Colloidal Solutions

Total Page:16

File Type:pdf, Size:1020Kb

Colloidal Solutions COLLOIDAL SOLUTIONS Department of Medical Chemistry Pomeranian Medical University 1 COMPONENTS OF THE SYSTEM -chemicals which create the system. They create different type of mixtures - which makes the system to exists in various phases. PHASE – part of the system is separated from other phases with distinct border where sudden change in physico-chemical changes takes place. • Phase containing one component – pure substance • Phase containing more than one component - solution SOLUTION – mixture of two or more components dissolved in solvent (solvent-subtance in quantitative excess over other componet) 2 SYSTEMS Systems can be divided due to: 1) number of components: ➢ one-component ➢ multicomponent 2) number of phases : ➢ single phase ➢ multiple phase SYSTEMS: HETEROGENOUS –multiplephase (seemingly single-phase), heterogeneous; eg. water with ice (heterogeneous, two-phase, single- component system ), water with mercury (heterogeneous, two-phase, two- component system ) HOMOGENOUS –single-phase, homogeneous throughout the volume, both chemically and physically; e.g. glucose solution (homogeneous single phase, two components system) 3 Types of solutions depending on size of dispersed phase in dispersive medium TYPE OF SOLUTION DIAMETER OF PARTICLES OF DISPERSED PHASE True solution < 10-9 m (<1nm) (homogeneous) Colloidal (heterogeneous) 10-9 - 10-7 m (1-100 nm) Suspension > 10-7 m (>100 nm) 4 COLLOIDAL SOLUTIONS COLLOIDAL SOLUTIONS – heterogenous dispersive system with distinguished continuous scattering phase (solvent) and discontinuous dispersed phase with particle diameter of 10-9 - 10-7 m (1 – 100 nm, up to 500nm) All living cells are sets of various colloidal systems. Colloidal systems are widespread : in animate nature (proteins, carbohydrates) in inanimate nature (clay, fog, volcanic dust) synthetic materials (soap, colorants, colloidal sulphur, metal oxides) 5 COLLOIDAL SOLUTIONS COLLOIDAL SOLUTION – HETEROGENEOUS system - with particle size of 10-9-10-7m in diameter (1 – 100 nm, up to 500 nm) 10-9 m = 1 nm = 0.001 micron 10-7 m = 100 nm = 0.1 micron -6 10 m = 1000 nm = 1 micron 6 Properties of colloids (1): 1. They can be seen in ultra–microscope. Attention: the difference between an ultra-microscope and ordinary one is that in the former the light falls laterally on the liquid under study, instead of “from below”. The ordinary microscope with x400 magnifications has limitations for particles below 1 micron, but it is still able to show “general structures of colloid system”. 2. They are not dialyzed –> Colloidal particles will not be separated by membranes (like bladder or parchment paper), because they will not diffuse through a membrane. 3. They show permanent Brownian motions – mostly particles smaller than 100nm are able to do strong Brownian motion. 4. They show Tyndall effect – visible light scattering by the colloidal particles. 5. They may coagulate –> colloid particles become agglomerated. 7 Tyndall Effect This is light scattering by colloidal solution (for example by dust, fog, milk,etc.). When light beam passes through the colloidal dispersion it is scattered and therefore is visible. When light beam passes through the solution, like water, it is not scatter and therefore it cannot be seen. Intensity of this phenomena is larger when difference between light scattering of dispersive medium is larger then light scattering of dispersed phase. 8 Solutions vs Colloids The Tyndall Effect True Solution e.g. water Colloidal mixture, e.g. milk 9 The Tyndall Effect 10 CLASSIFICATION OF COLLOIDAL SYSTEMS DEPENDING ON : I. STATE OF DISPERSING AND DISPERSED PHASE Disperssed Disperssing phase COLLOID EXAMPLE phase Gas Gas - - Liquid Gas Aerosol liquid Fog, clouds, vapors Solid Gas Aerosol solid Smoke, dust Gas Liquid Foam Foam: soap, beer Liquid Liquid Emulsion Creams, nail polish, milk, mayonese, butter Solid Liquid Zol Polymer solutions Gas Solid Foam Pumice, styrofoam Liquid Solid Emulsion solid Gels, opal Solid Solid Zol solid Glass rubin, colour cristals 11 CLASSIFICATION OF COLLOIDAL SYSTEM : II. Size of colloidal particles: ➢ monodispersive (particles of dispersed phase have the same dimensions) ➢ polydispersive (particles of dispersed phase have different dimensions) III. Affinity of dispersed phase to dispersing medium : •liophilic colloids – they have large affinity to solvent particles; colloidal particles are surrounded by solvent particles • liophobic colloids – they have small affinity to solvent and adsorb on the surface of particles large quantities of one type of ions 12 CLASSIFICATION OF COLLOIDAL SYSTEM DEPENDS ON (cont.) IV. Quality of dispersed phase: Emulsions – the dispersed phase is of nonpolar character (e.g. lipids) and does not have affinity to dispersion medium (e.g. water). Emulsions have hydrophobic character and are also called suspensions or irreversible colloids. • In living organisms example of emulssions are lipids. Small particles of lipids can be dispersed in water thanks to the compounds called emulsifiers. Emulsifier – this is compund which can be „dissolved” in both – dispersed phase and dispersion medium. For example, consumed fats are emulsified by bile acids contained in bile. They have ability to decrease surface tension, like soap in water. 13 AgI micelle structure precipitated with excess of KI nucleus LAYER Nucleus of colloidal molecule +adsorbtion layer core DIFFUSION micelle 14 COLLOIDS STRUCTURE Hydrophobic micell are mostly built by oxides, sulphates, hydroxides of heavy metals Hydrophilic colloids are built usually by large molecules such as : proteins. Their stability is due to the presence of water molecules adsorbed on their surface. 15 Coagulation (1) COAGULATION – it is an ability of colloid particles to combine with each other and form larger structures called agregates. After reaching appropriate size they loose ability „to flow” and they sediment on the bottom. Coagulation can be caused by: 1. radioactivity– beta ray 2. heating – coagulation of protein (egg) 3. evaporation or freezing of dispersive medium 4. dehydration, for example by using acetone, alcohol 5. addition of electrolite to colloid 16 Coagulation (2) Peptization – process opposite to coagulation – breaking coagulate and return from coagulate to colloid. SOL coagulation GEL peptization 17 Coagulation (3) Hydrophilic colloid (reversible) – takes place when water coat has been removed Hydrophobic colloids (irreversible) – takes palce when electrical charge present on the surface becomes neutralized. 18 COLLOIDS HYDROPHOBIC HYDROPHILIC Strongly hydrated salts Salts with multivalance cations coagulate Water particles 19 Coagulation (4) Conditions for salting out of protein • Proteins are easiest to be salted out in their isoelectric point (pI) because they do not posses any electrical charge, they attract themselves strongly and create aggregates, which leads to precipitation (lack of electrical charge helps molecules to aggregate, which allows them to precipitate from solution). • In pH different from pI, protein due to presence of the surface charge can exist in solution despite not having water coat ( they behave similar as hydrophobic colloids) • Addition of small amount of neutralizing electrical charge ions leads to protein precipitation. Such protein does not posses either electrical charge or water coat. 20 Conditions for salting out protein from solution Protein ion Protein cation Protein in pI Base addition Acid addition pH increase pH decrease dyhadration Charge lost due to charge lost due cation addition to anion addition precipitate Protein cation Protein anion suspenoid 21 Salting out of proteins • Proteins are easy to salt-out in isoelectric point (pI) and in this state they easily sediment as larger aggregates. [Isoelctric point it is pH at which proteins have no electrical charge]. • In pH different than pI protein can exist in solution despite having no hydrophilic coat. http://elte.prompt.hu/sites/default/files/tananyagok/IntroductionToPracticalBiochemistry/ch05s04. 22 html PROTECTIVE ROLE OF HYDRPHILIC COLLOIDS ON HYDROPHOBIC COLLOIDS Hydrophilic colloids show higher stability than hydrophobic colloids, because of two stabilizing factors: • hydration layer • sometimes - particles have the same charge (which can be result of dissotiation of acidic or basic groups being present in colloidal particle) Hydrophilic colloids are acting protective on hydrophobic colloids – addition of hydrophilic colloid to hydrophobic is causing creation of stable system from which it is difficult to precipitae suspended particles (e.g. small amount of protein added to colloidal gold suspension protects it from coagulation). Protective role of colloid can be determined quantitatively by providing gold number ( gold number it is the smallest amount of miligrams of protective colloid in respect to pure substance which is able to protect 10cm3 0,1% of formaldehyde gold zol, against color change from red to purple after addition of 1cm3 10% NaCl ) 23 Colloids in fluid therapy (1) Fluid therapy (1): treatment consisting of fluid intake (usually intravenous, intraarterial or subcutaneous) often used in hospital as well as emergency 24 Colloids in fluid therapy (2) Fluid therapy (2): compensating fluid deficiency is one of the most urgent tasks in the treatment of critically ill patients with hypovolemia ✓ hypovolemia - a decrease in intravascular volume, resulting in insufficient functioning of the normal mechanisms to hold fluid in the vascular bed - may exists as a reduced, normal or increased extracellular
Recommended publications
  • Effect of Electrolyte Addition on the Colloidal Stability of Aqueous Zeolite Sols
    First published in: 2550 Helvetica Chimica Acta ± Vol. 84 (2001) Effect of Electrolyte Addition on the Colloidal Stability of Aqueous Zeolite Sols by Torsten Mäurer and Bettina Kraushaar-Czarnetzki*1) Institute of Chemical Process Engineering CVT, University of Karlsruhe (TH), D-76128 Karlsruhe Dedicated to Professor Andre M. Braun on the occasion of his 60th birthday Recovery of zeolites from aqueous media can be a very difficult operation, when the crystals have colloidal dimensions. The solid-liquid separation can be facilitated by processing at the respective isoelectric point (IEP) where the sol is unstable and the crystals form aggregates. The addition of salts results in a further improvement, because the zeolite agglomerates become larger, and the pH range of flocculation is broadened. This wider operational window, in particular, is of importance for the recovery of zeolites that would dealuminate or collapse at their respective IEP. Introduction. ± Handling of aqueous sols or suspensions of zeolite crystals is a frequently recurring operation in the manufacturing of zeolite-based catalysts or adsorbents. Starting with the zeolite synthesis in aqueous medium, the typical workup comprises repeated ion exchange in aqueous solutions and, finally, a wet shaping process during which bodies of suitable size, shape, strength, pore texture, and site distribution must be formed. Large agglomerates of crystals are beneficial, when zeolites must be recovered from their mother liquor or from ion-exchange solutions, whereas isolated zeolite single crystals, dispersed in the porous matrix of a shaped particle, are highly desirable when catalytic properties are to be optimized. These opposing require- ments for efficient solid-liquid separations, on one hand, and optimum product quality, on the other hand, demand for means to control the particle size in a reversible manner.
    [Show full text]
  • Lecture Notes: BCS Theory of Superconductivity
    Lecture Notes: BCS theory of superconductivity Prof. Rafael M. Fernandes Here we will discuss a new ground state of the interacting electron gas: the superconducting state. In this macroscopic quantum state, the electrons form coherent bound states called Cooper pairs, which dramatically change the macroscopic properties of the system, giving rise to perfect conductivity and perfect diamagnetism. We will mostly focus on conventional superconductors, where the Cooper pairs originate from a small attractive electron-electron interaction mediated by phonons. However, in the so- called unconventional superconductors - a topic of intense research in current solid state physics - the pairing can originate even from purely repulsive interactions. 1 Phenomenology Superconductivity was discovered by Kamerlingh-Onnes in 1911, when he was studying the transport properties of Hg (mercury) at low temperatures. He found that below the liquifying temperature of helium, at around 4:2 K, the resistivity of Hg would suddenly drop to zero. Although at the time there was not a well established model for the low-temperature behavior of transport in metals, the result was quite surprising, as the expectations were that the resistivity would either go to zero or diverge at T = 0, but not vanish at a finite temperature. In a metal the resistivity at low temperatures has a constant contribution from impurity scattering, a T 2 contribution from electron-electron scattering, and a T 5 contribution from phonon scattering. Thus, the vanishing of the resistivity at low temperatures is a clear indication of a new ground state. Another key property of the superconductor was discovered in 1933 by Meissner.
    [Show full text]
  • Supercritical Fluid Extraction of Positron-Emitting Radioisotopes from Solid Target Matrices
    XA0101188 11. United States of America Supercritical Fluid Extraction of Positron-Emitting Radioisotopes From Solid Target Matrices D. Schlyer, Brookhaven National Laboratory, Chemistry Department, Upton, Bldg. 901, New York 11973-5000, USA Project Description Supercritical fluids are attractive as media for both chemical reactions, as well as process extraction since their physical properties can be manipulated by small changes in pressure and temperature near the critical point of the fluid. What is a supercritical fluid? Above a certain temperature, a vapor can no longer be liquefied regardless of pressure critical temperature - Tc supercritical fluid r«gi on solid a u & temperature Fig. 1. Phase diagram depicting regions of solid, liquid, gas and supercritical fluid behavior. The critical point is defined by a critical pressure (Pc) and critical temperature (Tc) for a particular substance. Such changes can result in drastic effects on density-dependent properties such as solubility, refractive index, dielectric constant, viscosity and diffusivity of the fluid[l,2,3]. This suggests that pressure tuning of a pure supercritical fluid may be a useful means to manipulate chemical reactions on the basis of a thermodynamic solvent effect. It also means that the solvation properties of the fluid can be precisely controlled to enable selective component extraction from a matrix. In recent years there has been a growing interest in applying supercritical fluid extraction to the selective removal of trace metals from solid samples [4-10]. Much of the work has been done on simple systems comprised of inert matrices such as silica or cellulose. Recently, this process as been expanded to environmental samples as well [11,12].
    [Show full text]
  • Equation of State and Phase Transitions in the Nuclear
    National Academy of Sciences of Ukraine Bogolyubov Institute for Theoretical Physics Has the rights of a manuscript Bugaev Kyrill Alekseevich UDC: 532.51; 533.77; 539.125/126; 544.586.6 Equation of State and Phase Transitions in the Nuclear and Hadronic Systems Speciality 01.04.02 - theoretical physics DISSERTATION to receive a scientific degree of the Doctor of Science in physics and mathematics arXiv:1012.3400v1 [nucl-th] 15 Dec 2010 Kiev - 2009 2 Abstract An investigation of strongly interacting matter equation of state remains one of the major tasks of modern high energy nuclear physics for almost a quarter of century. The present work is my doctor of science thesis which contains my contribution (42 works) to this field made between 1993 and 2008. Inhere I mainly discuss the common physical and mathematical features of several exactly solvable statistical models which describe the nuclear liquid-gas phase transition and the deconfinement phase transition. Luckily, in some cases it was possible to rigorously extend the solutions found in thermodynamic limit to finite volumes and to formulate the finite volume analogs of phases directly from the grand canonical partition. It turns out that finite volume (surface) of a system generates also the temporal constraints, i.e. the finite formation/decay time of possible states in this finite system. Among other results I would like to mention the calculation of upper and lower bounds for the surface entropy of physical clusters within the Hills and Dales model; evaluation of the second virial coefficient which accounts for the Lorentz contraction of the hard core repulsing potential between hadrons; inclusion of large width of heavy quark-gluon bags into statistical description.
    [Show full text]
  • 101 Lime Solvent
    Sure Klean® CLEANING & PROTECTIVE TREATMENTS 101 Lime Solvent Sure Klean® 101 Lime Solvent is a concentrated acidic cleaner for dark-colored brick and tile REGULATORY COMPLIANCE surfaces which are not subject to metallic oxidation. VOC Compliance Safely removes excess mortar and construction dirt. Sure Klean® 101 Lime Solvent is compliant with all national, state and district VOC regulations. ADVANTAGES • Removes construction dirt and excess mortar with TYPICAL TECHNICAL DATA simple cold water rinse. Clear, brown liquid • Removes efflorescence from new brick and new FORM Pungent odor stone construction. SPECIFIC GRAVITY 1.12 • Safer than muriatic acid on colored mortar and dark-colored new masonry surfaces. pH 0.50 @ 1:6 dilution • Proven effective since 1954. WT/GAL 9.39 lbs Limitations ACTIVE CONTENT not applicable • Not generally effective in removal of atmospheric TOTAL SOLIDS not applicable stains and black carbon found on older masonry VOC CONTENT not applicable surfaces. Use the appropriate Sure Klean® FLASH POINT not applicable restoration cleaner to remove atmospheric staining from older masonry surfaces. FREEZE POINT <–22° F (<–30° C) • Not for use on polished natural stone. SHELF LIFE 3 years in tightly sealed, • Not for use on treated low-E glass; acrylic and unopened container polycarbonate sheet glazing; and glazing with surface-applied reflective, metallic or other synthetic coatings and films. SAFETY INFORMATION Always read full label and SDS for precautionary instructions before use. Use appropriate safety equipment and job site controls during application and handling. 24-Hour Emergency Information: INFOTRAC at 800-535-5053 Product Data Sheet • Page 1 of 4 • Item #10010 – 102715 • ©2015 PROSOCO, Inc.
    [Show full text]
  • Solvent Effects on the Thermodynamic Functions of Dissociation of Anilines and Phenols
    University of Wollongong Research Online University of Wollongong Thesis Collection 1954-2016 University of Wollongong Thesis Collections 1982 Solvent effects on the thermodynamic functions of dissociation of anilines and phenols Barkat A. Khawaja University of Wollongong Follow this and additional works at: https://ro.uow.edu.au/theses University of Wollongong Copyright Warning You may print or download ONE copy of this document for the purpose of your own research or study. The University does not authorise you to copy, communicate or otherwise make available electronically to any other person any copyright material contained on this site. You are reminded of the following: This work is copyright. Apart from any use permitted under the Copyright Act 1968, no part of this work may be reproduced by any process, nor may any other exclusive right be exercised, without the permission of the author. Copyright owners are entitled to take legal action against persons who infringe their copyright. A reproduction of material that is protected by copyright may be a copyright infringement. A court may impose penalties and award damages in relation to offences and infringements relating to copyright material. Higher penalties may apply, and higher damages may be awarded, for offences and infringements involving the conversion of material into digital or electronic form. Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong. Recommended Citation Khawaja, Barkat A., Solvent effects on the thermodynamic functions of dissociation of anilines and phenols, Master of Science thesis, Department of Chemistry, University of Wollongong, 1982.
    [Show full text]
  • Lecture 5 Non-Aqueous Phase Liquid (NAPL) Fate and Transport
    Lecture 5 Non-Aqueous Phase Liquid (NAPL) Fate and Transport Factors affecting NAPL movement Fluid properties: Porous medium: 9 Density Permeability 9 Interfacial tension Pore size 9 Residual saturation Structure Partitioning properties Solubility Ground water: Volatility and vapor density Water content 9 Velocity Partitioning processes NAPL can partition between four phases: NAPL Gas Solid (vapor) Aqueous solution Water to gas partitioning (volatilization) Aqueous ↔ gaseous Henry’s Law (for dilute solutions) 3 Dimensionless (CG, CW in moles/m ) C G = H′ CW Dimensional (P = partial pressure in atm) P = H CW Henry’s Law Constant H has dimensions: atm m3 / mol H’ is dimensionless H’ = H/RT R = gas constant = 8.20575 x 10-5 atm m3/mol °K T = temperature in °K NAPL to gas partitioning (volatilization) NAPL ↔ gaseous Raoult’s Law: CG = Xt (P°/RT) Xt = mole fraction of compound in NAPL [-] P° = pure compound vapor pressure [atm] R = universal gas constant [m3-atm/mole/°K] T = temperature [°K] Volatility Vapor pressure P° is measure of volatility P° > 1.3 x 10-3 atm → compound is “volatile” 1.3 x 10-3 > P° > 1.3 x 10-13 atm → compound is “semi-volatile” Example: equilibrium with benzene P° = 76 mm Hg at 20°C = 0.1 atm R = 8.205 x 10-5 m3-atm/mol/°K T = 20°C (assumed) = 293°K Assume 100% benzene, mole fraction Xt = 1 3 CG = Xt P°/(RT) = 4.16 mol/m Molecular weight of benzene, C6H6 = 78 g/mol 3 3 CG = 4.16 mol/m × 78 g/mol = 324 g/m = 0.32 g/L 6 CG = 0.32 g/L x 24 L/mol / (78 g/mol) x 10 = 99,000 ppmv One mole of ideal gas = 22.4 L at STP (1 atm, 0 C), Corrected to 20 C: 293/273*22.4 = 24.0 L/mol Gas concentration in equilibrium with pure benzene NAPL Example: equilibrium with gasoline Gasoline is complex mixture – mole fraction is difficult to determine and varies Benzene = 1 to several percent (Cline et al., 1991) Based on analysis reported by Johnson et al.
    [Show full text]
  • Colloid Stability 3 Kinetics of Coagulation Lyophobic Dispersions Are Never Stable in the Thermodynamic Sense, but Exhibit Some Degree of Instability
    1 المحاضرة الثالثة – ثالثة علوم كيمياء Colloid stability 3 Kinetics of coagulation Lyophobic dispersions are never stable in the thermodynamic sense, but exhibit some degree of instability. From a practical point of view, the word 'stable' is often loosely used to describe a dispersion in which the coagulation rate is slow in relation to its required 'shelf life'. The rate at which a sol coagulates depends on the frequency with which the particles encounter one another and the probability that their thermal energy is sufficient to overcome the repulsive potential energy barrier to coagulation when these encounters take place. The rate at which particles aggregate is given by dn k n2 dt 2 Where n is the number of particles per unit volume of sol at time t, and k2 is a second-order rate constant, Integrating, and putting n - no at t = 0, 1 1 gives kt (16) n no During the course of coagulation k2 usually decreases, and sometimes an equilibrium state is reached with the sol only partially coagulated. This may be a consequence of the height of the repulsion energy barrier increasing with increasing particle size. In experimental tests of stability theories it is usual to restrict measurements to the early stages of coagulation (where the aggregating mechanism is most straightforward), using moderately dilute sols. The particle concentration during early stages of coagulation can be determined directly, by visual particle counting, or indirectly, from turbidity (spectrophotometric or light scattering) measurements. If necessary, coagulation in an aliquot of sol can be halted prior to 2 examination by the addition of a small amount of a stabilizing agent, such as gelatin.
    [Show full text]
  • Introduction to Unconventional Superconductivity Manfred Sigrist
    Introduction to Unconventional Superconductivity Manfred Sigrist Theoretische Physik, ETH-Hönggerberg, 8093 Zürich, Switzerland Abstract. This lecture gives a basic introduction into some aspects of the unconventionalsupercon- ductivity. First we analyze the conditions to realized unconventional superconductivity in strongly correlated electron systems. Then an introduction of the generalized BCS theory is given and sev- eral key properties of unconventional pairing states are discussed. The phenomenological treatment based on the Ginzburg-Landau formulations provides a view on unconventional superconductivity based on the conceptof symmetry breaking.Finally some aspects of two examples will be discussed: high-temperature superconductivity and spin-triplet superconductivity in Sr2RuO4. Keywords: Unconventional superconductivity, high-temperature superconductivity, Sr2RuO4 INTRODUCTION Superconductivity remains to be one of the most fascinating and intriguing phases of matter even nearly hundred years after its first observation. Owing to the breakthrough in 1957 by Bardeen, Cooper and Schrieffer we understand superconductivity as a conden- sate of electron pairs, so-called Cooper pairs, which form due to an attractive interaction among electrons. In the superconducting materials known until the mid-seventies this interaction is mediated by electron-phonon coupling which gises rise to Cooper pairs in the most symmetric form, i.e. vanishing relative orbital angular momentum and spin sin- glet configuration (nowadays called s-wave pairing). After the introduction of the BCS concept, also studies of alternative pairing forms started. Early on Anderson and Morel [1] as well as Balian and Werthamer [2] investigated superconducting phases which later would be identified as the A- and the B-phase of superfluid 3He [3]. In contrast to the s-wave superconductors the A- and B-phase are characterized by Cooper pairs with an- gular momentum 1 and spin-triplet configuration.
    [Show full text]
  • Light Interaction with Matter Lesson Plan
    Penn State RET in Interdisciplinary Materials Teacher’s Preparatory Guide : GILBERT AMADI Lab Title: Interaction of Light with Matter Purpose: In this unit, students are expected to learn: • How the light can be absorbed or scattered by small objects such as nanoparticles; • How light can be used to monitor the absorption and scattering of solutions; • How to compare light absorption, fluorescence, and light scattering; and • Color sensitivity of the absorption, scattering and fluorescence of a materials. Learning objectives: To recognize the experimental evidence for the wave nature of light. To understand that light travels with different speeds in different media To know the difference between turbidity and light absorbance To explore how different wavelengths interfere with different solution media To understand how blue, green and red) light from hand-hold laser pointers interact with different materials, including nanoparticles, fluorescence dye and milk. To understand the difference between absorbance and fluorescence Time required: 2-3 periods Level: High school National Science Education Standards : 11-12th grade Content Standard A • Abilities necessary to do scientific inquiry Content Standard B • Structure and properties of Light • Light Interaction with matter • Transfer of Energy • Light transmission, absorption, and scattering. • Energy as a property of many substances and its association with heat. • Light, electricity, mechanical motion, sound, atomic, nuclei, and the nature of a chemical • Energy transfer. This
    [Show full text]
  • Solvent-Tunable Binding of Hydrophilic and Hydrophobic Guests by Amphiphilic Molecular Baskets Yan Zhao Iowa State University, [email protected]
    Chemistry Publications Chemistry 8-2005 Solvent-Tunable Binding of Hydrophilic and Hydrophobic Guests by Amphiphilic Molecular Baskets Yan Zhao Iowa State University, [email protected] Eui-Hyun Ryu Iowa State University Follow this and additional works at: http://lib.dr.iastate.edu/chem_pubs Part of the Chemistry Commons The ompc lete bibliographic information for this item can be found at http://lib.dr.iastate.edu/ chem_pubs/197. For information on how to cite this item, please visit http://lib.dr.iastate.edu/ howtocite.html. This Article is brought to you for free and open access by the Chemistry at Iowa State University Digital Repository. It has been accepted for inclusion in Chemistry Publications by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Solvent-Tunable Binding of Hydrophilic and Hydrophobic Guests by Amphiphilic Molecular Baskets Abstract Responsive amphiphilic molecular baskets were obtained by attaching four facially amphiphilic cholate groups to a tetraaminocalixarene scaffold. Their binding properties can be switched by solvent changes. In nonpolar solvents, the molecules utilize the hydrophilic faces of the cholates to bind hydrophilic molecules such as glucose derivatives. In polar solvents, the molecules employ the hydrophobic faces of the cholates to bind hydrophobic guests. A water-soluble basket can bind polycyclic aromatic hydrocarbons including anthracene, pyrene, and perylene. The binding free energy (−ΔG) ranges from 5 to 8 kcal/mol and is directly proportional to the surface area of the aromatic hosts. Binding of both hydrophilic and hydrophobic guests is driven by solvophobic interactions. Disciplines Chemistry Comments Reprinted (adapted) with permission from Journal of Organic Chemistry 70 (2005): 7585, doi:10.1021/ jo051127f.
    [Show full text]
  • I. the Nature of Solutions
    Solutions The Nature of Solutions Definitions Solution - homogeneous mixture Solute - substance being dissolved Solvent - present in greater amount Types of Solutions SOLUTE – the part of a Solute Solvent Example solution that is being dissolved (usually the solid solid ? lesser amount) solid liquid ? SOLVENT – the part of a solution that gas solid ? dissolves the solute (usually the greater liquid liquid ? amount) gas liquid ? Solute + Solvent = Solution gas gas ? Is it a Solution? Homogeneous Mixture (Solution) Tyndall no Effect? Solution Is it a Solution? Solution • homogeneous • very small particles • no Tyndall effect • particles don’t settle • Ex: •rubbing alcohol Is it a Solution? Homogeneous Mixture (Solution) Tyndall no Effect? yes Solution Suspension, Colloid, or Emulsion Will mixture separate if allowed to stand? no Colloid (very fine solid in liquid) Is it a Solution? Colloid • homogeneous • very fine particles • Tyndall effect • particles don’t settle • Ex: •milk Is it a Solution? Homogeneous Mixture (Solution) Tyndall Effect? no yes Solution Suspension, Colloid, or Emulsion Will mixture separate if allowed to stand? no yes Colloid Suspension or Emulsion Solid or liquid particles? solid Suspension (course solid in liquid) Is it a Solution? Suspension • homogeneous • large particles • Tyndall effect • particles settle if given enough time • Ex: • Pepto-Bismol • Fresh-squeezed lemonade Is it a Solution? Homogeneous Mixture (Solution) Tyndall no Effect? yes Solution Suspension, Colloid, or Emulsion Will mixture separate if allowed to stand? no yes Colloid Suspension or Emulsion Solid or liquid particles? solid liquid Suspension (course solid in liquid) Emulsion (liquid in liquid) Is it a Solution? Emulsion • homogeneous • mixture of two immiscible liquids • Tyndall effect • particles settle if given enough time • Ex: • Mayonnaise Pure Substances vs.
    [Show full text]