《基礎(chǔ)化學》英文教學課件：chapter-5

1、Chapter 5. Colloids 5-1. colloids 5-2. Sol 5-3. Macromolecular solution 5-4. Surfactants and associated colloids1 膠體分散系明確分散系；分散相；分散介質(zhì)；均相體系；非均相體系；相的概念；明確比表面；表面能的概念；明確 分散相的分類方法；2 溶膠明確 溶膠；電泳；電滲；臨界聚沉濃度的概念；理解溶膠的性質(zhì)：光學性質(zhì)；動力學性質(zhì)；電學性質(zhì)明確溶膠的結(jié)構(gòu)：膠核；膠粒；吸附層；擴散層；雙電層概念理解膠粒的電屬性；理解溶膠的穩(wěn)定性及聚沉；Learning Objectives3 高分子溶液明確

2、 高分子溶液；等電點的概念；理解 高分子溶液的屬性；理解 鹽析，電泳分離和純化蛋白的機制；4 表面活性劑和締合膠體明確 表面能；表面張力；增溶的概念；明確 膠束；臨界膠束濃度；締合膠體的概念；理解 表面活性劑的分類；1. ColloidsA solution is a homogeneous (均相的) mixture of two or more substances, consisting of ions or molecules.A colloid (膠體) is a dispersion of particles (1 100 nm) of one substance througho

3、ut another substance or solution.Concept introduction:NaCl aqueous solution: Na+, Cl-, H2OFog is an example of a colloid: it consists of very small water droplets in air.Proteins, nucleic acids, blood, body fluid, cell.T.Thomas Graham (18051869) Peter P. von Weymarn (1879 1935) 擴散速度小，不能透過半透膜，溶劑蒸發(fā)后不結(jié)

4、晶，而是形成無定形膠狀物的物質(zhì)。T.Thomas Graham (18051869) 任何能結(jié)晶的物質(zhì)在一定介質(zhì)中用適當?shù)姆椒ǘ寄艹蔀槟z體膠體是物質(zhì)的一種分散狀態(tài)的概念1. Colloids1. ColloidsI. Dispersed systemDispersed phase (分散相):to be dispersed, discontinuousDispersed medium (分散介質(zhì)):to disperse, continuousA dispersed system (分散系) is formed by dispersing one or more substances thro

5、ughout another substance.1. ColloidsClassification of dispersed systems: AA heterogeneous system (非均相體系) is a mixture that consists of physically distinct parts, each with different properties. A homogeneous system (均相體系, also known as a solution) is a mixture that is uniform in its properties throu

6、ghout given samples.K2CrO4 + Fe fillings1. ColloidsA phase (相) is one of several different homogeneous materials present in the portion of matter under study.These heterogeneous systems all consist of two different phases.K2CrO4 + Fe fillingsicewatericeNaClsolution1. ColloidsClassification of disper

7、sed systems: BClassification according to the size of dispersed phase.Sol 固-液 Sol 液-氣Sol 固-氣Coloured stained glass Sol 固-固乳狀液Milky Way?凝膠The Milky Way is the galaxy that contains our Solar System. An image of the Milky Ways Galactic Center in the night sky above Paranal Observatory可憐織女星，化為馬郎婦。烏鵲疑不來，

8、迢迢牛奶路。-出自魯迅的教授雜詠四首 The Milky Way is the galaxy that contains our Solar System. 魯迅(1881年9月25日-1936年10月20日） 吶喊狂人日記阿Q正傳1. ColloidsII. Colloid dispersed systemA colloid is a dispersion of particles (1 100 nm) of one substance (the dispersed phase) throughout another substance or solution (the dispersed

9、medium or the continuous phase (連續(xù)相).Sol (溶膠)Macromolecular solution (高分子溶液)Associated colloid (締合膠體)1. Colloids1. SolA sol (溶膠) is a colloid consisting of solid particles (collection of atoms, molecules, or ions) dispersed in a liquid. heterogeneous and unstable1. ColloidsDegree of dispersion (分散度)

10、:A cube with a size of 1 cm:Specific surface area (比表面, S0): surface area occupied by the substance of a unit volume.1 cm1. ColloidsDisperse the cube to cubes with a size of 1 m, the number of smaller cubes is:Then, Disperse the cube to cubes with a size of 1 nm, the number of smaller cubes is:Then,

11、 1 cm1 m1 nm1. ColloidsA molecule at the surface experiences a net force toward the interior of the liquid, whereas a molecule in the interior experiences no net force.There is a tendency for the surface area of a liquid to be reduced as much as possible. This explains why falling raindrops are near

12、ly spherical (the sphere has the smallest surface area for a given volume of any geometrical shape).1. ColloidsSurface energy (表面能): The energy required to increase the surface area by a unit amount. (Jm-2).OR. The molecules at the surface have higher energy than those in the interior.Sol is highly

13、dispersed and has a higher surface energy. It has a tendency to aggregate to decrease the surface energy. Therefore, sol is an unstable system.energy1. ColloidsThe dispersed phase is single (large) molecules, macromolecular solutions are stable systems.2. Macromolecular solution (高分子溶液)1. ColloidsTh

14、e dispersed phase is molecular cluster. Associated colloids are stable systems.3. Associated colloid (締合膠體)Sodium stearate(硬脂酸鈉)2. SolMulti-phase;Highly-dispersed;Unstable.2. SolI. Properties of sol1. Optical properties (光學性質(zhì)) : Tyndall effectThe scattering (散射) of light by colloidal-size particles

15、is known as the Tyndall effect.A light beam is visible perpendicular to its path only if light is scattered toward the viewer. Colloidsolution2. SolScattering of (strong) laser beams by air molecules2. Sol2. SolRayleigh formula:I0: Incident light intensity: Incident light wavelength V: particle volu

16、me c: concentration of particles n: refractive index (折光指數(shù))Colloidsolution2. SolAlthough all gases and liquids scatter light, the scattering from a pure substance or true solution is quite small and usually not detectable. However, because of the considerable depth of the atmosphere, the scattering

17、of light by air molecules can be seen. The blue color of the sky is due to the fact that blue light is scattered more easily than red light.Rayleigh formula:I0: Incident light intensity: Incident light wavelength V: particle volume c: concentration of particles n: refractive index兩眼一眨不眨勇敢的盯著太陽直到太陽和我

18、都變瞎天黑了地黑了太陽也黑了好久好久才醒過來感覺到天地由黑轉(zhuǎn)白黎明從我這里向四面八方展開牛漢-童癖六首（1923年10月2013年9月29日） Rayleigh scattering is more evident after sunset. This picture was taken about one hour after sunset at 500m altitude, looking at the horizon where the sun had set.早霞不出門，晚霞行千里2. Sol2. Dynamic properties (動力學性質(zhì)) Brownian movement

19、 (布朗運動):The phenomenon that colloidal particles move irregularly and continuously in the medium. 2. SolIt is resulted from the unbalanced collision from medium molecules. Decreasing sol particle size and viscosity (粘度) of medium, or increasing the temperature, favors Brownian movement.Sol: dynamical

20、ly stable system.2. Sol Diffusion and sedimentation equilibrium:Diffusion (擴散): The phenomenon that colloidal particles shift from a region with higher concentration to that with lower concentration. Reason: Brownian movement; Driving forces: concentration difference.2. SolSedimentation (沉降): The ph

21、enomenon that colloidal particles tend to sink due to gravitation.Sedimentation equilibrium: when diffusion and sedimentation are at equilibrium, a concentration gradient (梯度) occurs.It takes a very long time to reach this equilibrium, to accelerate this process Ultracentrifugation (超速離心法)2. Sol在密度均

22、一的介質(zhì)中由低速到高速逐級離心，用于分離不同大小的細胞和細胞。 differentialcentrifugation 差速離心 densitygradientcentrifugation 密度梯度離心用一定的介質(zhì)在離心管內(nèi)形成一連續(xù)或不連續(xù)的密度梯度，將細胞混懸液或勻漿置于介質(zhì)的頂部，通過重力或離心力場的作用使細胞分層、分離。 A等速度沉降，分離密度相近而大小不等的細胞或細胞器。 B等密度沉降 , 適用于分離密度不等的顆粒。 2. Sol+-3. Electric properties Electrophoresis:2. SolElectrophoresis (電泳): directiona

23、l movement of charged colloidal particles in an electric field.+-NaCl solutionFe(OH)3 solPositively-charged Fe(OH)3 colloidal particlesApplications: separation and identification of amino acids, polypeptides, proteins, and nucleic acids.2. SolInstrument for electrophoresis.Separation and identificat

24、ion proteins by electrophoresis.2. Sol2. SolElectroosmosis (電滲): directional movement of dispersed medium in an electric field.Reason: charging state of colloidal particles and medium.-colloidal particles fixed in a membrane+capillary(毛細管)2. SolII. Structure of solAgNO3 + KI AgI + KNO3 KI in excess;

25、AgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+Colloidal particle(膠粒)Colloidal nucleus(膠核)Sol1. Structure of sol2. SolAgImnI-(n-x)K+x-xK+Colloidal nucleusAdsorption layerDiffusion layerColloidal particleSolAgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+Colloidal particle(膠粒膠粒)Colloidal nucle

26、us(膠核膠核)SolAgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+Colloidal particle(膠粒膠粒)Colloidal nucleus(膠核膠核)Sol2. SolAdsorption layer (吸附層): the thin layer composed of adsorbed ions on the colloidal nucleus surface and part of the confined counterions (反離子).Diffusion layer (擴散層): the layer composed

27、 of the rest of counterions diffusing around the adsorption layer.Electric double layer (雙電層): the two-layer structure of oppositely-charged adsorption layer and diffusion layer.Absorption (吸收)2. SolAgImnAg+(n-x)NO3-x+xNO3-Colloidal nucleusAdsorption layerDiffusion layerColloidal particleSolAgNO3 +

28、KI AgI + KNO3 AgNO3 in excess;AgINO3-Ag+Colloidal particleColloidal nucleusSolAg+Ag+Ag+Ag+Ag+Ag+Ag+NO3-NO3-NO3-NO3-NO3-NO3-NO3-2. SolFe(OH)3mnFeO+(n-x)Cl-x+xCl-Colloidal nucleusAdsorption layerDiffusion layerColloidal particleSolFeCl3 + 3H2O Fe(OH)3 + 3HClFe(OH)3 + HCl FeOCl + 2H2OFeOCl FeO+ + Cl-Fe

29、(OH)3Cl-FeO+Colloidal particleColloidal nucleusSolFeO+FeO+FeO+FeO+FeO+FeO+FeO+Cl-Cl-Cl-Cl-Cl-Cl-Cl-2. Sol2. Electrically-charged colloidal particles1). Selective adsorption to the colloidal nucleus surface: Fe(OH)3 colloidal particles appear to be positively-charged due to selective adsorption of Fe

30、O+.Fe(OH)3Cl-FeO+Colloidal particleColloidal nucleusSolFeO+FeO+FeO+FeO+FeO+FeO+FeO+Cl-Cl-Cl-Cl-Cl-Cl-Cl-2. SolAgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+AgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+AgNO3 + KI AgI + KNO3AgINO3-Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+NO3-NO3-NO3-NO3-NO3-NO3-NO3-AgNO3 in

31、 excessKI in excess2. SolSilica sol colloidal particles appear to be negatively-charged.H2SiO3 HSiO3- + H+HSiO3- SiO32- + H+2). Dissociation of surface molecules around colloidal nucleus:Silica sol:Nucleus: xSiO2yH2OSurface: H2SiO32. SolAgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+AgIK+I-I-I-I

32、-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+3). Effect of electrolyteelectrolyteelectrolyteelectrolyteAgI+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+AgII-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+K+AgII-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+AgII-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+K+2. S

33、olIII. Stability of solElectrically-charged colloidal particles: Electrostatic repulsion among colloidal particles.Protection of hydrated membrane (水合膜) around colloidal particle: Elastic membrane.Brownian movement.A colloid of gold particles (negatively-charged) in water prepared by Michael Faraday

34、 in 1857 is still preserved in the British Museum in London.Solutions of gold nanoparticles of various sizes. The size difference causes the difference in colors.2. Sol免疫金標記技術(shù)(Immunogold labelling techique) 在金標蛋白結(jié)合處，在顯微鏡下可見黑褐色顆粒，當這些標記物在相應(yīng)的配體處大量聚集時，肉眼可見紅色或粉紅色斑點，因而用于定性或半定量的快速免疫檢測方法中，這一反應(yīng)也可以通過銀顆粒的沉積被放大

35、，稱之為免疫金銀染色。納米金即指金的微小顆粒，其直徑在1100nm，具有高電子密度、介電特性和催化作用，能與多種生物大分子結(jié)合，且不影響其生物活性。2. Solaccumulations of gold particles over the neural granules 2. Sol2. SolIV. Coagulation of solCoagulation (聚沉) is the process by which the dispersed phase (colloidal particles of sol) is made to aggregate and thereby separa

36、te from the dispersed medium (continuous phase).An example is the coagulation of a colloidal suspension of soil in river water when the water meets the concentrated ionic solution of an ocean. The river delta (三角洲) was formed in this way. Nile River delta, as seen from Earth orbit. The Nile is an ex

37、ample of a wave-dominated delta that has the classic Greek delta (,) shape after which river deltas were named.2. SolDeltas on Mars Finding deltas is a major sign that Mars once had a lot of water. 2. Sol2. SolElectrolyte can push counterions to the adsorption layer and neutralize (中和) the charging

38、state of colloidal particles. Two colloidal particles can approach close enough to aggregate. Critical coagulation concentration (CCC, 臨界聚沉濃度): the minimum concentration of electrolyte needed to coagulate a certain amount of sol within a specified time.1. Effect of electrolyte electrolyteAgII-I-I-I-

39、I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+AgII-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+K+AgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+AgIK+I-I-I-I-I-I-I-I-I-I-I-I-K+K+K+K+K+K+K+K+K+K+K+2. SolCritical coagulation concentration (mmolL-1)2. SolA. The greater the magnitude of the charge of the cou

40、nterion, the lower the CCC is.Shulze-Hardy rule:B. Same magnitude of the charge of the counterion , coagulation capacity: For negatively-charged sol: H+ Cs+ Rb+ NH4+ K+ Na+ Li+ For positively-charged sol:F- Cl- Br- I- CNS-2. Sol2. Coagulation of mixed sols with opposite electric charges Fe(OH)3Cl-Fe

41、O+FeO+FeO+FeO+FeO+FeO+FeO+FeO+Cl-Cl-Cl-Cl-Cl-Cl-Cl-+3. Macromolecular SolutionMacromolecule (polymer): a chemical species of very high molecular weight (10,000) made up from many units of low molecular weight linked together. Macromolecular solution is a kind of molecular solution. It is a homogeneo

42、us and stable system. However, the size of macromolecules falls into the range of colloidal dispersed system.Polymers are natural or synthetic (next slide).I. MacromoleculesMacromolecular solution solHeterogeneous systemHomogeneous systemStable systemsUnstable systemsuncharged colloidal particlesCha

43、rged colloidal particlesViscosity, osmotic pressure Low viscosity and osmotic pressure solvation, Salting out Coagulation 3. Macromolecular SolutionFlexible-chain:good solvent3. Macromolecular Solution3. Macromolecular SolutionBranched polymer(枝化高分子) Hyperbranched polymer(高枝化高分子)Dendrimer(樹形高分子)Line

44、ar polymer(線形高分子)Uniform structural unit:Polyethylene (聚乙烯): (C2H4)nNatural rubber: (C5H8)nPolysaccharide (多糖): (C6H10O5)nNon-uniform structural unit:Protein (蛋白質(zhì)): amino acidsNucleic acid (核酸): nucleotides (核苷)A polymer(聚合物) is a chemical species of very high molecular mass made up from many struct

45、ural unit or monomer of low molecular mass covalently linked together. A compound used to make a polymer (and from which the polymers unit arises) is called a monomer(單體).3. Macromolecular Solution“團結(jié)就是力量”3. Macromolecular Solution“鎖鏈化學”Celluloid, discovered around 1868, was the first commercial pla

46、stic. Initially it was used as a cheap substitute for ivory in making billiard balls. Cellulose (纖維)Cellulose nitrate (guncotton) is made by soaking a cellulose material such as cotton in a mixture of nitric and sulfuric acids.it catches fire and burns explosively. Table tennis ballscelluloid film3.

47、 Macromolecular SolutionBakelite, a hard plastic produced from formaldehyde, HCHO, and phenol, C6H5OH.Leo Baekeland利奧 貝克蘭(1863 1944) Bakelite buttons Bakelite酚醛樹脂(1907)3. Macromolecular SolutionNatural rubber is a homopolymer(同聚物), a polymer whose monomer units are all alike.A copolymer(共聚物) is a po

48、lymer consisting of two or more different monomer units. Styrenebutadiene rubber (SBR) is an important synthetic rubber;3. Macromolecular SolutionPolyesters (聚酯)A substance with two alcohol groups reacts with a substance with two carboxylic acid groups to form a polyester, a polymer whose repeating

49、units are joined by ester groups.Dacron(滌綸)The product, although interesting, tended to decompose in hot water and had a low melting point, so as a fabric it would hardly withstand washing or ironing.3. Macromolecular SolutionPolyamides (聚酰胺)When a compound containing two amine groups reacts with a

50、compound containing two carboxylic acid groups, a condensation polymer called a polyamide is formed.Nylon-6,6 (尼龍，1935)A condensation polymer(縮合聚合物) is a polymer formed by linking together many molecules by condensation reactions. A condensation reaction is one in which two molecules are joined by t

51、he elimination of a small molecule such as water.3. Macromolecular SolutionWallace Carothers華萊士卡羅瑟斯(1896年1937年) 3. Macromolecular SolutionPlexiglass (acrylic) 有機玻璃(丙烯酸樹脂)Teflon特氟龍(聚四氟乙烯)3. Macromolecular Solution“不粘鍋”涂層3. Macromolecular SolutionPETEPolyethylene terephthalate聚對苯二甲酸乙二醇酯 PP Polypropyle

52、ne聚丙烯 3. Macromolecular SolutionHDPE High-density polyethylene高密度聚乙烯 LDPE Low-density polyethylene低密度聚乙烯塑料3. Macromolecular SolutionPS Polystyrene聚苯乙烯PVC Polyvinyl chloride聚氯乙烯 3. Macromolecular SolutionPC Polycarbonates聚碳酸酯Bisphenol A 雙酚3. Macromolecular Solution3. Macromolecular SolutionII. Protei

53、n solution1. ProteinProtein (蛋白質(zhì)) are biological polymers of amino acids linked by peptide bonds.+peptide bond (肽鍵)Amino acid (氨基酸) R:3. Macromolecular Solution2. Isoelectric pointLower pHHigher pHSide chains become protonated and carry positive charges.Side chains become deprotonated and carry nega

54、tive charges.Protonation (質(zhì)子化) means the gain of a proton; Deprotonation (去質(zhì)子化) means the loss of a proton.3. Macromolecular SolutionThe pH at which a protein carries no net charge (same amount of negative charges and positive charges) is called the isoelectric point (等電點, pI) of this protein.pH pI

55、:negatively-charged.The isoelectric point of bovine serum albumin (牛血清白蛋白, BSA) is 4.6.Isoelectric point and electrophoresis, solubility.More specifically, the pI of any amino acid is the average of the two acid-dissociation constants that involve the neutral zwitterion. For the 13 amino acids with

56、a neutral side chain, pI is the average of pKa1 and pKa2 . For the four amino acids with either a strongly or weakly acidic side chain, pI is the average of the two lowest pKa values. For the three amino acids with a basic side chain, pI is the average of the two highest pKa values.3. Macromolecular

57、 Solution3. Macromolecular Solution3. Salting outThe primary structure (一級結(jié)構(gòu)) of a protein refers to the sequence of the amino-acid units in the protein.The secondary structure (二級結(jié)構(gòu)) refers to the relatively simple coiled or parallel arrangement of a protein molecule.The tertiary structure (三級結(jié)構(gòu)) r

58、efers to the structure associated with the way the protein coil is folded.Three-dimensional structure of myoglobin (肌球素)3. Macromolecular SolutionDue to the ion-dipole forces (離子-偶極作用力), the charges (ions) along protein molecules attract water molecules and are thus hydrated. Hydration (水合作用) of ion

59、s favors the dissolving of protein molecules in water.Hydration of ions. Note that a cation (a) is surrounded by water molecules with the O atoms closer to the ion, whereas an anion (b) has water molecules attached through their hydrogen atoms.3. Macromolecular SolutionWhen inorganic salt (for examp

60、le, (NH4)2SO4) are added into protein solution, the hydration of protein molecules is highly weakened due to the strong hydration of inorganic ions. The solubility of protein is lowered and protein molecules precipitate out of the solution. This process is referred to as salting out (鹽析).The structu