ + 3 NO3 -
d.Na2CO3= 2 Na+ + CO3-
e.ZnSO4= Zn2+ + SO4 2-
f.Li2S= 2Li+ + S2-
10.2H2O+2F2=4 HF+O2
11.CH3OH+H2O =CH3O- + 2H+ + OH-
Алимханова
ОтветитьУдалитьTest 15.2
1.solvent -water,solute - sugar
2.
Nonpolar compounds also do not dissolve in water. The attractive forces that operate between the particles in a nonpolar compound are weak dispersion forces. In order for a nonpolar molecule to dissolve in water, it would need to break up some of the hydrogen bonds between adjacent water molecules. In the case of an ionic substance, these favorable interactions are replaced by other attractive interactions between the ions and the partial charges on water. However, interactions between nonpolar molecules and water are less favorable than the interactions that water makes with itself. When a nonpolar liquid such as oil is mixed with water, two separate layers form, because the liquids will not dissolve into each other. When a polar liquid like ethanol is mixed with water, they completely blend and dissolve into one another. Liquids that dissolve in one another in all proportions are said to be miscible. Liquids that do not dissolve in one another are called immiscible. The general rule for deciding if one substance is capable of dissolving another is “like dissolves like,” where the property being compared is the overall polarity of the substance. For example, a nonpolar solid such as iodine will dissolve in nonpolar lighter fluid, but it will not dissolve in polar water.
3.After coming apart from the crystal, the individual ions are then surrounded by solvent particles in a process called solvation.
Hydration is the process of solute particles being surrounded by water molecules arranged in a specific manner. Hydration helps to stabilize aqueous solutions by preventing the positive and negative ions from coming back together and forming a precipitate.
4.electrolytes
5.Iron is attracted to oxygen and nitrate to hydrogen.
6.A strong electrolyte is a solution in which a large fraction of the dissolved solute exists as ions.A weak electrolyte is a solution in which only a small fraction of the dissolved solute exists as ions.For example, nitrous acid only partially ionizes into hydrogen ions and nitrite ions when dissolved in water. Aqueous nitrous acid is composed of only about 5% ions and 95% intact nitrous acid molecules.
7.The general rule for deciding if one substance is capable of dissolving another is “like dissolves like,” where the property being compared is the overall polarity of the substance. For example, a nonpolar solid such as iodine will dissolve in nonpolar lighter fluid, but it will not dissolve in polar water.
8.b,d,f
9.a.CoCl3=Co3+ + 3Cl-
b .NH4Br =NH4+ + Br-
c.Al(NO3)3= Al3+ + 3 NO3 -
d.Na2CO3= 2 Na+ + CO3-
e.ZnSO4= Zn2+ + SO4 2-
f.Li2S= 2Li+ + S2-
10.2H2O+2F2=4 HF+O2
11.CH3OH+H2O =CH3O- + 2H+ + OH-
15.1
ОтветитьУдалить1. The molecule adopts a bent structure because of the two lone pairs of electrons on the oxygen atom. The H-O-H bond angle is about 105°.
2. Electronegativity determines whether it acquires a positive or negative partial charge when participating in a polar covalent bond. For example, the oxygen atom acquires a partial negative charge (δ−), while the hydrogen atoms each acquire a partial positive charge (δ+).
3. Each oxygen atom has two lone pairs, it can make hydrogen bonds to the hydrogen atoms of two other molecules.
4. Between 4°C and 0°C, the density of water gradually decreases as the hydrogen bonds begin to form a network characterized by a generally hexagonal structure with open spaces in the middle of the hexagons.
5. Ice is less dense than liquid water, so it floats. Ponds or lakes begin to freeze at the surface, closer to the cold air. A layer of ice forms, but it does not sink as it would if water did not freeze in this unique structure, which is dictated by its shape, polarity, and hydrogen bonding. If the ice were to sink as it froze, entire lakes would freeze solid. Since the ice does not sink, liquid water remains under the ice all winter long. This is important, as fish and other organisms are capable of surviving through winter.
6. The hydrogen bonding between liquid water molecules also explains water’s unusually low vapor pressure for a molecule of its size. Relatively few molecules of water are capable of escaping the surface of the liquid and entering the vapor phase. Because evaporation is slow, the resulting vapor exerts a low pressure in a closed container. Low vapor pressure is an important physical property of water that prevents lakes, oceans, and other large bodies of water from evaporating at a much faster rate.
7. a) 95,84 ml
b) 100 ml
c) 99,98 ml
d) 91,68 ml
8. The density of ice is lower so the volume of water increases and the bottle bursts.
9. a) The volume of water increases when the water freezes.
b) The hydrogen bonding between liquid water molecules explains water’s unusually low vapor pressure for a molecule of its size.
c) Water has a high surface tension because of its strong intermolecular hydrogen bonds. Surface tension can be seen by the curved meniscus or the spherical shape of falling drops.
Grammar - Past Forms - 85 %
Удалить15.1
ОтветитьУдалить1. The molecule adopts a bent structure because of the two lone pairs of electrons on the oxygen atom. The H-O-H bond angle is about 105°, slightly smaller than the ideal 109.5° of an sp3 hybridized atomic orbital.
2. Electronegativity determines whether it acquires a positive or negative partial charge when participating in a polar covalent bond. The oxygen atom acquires a partial negative charge (δ−), while the hydrogen atoms each acquire a partial positive charge (δ+).
3. Each oxygen atom has two lone pairs, it can make hydrogen bonds to the hydrogen atoms of two other molecules.
4. Between 4°C and 0°C, the density of water gradually decreases as the hydrogen bonds begin to form a network characterized by a generally hexagonal structure with open spaces in the middle of the hexagons.
5. Ice is less dense than liquid water, so it floats. Ponds or lakes begin to freeze at the surface, closer to the cold air. A layer of ice forms, but it does not sink as it would if water did not freeze in this unique structure, which is dictated by its shape, polarity, and hydrogen bonding. If the ice were to sink as it froze, entire lakes would freeze solid. Since the ice does not sink, liquid water remains under the ice all winter long. This is important, as fish and other organisms are capable of surviving through winter.
6. Relatively few molecules of water are capable of escaping the surface of the liquid and entering the vapor phase. Because evaporation is slow, the resulting vapor exerts a low pressure in a closed container. Low vapor pressure is an important physical property of water that prevents lakes, oceans, and other large bodies of water from evaporating at a much faster rate.
7. a. 95,84 ml b. 100 ml c. 99,98 ml d. 91,68 ml.
8. The volume of water increases (as the density of ice is lower) and the bottle bursts.
9. а.Тhe density of water is higher than the density of ice.
b. The hydrogen bonding between liquid water molecules explains water’s low vapor pressure.
c. Water has a high surface tension because of its strong intermolecular hydrogen bonds.
перевод 15.1
ОтветитьУдалитьсвойство воды
По сравнению с другими молекулярными соединениями с относительно низкой молярной массой лед тает при очень высокой температуре. Чтобы разорвать водородную сеть льда и вернуть ее в жидкое состояние, требуется очень много энергии. Точно так же и температура кипения воды очень высока. Большинство молекулярных соединений с одинаковой молярной массой являются газами при комнатной температуре. поверхностное натяжение
Поверхностное натяжение обсуждалось в главе "состояния вещества". Вода имеет высокое поверхностное натяжение из-за своих сильных межмолекулярных водородных связей. Поверхностное натяжение можно увидеть по изогнутому мениску, который образуется, когда вода находится в тонком столбе, таком как градуированный цилиндр или бюретка. давление пара
Водородная связь между молекулами жидкой воды также объясняет необычно низкое давление водяного пара для молекулы такого размера. Относительно немногие молекулы воды способны покинуть поверхность жидкости и войти в паровую фазу. Поскольку испарение происходит медленно, образующийся пар оказывает низкое давление в закрытом контейнере. Низкое давление пара является важным физическим свойством воды, которое предотвращает испарение озер, океанов и других крупных водоемов с гораздо более высокой скоростью.
Test 15.2
ОтветитьУдалить1.solvent -water,solute - sugar
2.
Nonpolar compounds also do not dissolve in water. The attractive forces that operate between the particles in a nonpolar compound are weak dispersion forces. In order for a nonpolar molecule to dissolve in water, it would need to break up some of the hydrogen bonds between adjacent water molecules. In the case of an ionic substance, these favorable interactions are replaced by other attractive interactions between the ions and the partial charges on water. However, interactions between nonpolar molecules and water are less favorable than the interactions that water makes with itself. When a nonpolar liquid such as oil is mixed with water, two separate layers form, because the liquids will not dissolve into each other. When a polar liquid like ethanol is mixed with water, they completely blend and dissolve into one another. Liquids that dissolve in one another in all proportions are said to be miscible. Liquids that do not dissolve in one another are called immiscible. The general rule for deciding if one substance is capable of dissolving another is “like dissolves like,” where the property being compared is the overall polarity of the substance. For example, a nonpolar solid such as iodine will dissolve in nonpolar lighter fluid, but it will not dissolve in polar water.
If the difference in values of electronegativity is very large, then the compounds are polar else non polar.
Consider a compound KCl, K is in IA (3rd Period) and Cl in VIIA (3rd Period). difference in en values is very large, therefore Cl will attract the electron cloud toward itself. hence it is polar. All ionic compounds are polar in nature.
However polarity can also be achieved in covalent compound if the difference in en value is large. consider HCl, difference in en value is large, Cl is more electronegative than H, therefore, Cl will attract electron cloud toward itself and will develop a slight -ve charge and H will develop slight +ve charge. Therefore HCl is a polar compound.
If you consider an heterogenous compound such as NH3. diff . in en value is less therefore it is non-polar.
3.
Hydration is the process of solute particles being surrounded by water molecules arranged in a specific manner. Hydration helps to stabilize aqueous solutions by preventing the positive and negative ions from coming back together and forming a precipitate.
4.electrolytes
5.Iron is attracted to oxygen and nitrate to hydrogen.
6.A strong electrolyte is a solution in which a large fraction of the dissolved solute exists as ions.A weak electrolyte is a solution in which only a small fraction of the dissolved solute exists as ions.For example, nitrous acid only partially ionizes into hydrogen ions and nitrite ions when dissolved in water. Aqueous nitrous acid is composed of only about 5% ions and 95% intact nitrous acid molecules.
7.The general rule for deciding if one substance is capable of dissolving another is “like dissolves like,” where the property being compared is the overall polarity of the substance. For example, a nonpolar solid such as iodine will dissolve in nonpolar lighter fluid, but it will not dissolve in polar water.
8.b,d,f
9.a.CoCl3=Co3+ + 3Cl-
b .NH4Br =NH4+ + Br-
c.Al(NO3)3= Al3+ + 3 NO3 -
d.Na2CO3= 2 Na+ + CO3-
e.ZnSO4= Zn2+ + SO4 2-
f.Li2S= 2Li+ + S2-
10.2H2O+2F2=4 HF+O2
Ex.1
ОтветитьУдалитьDrops,writes,sneezes,drives
Goes,kisses,mixes,reaches,smashes
Buys,saya,pays
Cries,dries,tries
Ex.2
Bringing,going,crying
Tying,dying
Diving,hoping,coming
Running, travelling, putting
Ex.3
2)met
3)swum
4)finished
5)brought
6)sent
7)written
8)read
Ex.4
2)-g, 3)-h, 4)f, 5)b,6)a, 7)d,8)c,9)j, 10)i
Ex.5
2)have
3)are looking
4)love
5) take
6)Do you want
7)are having
8)is
Ex.6
2)am
3)don’t usually call
4) are coming
5)am booking
6)leaves
7)arrives
Ex.7
2)never wears
3)always does
4)often goes
5)sometimes walks the dog
Ex.8
2)Does your family often eat out? Yes we do.No,we don’t
3)Do you usually have dinner at 8:00 p.m?Yes,I do. No,I don’t
4)Do you often hang out with your friends? Yes,I do.No,I don’t
5)Does your dad usually wash the dishes?Yes,he does. No,he doesn’t
Ex.9
2)taste
3)Are you enjoying
4)are you thinking
5)has
6)smell
7)don’t know
8)fell
9)are you smelling
10)comes
11)looks
12)aren’t looking
13)is weighing
14)is being
Ex.10
1)think
2)are you weighting
Weight
3)is
Is being
4)have
Am having
5)are you testing
testes
6)comes
Is coming
7)see
Is seeing
Ex.11
2)has he been in
3)has gone to
4)Has anyone gone to
5)has been to
Ex.12
2)He has gone to the dentist’s
3)I have been there twice
4)I have been playing rugby for two Hours
5)she has been working hard since 9:30 this morning
6)they have gone to the cinema with friends
Ex.13
2)yet
3)since
4)How long
5)often
6)for
Ex.14
2)haven’t been exercising
3)have put on
4)have decided
5)have joined
6)have been
7)have made
8)have been studying
9)Have you thought
Ex.16
2)b
3)c
4)a
5) c
6)d
7)b
Ex.17
2)are staying
3)are having
4)are
5)are building
6)have been playing
7)has just gone
8)go
9)have tried
10)Haven’t done
11)are going
Structure of Water
УдалитьAs discussed in earlier chapters, water is a simple molecule consisting of one oxygen atom bonded to two different hydrogen atoms. Because of the higher electronegativity of the oxygen atom, the bonds are polar covalent. The oxygen atom attracts the shared electrons of the covalent bonds to a significantly greater extent than the hydrogen atoms. As a result, the oxygen atom acquires a partial negative charge (δ−), while the hydrogen atoms each acquire a partial positive charge (δ+). The molecule adopts a bent structure because of the two lone pairs of electrons on the oxygen atom. The H-O-H bond angle is about 105°, slightly smaller than the ideal 109.5° of an sp3 hybridized atomic orbital. The bent shape of the water molecule is critical because the polar O-H bonds do not cancel one another, so the molecule as a whole is polar. The figure below (Figure below) illustrates the net polarity of the water molecule. The oxygen is the negative end of the molecule, while the area between the hydrogen atoms is the positive end of the molecule.
Структура воды
Как уже говорилось в предыдущих главах, вода-это простая молекула, состоящая из одного атома кислорода, связанного с двумя различными атомами водорода. Из-за более высокой электроотрицательности атома кислорода эти связи являются полярно-ковалентными. Атом кислорода притягивает общие электроны ковалентных связей в значительно большей степени, чем атомы водорода. В результате атом кислорода приобретает частичный отрицательный заряд (δ -), а атомы водорода-частичный положительный заряд (δ+). Молекула принимает изогнутую структуру из-за двух одиночных пар электронов на атоме кислорода. Значение валентного угла нон составляет около 105°, немного меньше, чем идеальные 109,5 ° гибридной атомной орбитали sp3.
Изогнутая форма молекулы воды имеет решающее значение, потому что полярные связи О-Н не взаимно компенсируют друг друга, поэтому молекула в целом является полярной. Рисунок ниже (рисунок ниже) иллюстрирует чистую полярность молекулы воды. Кислород-это отрицательный конец молекулы, а область между атомами водорода-положительный конец молекулы.
Этот комментарий был удален автором.
УдалитьTest 15.1
Удалить1. The molecule adopts a bent structure because of the two lone pairs of electrons on the oxygen atom. The H-O-H bond angle is about 105°, slightly smaller than the ideal 109.5° of an sp3 hybridized atomic orbital.
2. The ability of an atom to attract electrons in a chemical bond is called the electronegativity of the atom. The electronegativity of an atom is related to its electron affinity and ionization energy
3. Each water molecule can form two hydrogen bonds involving their hydrogen atoms plus two further hydrogen bonds utilizing the hydrogen atoms attached to neighboring water molecules
4. When water freezes, water molecules form a crystalline structure maintained by hydrogen bonding. Solid water, or ice, is less dense than liquid water. Ice is less dense than water because the orientation of hydrogen bonds causes molecules to push farther apart, which lowers the density.
5. If ice were more dense than water, it would freeze and sink over and over until the entire lake was frozen. This would eliminate many aquatic organisms and produce a system with far fewer life forms in lakes which freeze periodically.
6. Relatively few molecules of water are capable of escaping the surface of the liquid and entering the vapor phase. Because evaporation is slow, the resulting vapor exerts a low pressure in a closed container. Low vapor pressure is an important physical property of water that prevents lakes, oceans, and other large bodies of water from evaporating at a much faster rate.
7. a. 95,84 ml
b. 100 ml
c. 99,98 ml
d. 91,68 ml.
8. The water will turn to ice.The volume of ice is greater than the volume of water.The bottle will burst
9. a. Increase in volume when water turns to ice
b. The hydrogen bonding between liquid water molecules explains water’s low vapor pressure.
c.Great tension relations of the water
Перевод отрывка
ОтветитьУдалитьStructure of Water
As discussed in earlier chapters, water is a simple molecule consisting of one oxygen atom bonded to two different hydrogen atoms. Because of the higher electronegativity of the oxygen atom, the bonds are polar covalent. The oxygen atom attracts the shared electrons of the covalent bonds to a significantly greater extent than the hydrogen atoms. As a result, the oxygen atom acquires a partial negative charge (δ−), while the hydrogen atoms each acquire a partial positive charge (δ+). The molecule adopts a bent structure because of the two lone pairs of electrons on the oxygen atom. The H-O-H bond angle is about 105°, slightly smaller than the ideal 109.5° of an sp3 hybridized atomic orbital. The bent shape of the water molecule is critical because the polar O-H bonds do not cancel one another, so the molecule as a whole is polar. The figure below (Figure below) illustrates the net polarity of the water molecule. The oxygen is the negative end of the molecule, while the area between the hydrogen atoms is the positive end of the molecule. Polar molecules attract one another by dipole-dipole forces; the positive end of one molecule is attracted to the negative end of a nearby molecule. In the case of water, the highly polar O-H bonds leave very little electron density around the hydrogen atoms. Each hydrogen atom is strongly attracted to the lone-pair electrons on the oxygen atom of an adjacent molecule. These are called hydrogen bonds, and they are stronger than conventional dipole-dipole forces. Because each oxygen atom has two lone pairs, it can make hydrogen bonds to the hydrogen atoms of two other molecules. The figure below (Figure below) shows the result—an approximately tetrahedral geometry around each oxygen atom consisting of two covalent bonds and two hydrogen bonds.
структура воды
УдалитьКак уже говорилось в предыдущих главах, вода-это простая молекула, состоящая из одного атома кислорода, связанного с двумя различными атомами водорода. Из-за более высокой электроотрицательности атома кислорода эти связи являются полярно-ковалентными. Атом кислорода притягивает общие электроны ковалентных связей в значительно большей степени, чем атомы водорода. В результате атом кислорода приобретает частичный отрицательный заряд (δ−), а атомы водорода-частичный положительный заряд (δ+). Молекула принимает изогнутую структуру из-за двух одиночных пар электронов на атоме кислорода. Угол связи H-O-H составляет около 105°, что немного меньше идеального 109,5° гибридизованной атомной орбитали sp3. Изогнутая форма молекулы воды имеет решающее значение, потому что полярные связи O-H не отменяют друг друга, поэтому молекула в целом полярна. Рисунок ниже иллюстрирует чистую полярность молекулы воды. Кислород-это отрицательный конец молекулы, а область между атомами водорода-положительный конец молекулы. Полярные молекулы притягиваются друг к другу диполь-дипольными силами; положительный конец одной молекулы притягивается к отрицательному концу соседней молекулы. В случае воды высокополярные связи O-H оставляют очень малую электронную плотность вокруг атомов водорода. Каждый атом водорода сильно притягивается к одиночным парам электронов на атоме кислорода соседней молекулы. Они называются водородными связями, и они сильнее обычных диполь-дипольных сил. Поскольку каждый атом кислорода имеет две одиночные пары, он может создавать водородные связи с атомами водорода двух других молекул. На рисунке ниже показан результат—приблизительно тетраэдрическая геометрия вокруг каждого атома кислорода, состоящая из двух ковалентных связей и двух водородных связей.
Test 15.1
ОтветитьУдалить1. The molecule adopts a bent structure because of the two lone pairs of electrons on the oxygen atom. The H-O-H bond angle is about 105°.
2. Electronegativity determines whether it acquires a positive or negative partial charge when participating in a polar covalent bond. The oxygen atom acquires a partial negative charge (δ−), while the hydrogen atoms each acquire a partial positive charge (δ+).
3. Each oxygen atom has two lone pairs, it can make hydrogen bonds to the hydrogen atoms of two other molecules.
4. Between 4°C and 0°C, the density of water gradually decreases as the hydrogen bonds begin to form a network characterized by a generally hexagonal structure with open spaces in the middle of the hexagons.
5. Since the ice does not sink, liquid water remains under the ice all winter long. This is important, as fish and other organisms are capable of surviving through winter.
6. Relatively few molecules of water are capable of escaping the surface of the liquid and entering the vapor phase. Because evaporation is slow, the resulting vapor exerts a low pressure in a closed container. Low vapor pressure is an important physical property of water that prevents lakes, oceans, and other large bodies of water from evaporating at a much faster rate.
7. a. 95,84 ml
b. 100 ml
c. 99,98 ml
d. 92,68 ml.
8. The volume of water increases (as the density of ice is lower) and the bottle bursts very soon.
9. а.Тhe density of water is higher than the density of ice.
b. The hydrogen bonding between liquid water molecules explains water’s low vapor pressure.
c. Water has a high surface tension because of its strong intermolecular hydrogen bonds.