DOCSLIB.ORG

Note Structures Enthalpy – ∆H – Heat Energy ∆H Fusion and Vaporization

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Note Structures Enthalpy – ∆H – Heat Energy ∆H Fusion and Vaporization 10.4 Phase Changes Phase Changes - note structures fusion (melting): s l freezing: l s vaporization: l g condensation: g l sublimation: s g deposition: g s Enthalpy – DH – heat energy DH fusion and vaporization DH + is endothermic DHfus = heat of fusion = energy to convert solid Heat is added, required to liquid, energy needed to melt DH – is exothermic DHvap = heat of vaporization = energy to Heat is released, heat exits convert liquid to gas, energy needed to boil Ignore DS and DG – we do that in CHM 152 Look at Figure 10.9 Heating Curve Why does T The temp stays constant during melting and stay constant boiling because all the energy is going into during fusion breaking the IMF that is holding the solid / (melting) and liquid together. vaporization? Note melting point and freezing point are the How is energy same temp. Boiling point and condensing used between A point are also the same temp. and B, C and D? mp = fp for water = 0oC Figure 11.38 bp = cp for water = 100oC Water 1 Ice 1 Temp chgs of state 8 1 answers 10.5 Evap, VP and bp Xe because it is bigger, more electrons, more Boiling – quick heating of a liquid to break IMF London force than Kr, so higher bp and turn liquid into gas. Temperature where this occurs is the bp. CH3Cl because it is polar and CH4 is nonpolar Evaporation – no heat added, very slow, NH3 because it has the stronger H bonding forces holding it together surface molecules / atoms “pop” out and float away. Only the higher kinetic energy ones pop out, so this lowers the KE of the sample left behind, thus it feels cooler. This occurs at lower temp than the bp. 10.5 Vapor Pressure Vaporizing liquid VP Liquid evaporates, gaseous molecules exert a A liquid with a lower IMF will actually have a pressure (vapor pressure) in a closed container higher VP because the molecules evaporate that can be measured as shown below easier, so more pressure A liquid with a higher IMF will have a lower VP because it is harder for the molecules to go to the gas phase, they prefer to stay liquid, so less gas, less pressure. So as IMF increase, VP decrease As IMF increase, bp increase Figure 10.11 10.6 Kinds of Solids Kinds of Solids Amorphous: random arrangement (rubber) Molecular (left): covalent molecules in an ordered arrangement (sucrose, ice); intermolecular forces hold Ionic: ordered arrangement of ions (NaCl), has molecules together, low mp ionic bonds, high mp Covalent network (right): atoms connected by covalent bonds in all directions in 3D array (quartz, diamonds), See Figure 10.14 high mp 2 Kinds of solids 10.11 Phase Diagram Atomic Phase diagrams Metallic – has metallic bonds, mp varies, Features of a phase diagram: conducts well, solid gold, sodium, silver, etc Triple point: temperature and pressure at which all three phases (s, l, and g) exist and are in equilibrium Vaporization curve: equilibrium between liquid and gas Melting curve: equilibrium between solid and liquid Normal melting point: melting point at 1 atm Normal boiling point: boiling point at 1 atm Label Phase diagrams 27 10.11 Phase Diagram: Water Low Temp Boil Critical Temperature and Pressure Critical point: liquid and gas phases are indistinguishable Critical temperature, Tc : highest temperature at which a substance can exist as a liquid Phase (cannot be liquified) no matter how much Diagram pressure is applied Critical pressure, Tp : minimum pressure that must be applied to bring about liquefaction at the critical temperature http://www.chm.davidson.edu/ChemistryApplets/PhaseChanges/PhaseDiagram.html Phase Diagram: Carbon Dioxide Phase Dia- Grams: H2O Worked Ex. 10.11, and CO2 Problems 10.17, 10.18, 19 30 3 .
Load more

Recommended publications
  • 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 for Benzene for Temperatures from the Melting Line up to 725 K with Pressures up to 500 Mpa†
    High Temperatures-High Pressures, Vol. 41, pp. 81–97 ©2012 Old City Publishing, Inc. Reprints available directly from the publisher Published by license under the OCP Science imprint, Photocopying permitted by license only a member of the Old City Publishing Group Equation of state for benzene for temperatures from the melting line up to 725 K with pressures up to 500 MPa† MONIKA THOL ,1,2,* ERIC W. Lemm ON 2 AND ROLAND SPAN 1 1Thermodynamics, Ruhr-University Bochum, Universitaetsstrasse 150, 44801 Bochum, Germany 2National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA Received: December 23, 2010. Accepted: April 17, 2011. An equation of state (EOS) is presented for the thermodynamic properties of benzene that is valid from the triple point temperature (278.674 K) to 725 K with pressures up to 500 MPa. The equation is expressed in terms of the Helmholtz energy as a function of temperature and density. This for- mulation can be used for the calculation of all thermodynamic properties. Comparisons to experimental data are given to establish the accuracy of the EOS. The approximate uncertainties (k = 2) of properties calculated with the new equation are 0.1% below T = 350 K and 0.2% above T = 350 K for vapor pressure and liquid density, 1% for saturated vapor density, 0.1% for density up to T = 350 K and p = 100 MPa, 0.1 – 0.5% in density above T = 350 K, 1% for the isobaric and saturated heat capaci- ties, and 0.5% in speed of sound. Deviations in the critical region are higher for all properties except vapor pressure.
    [Show full text]
  • Geometrical Vortex Lattice Pinning and Melting in Ybacuo Submicron Bridges Received: 10 August 2016 G
    www.nature.com/scientificreports OPEN Geometrical vortex lattice pinning and melting in YBaCuO submicron bridges Received: 10 August 2016 G. P. Papari1,*, A. Glatz2,3,*, F. Carillo4, D. Stornaiuolo1,5, D. Massarotti5,6, V. Rouco1, Accepted: 11 November 2016 L. Longobardi6,7, F. Beltram2, V. M. Vinokur2 & F. Tafuri5,6 Published: 23 December 2016 Since the discovery of high-temperature superconductors (HTSs), most efforts of researchers have been focused on the fabrication of superconducting devices capable of immobilizing vortices, hence of operating at enhanced temperatures and magnetic fields. Recent findings that geometric restrictions may induce self-arresting hypervortices recovering the dissipation-free state at high fields and temperatures made superconducting strips a mainstream of superconductivity studies. Here we report on the geometrical melting of the vortex lattice in a wide YBCO submicron bridge preceded by magnetoresistance (MR) oscillations fingerprinting the underlying regular vortex structure. Combined magnetoresistance measurements and numerical simulations unambiguously relate the resistance oscillations to the penetration of vortex rows with intermediate geometrical pinning and uncover the details of geometrical melting. Our findings offer a reliable and reproducible pathway for controlling vortices in geometrically restricted nanodevices and introduce a novel technique of geometrical spectroscopy, inferring detailed information of the structure of the vortex system through a combined use of MR curves and large-scale simulations. Superconductors are materials in which below the superconducting transition temperature, Tc, electrons form so-called Cooper pairs, which are bosons, hence occupying the same lowest quantum state1. The wave function of this Cooper condensate has a fixed phase. Hence, by virtue of the uncertainty principle, the number of Cooper pairs in the condensate is undefined.
    [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]
  • Two-Dimensional Vortex Lattice Melting Superconducting Length
    Two-Dimensional Vortex Lattice Melting Superconducting Length-Scales and Vortex Lattices Flux Motion Melting Concepts Journal Paper Presentation: “Melting of the Vortex Lattice Through the Hexatic Phase in an MoGe3 Thin Film” 1 Repulsive Interaction Between Vortices Vortex Lattice 2 Vortex Melting in Superconducting Nb 3 (For 3D clean Type II superconductor) Vortex Lattice Expands on Freezing (Like Ice) Jump in the Magnetization 4 Melting Concepts 3D Solid Liquid Lindemann Criterion (∆r)2 ↵a 1st Order Transition ⇡ p 5 6 Journal Presentation Motivation/Context Results Interpretation Questions/Ideas for Future Work (aim for 30-45 mins) Please check the course site about the presentation schedule No class on The April 8, 15 Make-Ups on Ms April 12, 19 (Weekly Discussion to be Rescheduled) 7 First Definitive Observation of the Hexatic Phase in a Superconducting Film (with 8 thanks to Indranil Roy and Pratap Raychaudhuri) Two Dimensional Melting (BKT + HNY theory) 9 10 Hexatics have been observed in 2D colloidal systems Why not in the Melting of the Vortex Phase of Superconducting Films ?? 11 Quest for the Hexatic Liquid Phase in ↵ MoGe − Why Not Before ?? Orientational Coupling Hexatic Glass !! between Atomic and Vortex Lattices Solution: Amorphous Superconductor (no lattice effect) Very Weak Pinning BCS-Type Superconductor 12 Scanning Tunneling Spectroscopy (STS) Magnetotransport 13 14 15 16 17 The Resulting Phase Diagram 18 Summary First Observation of Hexatic Fluid Phase in a 2D Superconducting Film Pinning Significantly Weaker than in Previous Studies STS (imaging) Magnetotransport (“shear”) Questions/Ideas for the Future Size-Dependence of Hexatic Order Parameter ?? Low T limit of the Hexatic Fluid: Quantum Vortex Fluid ?? What happens in Layered Films ?? 19 20.
    [Show full text]
  • Sodium Spinor Bose-Einstein Condensates
    SODIUM SPINOR BOSE-EINSTEIN CONDENSATES: ALL-OPTICAL PRODUCTION AND SPIN DYNAMICS By JIEJIANG BachelorofScienceinOpticalInformationScience UniversityofShanghaiforScienceandTechnology Shanghai,China 2009 SubmittedtotheFacultyofthe GraduateCollegeof OklahomaStateUniversity inpartialfulfillmentof therequirementsfor theDegreeof DOCTOROFPHILOSOPHY December,2015 COPYRIGHT c By JIE JIANG December, 2015 SODIUM SPINOR BOSE-EINSTEIN CONDENSATES: ALL-OPTICAL PRODUCTION AND SPIN DYNAMICS Dissertation Approved: Dr. Yingmei Liu Dissertation Advisor Dr. Albert T. Rosenberger Dr. Gil Summy Dr. Weili Zhang iii ACKNOWLEDGMENTS I would like to first express my sincere gratitude to my thesis advisor Dr. Yingmei Liu, who introduced ultracold quantum gases to me and guided me throughout my PhD study. I am greatly impressed by her profound knowledge, persistent enthusiasm and love in BEC research. It has been a truly rewarding and privilege experience to perform my PhD study under her guidance. I also want to thank my committee members, Dr. Albert Rosenberger, Dr. Gil Summy, and Dr. Weili Zhang for their advice and support during my PhD study. I thank Dr. Rosenberger for the knowledge in lasers and laser spectroscopy I learnt from him. I thank Dr. Summy for his support in the department and the academic exchange with his lab. Dr. Zhang offered me a unique opportunity to perform microfabrication in a cleanroom, which greatly extended my research experience. During my more than six years study at OSU, I had opportunities to work with many wonderful people and the team members in Liu’s lab have been providing endless help for me which is important to my work. Many thanks extend to my current colleagues Lichao Zhao, Tao Tang, Zihe Chen, and Micah Webb as well as our former members Zongkai Tian, Jared Austin, and Alex Behlen.
    [Show full text]
  • Melting of Lamellar Phases in Temperature Sensitive Colloid-Polymer Suspensions
    PHYSICAL REVIEW LETTERS week ending VOLUME 93, NUMBER 5 30 JULY 2004 Melting of Lamellar Phases in Temperature Sensitive Colloid-Polymer Suspensions A. M. Alsayed, Z. Dogic, and A. G. Yodh Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6396, USA (Received 10 March 2004; published 29 July 2004) We prepare a novel suspension composed of rodlike fd virus and thermosensitive polymer poly(N-isopropylacrylamide) whose phase diagram is temperature and concentration dependent. The system exhibits a rich variety of stable and metastable phases, and provides a unique opportunity to directly observe melting of lamellar phases and single lamellae. Typically, lamellar phases swell with increasing temperature before melting into the nematic phase. The highly swollen lamellae can be superheated as a result of topological nucleation barriers that slow the formation of the nematic phase. DOI: 10.1103/PhysRevLett.93.057801 PACS numbers: 64.70.Md, 61.30.–v, 64.60.My Melting of three-dimensional (3D) crystals is among lamellar phases and coexisting isotropic or nematic the most ubiquitous phase transitions in nature [1]. In phases. contrast to freezing, melting of 3D crystals usually has The fd=NIPA solutions are unusual new materials no associated energy barrier. Bulk melting is initiated at a whose lamellar phases differ from those of amphiphilic premelted surface, which then acts as a heterogeneous molecules. The lamellar phase can swell considerably and nucleation site and eliminates the nucleation barrier for melt into a nematic phase, a transition almost never the phase transition [2]. In this Letter, we investigate observed in block-copolymer lamellar systems.
    [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]
  • Physical Changes
    How Matter Changes By Cindy Grigg Changes in matter happen around you every day. Some changes make matter look different. Other changes make one kind of matter become another kind of matter. When you scrunch a sheet of paper up into a ball, it is still paper. It only changed shape. You can cut a large, rectangular piece of paper into many small triangles. It changed shape and size, but it is still paper. These kinds of changes are called physical changes. Physical changes are changes in the way matter looks. Changes in size and shape, like the changes in the cut pieces of paper, are physical changes. Physical changes are changes in the size, shape, state, or appearance of matter. Another kind of physical change happens when matter changes from one state to another state. When water freezes and makes ice, it is still water. It has only changed its state of matter from a liquid to a solid. It has changed its appearance and shape, but it is still water. You can change the ice back into water by letting it melt. Matter looks different when it changes states, but it stays the same kind of matter. Solids like ice can change into liquids. Heat speeds up the moving particles in ice. The particles move apart. Heat melts ice and changes it to liquid water. Metals can be changed from a solid to a liquid state also. Metals must be heated to a high temperature to melt. Melting is changing from a solid state to a liquid state.
    [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]
  • Phase Diagrams a Phase Diagram Is Used to Show the Relationship Between Temperature, Pressure and State of Matter
    Phase Diagrams A phase diagram is used to show the relationship between temperature, pressure and state of matter. Before moving ahead, let us review some vocabulary and particle diagrams. States of Matter Solid: rigid, has definite volume and definite shape Liquid: flows, has definite volume, but takes the shape of the container Gas: flows, no definite volume or shape, shape and volume are determined by container Plasma: atoms are separated into nuclei (neutrons and protons) and electrons, no definite volume or shape Changes of States of Matter Freezing start as a liquid, end as a solid, slowing particle motion, forming more intermolecular bonds Melting start as a solid, end as a liquid, increasing particle motion, break some intermolecular bonds Condensation start as a gas, end as a liquid, decreasing particle motion, form intermolecular bonds Evaporation/Boiling/Vaporization start as a liquid, end as a gas, increasing particle motion, break intermolecular bonds Sublimation Starts as a solid, ends as a gas, increases particle speed, breaks intermolecular bonds Deposition Starts as a gas, ends as a solid, decreases particle speed, forms intermolecular bonds http://phet.colorado.edu/en/simulation/states- of-matter The flat sections on the graph are the points where a phase change is occurring. Both states of matter are present at the same time. In the flat sections, heat is being removed by the formation of intermolecular bonds. The flat points are phase changes. The heat added to the system are being used to break intermolecular bonds. PHASE DIAGRAMS Phase diagrams are used to show when a specific substance will change its state of matter (alignment of particles and distance between particles).
    [Show full text]