Which of These Factors Could Affect the Temperature at Which Water Boils?
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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. -
Determination of the Identity of an Unknown Liquid Group # My Name the Date My Period Partner #1 Name Partner #2 Name
Determination of the Identity of an unknown liquid Group # My Name The date My period Partner #1 name Partner #2 name Purpose: The purpose of this lab is to determine the identity of an unknown liquid by measuring its density, melting point, boiling point, and solubility in both water and alcohol, and then comparing the results to the values for known substances. Procedure: 1) Density determination Obtain a 10mL sample of the unknown liquid using a graduated cylinder Determine the mass of the 10mL sample Save the sample for further use 2) Melting point determination Set up an ice bath using a 600mL beaker Obtain a ~5mL sample of the unknown liquid in a clean dry test tube Place a thermometer in the test tube with the sample Place the test tube in the ice water bath Watch for signs of crystallization, noting the temperature of the sample when it occurs Save the sample for further use 3) Boiling point determination Set up a hot water bath using a 250mL beaker Begin heating the water in the beaker Obtain a ~10mL sample of the unknown in a clean, dry test tube Add a boiling stone to the test tube with the unknown Open the computer interface software, using a graph and digit display Place the temperature sensor in the test tube so it is in the unknown liquid Record the temperature of the sample in the test tube using the computer interface Watch for signs of boiling, noting the temperature of the unknown Dispose of the sample in the assigned waste container 4) Solubility determination Obtain two small (~1mL) samples of the unknown in two small test tubes Add an equal amount of deionized into one of the samples Add an equal amount of ethanol into the other Mix both samples thoroughly Compare the samples for solubility Dispose of the samples in the assigned waste container Observations: The unknown is a clear, colorless liquid. -
The Basics of Vapor-Liquid Equilibrium (Or Why the Tripoli L2 Tech Question #30 Is Wrong)
The Basics of Vapor-Liquid Equilibrium (Or why the Tripoli L2 tech question #30 is wrong) A question on the Tripoli L2 exam has the wrong answer? Yes, it does. What is this errant question? 30.Above what temperature does pressurized nitrous oxide change to a gas? a. 97°F b. 75°F c. 37°F The correct answer is: d. all of the above. The answer that is considered correct, however, is: a. 97ºF. This is the critical temperature above which N2O is neither a gas nor a liquid; it is a supercritical fluid. To understand what this means and why the correct answer is “all of the above” you have to know a little about the behavior of liquids and gases. Most people know that water boils at 212ºF. Most people also know that when you’re, for instance, boiling an egg in the mountains, you have to boil it longer to fully cook it. The reason for this has to do with the vapor pressure of water. Every liquid wants to vaporize to some extent. The measure of this tendency is known as the vapor pressure and varies as a function of temperature. When the vapor pressure of a liquid reaches the pressure above it, it boils. Until then, it evaporates until the fraction of vapor in the mixture above it is equal to the ratio of the vapor pressure to the total pressure. At that point it is said to be in equilibrium and no further liquid will evaporate. The vapor pressure of water at 212ºF is 14.696 psi – the atmospheric pressure at sea level. -
Liquid-Vapor Equilibrium in a Binary System
Liquid-Vapor Equilibria in Binary Systems1 Purpose The purpose of this experiment is to study a binary liquid-vapor equilibrium of chloroform and acetone. Measurements of liquid and vapor compositions will be made by refractometry. The data will be treated according to equilibrium thermodynamic considerations, which are developed in the theory section. Theory Consider a liquid-gas equilibrium involving more than one species. By definition, an ideal solution is one in which the vapor pressure of a particular component is proportional to the mole fraction of that component in the liquid phase over the entire range of mole fractions. Note that no distinction is made between solute and solvent. The proportionality constant is the vapor pressure of the pure material. Empirically it has been found that in very dilute solutions the vapor pressure of solvent (major component) is proportional to the mole fraction X of the solvent. The proportionality constant is the vapor pressure, po, of the pure solvent. This rule is called Raoult's law: o (1) psolvent = p solvent Xsolvent for Xsolvent = 1 For a truly ideal solution, this law should apply over the entire range of compositions. However, as Xsolvent decreases, a point will generally be reached where the vapor pressure no longer follows the ideal relationship. Similarly, if we consider the solute in an ideal solution, then Eq.(1) should be valid. Experimentally, it is generally found that for dilute real solutions the following relationship is obeyed: psolute=K Xsolute for Xsolute<< 1 (2) where K is a constant but not equal to the vapor pressure of pure solute. -
Pressure Vs Temperature (Boiling Point)
Boiling Points and Vapor Pressure Background Boiling Points and Vapor Pressure Background: Definitions Vapor Pressure: The equilibrium pressure of a vapor above its liquid; the pressure of the vapor resulting from the evaporation of a liquid above a sample of the liquid in a closed container. Boiling Point: The temperature at which the vapor pressure of a liquid is equal to the atmospheric (or applied) pressure. As the temperature of the liquid increases, the vapor pressure will increase, as seen below: https://www.chem.purdue.edu/gchelp/liquids/vpress.html Vapor pressure is interpreted in terms of molecules of liquid converting to the gaseous phase and escaping into the empty space above the liquid. In order for the molecules to escape, the intermolecular forces (Van der Waals, dipole- dipole, and hydrogen bonding) have to be overcome, which requires energy. This energy can come in the form of heat, aka increase in temperature. Due to this relationship between vapor pressure and temperature, the boiling point of a liquid decreases as the atmospheric pressure decreases since there is more room above the liquid for molecules to escape into at lower pressure. The graph below illustrates this relationship using common solvents and some terpenes: Pressure vs Temperature (boiling point) Ethanol Heptane Isopropyl Alcohol B-myrcene 290.0 B-caryophyllene d-Limonene Linalool Pulegone 270.0 250.0 1,8-cineole (eucalyptol) a-pinene a-terpineol terpineol-4-ol 230.0 p-cymene 210.0 190.0 170.0 150.0 130.0 110.0 90.0 Temperature (˚C) Temperature 70.0 50.0 30.0 10 20 30 40 50 60 70 80 90 100 200 300 400 500 600 760 10.0 -10.0 -30.0 Pressure (torr) 1 Boiling Points and Vapor Pressure Background As a very general rule of thumb, the boiling point of many liquids will drop about 0.5˚C for a 10mmHg decrease in pressure when operating in the region of 760 mmHg (atmospheric pressure). -
Statistical Mechanics I: Exam Review 1 Solution
8.333: Statistical Mechanics I Fall 2007 Test 1 Review Problems The first in-class test will take place on Wednesday 9/26/07 from 2:30 to 4:00 pm. There will be a recitation with test review on Friday 9/21/07. The test is ‘closed book,’ but if you wish you may bring a one-sided sheet of formulas. The test will be composed entirely from a subset of the following problems. Thus if you are familiar and comfortable with these problems, there will be no surprises! ******** You may find the following information helpful: Physical Constants 31 27 Electron mass me 9.1 10− kg Proton mass mp 1.7 10− kg ≈ × 19 ≈ × 34 1 Electron Charge e 1.6 10− C Planck’s const./2π ¯h 1.1 10− Js− ≈ × 8 1 ≈ × 8 2 4 Speed of light c 3.0 10 ms− Stefan’s const. σ 5.7 10− W m− K− ≈ × 23 1 ≈ × 23 1 Boltzmann’s const. k 1.4 10− JK− Avogadro’s number N 6.0 10 mol− B ≈ × 0 ≈ × Conversion Factors 5 2 10 4 1atm 1.0 10 Nm− 1A˚ 10− m 1eV 1.1 10 K ≡ × ≡ ≡ × Thermodynamics dE = T dS+dW¯ For a gas: dW¯ = P dV For a wire: dW¯ = Jdx − Mathematical Formulas √π ∞ n αx n! 1 0 dx x e− = αn+1 2 ! = 2 R 2 2 2 ∞ x √ 2 σ k dx exp ikx 2σ2 = 2πσ exp 2 limN ln N! = N ln N N −∞ − − − →∞ − h i h i R n n ikx ( ik) n ikx ( ik) n e− = ∞ − x ln e− = ∞ − x n=0 n! � � n=1 n! � �c P 2 4 P 3 5 cosh(x) = 1 + x + x + sinh(x) = x + x + x + 2! 4! · · · 3! 5! · · · 2πd/2 Surface area of a unit sphere in d dimensions Sd = (d/2 1)! − 1 1. -
Freezing and Boiling Point Changes
Freezing Point and Boiling Point Changes for Solutions and Solids Lesson Plans and Labs By Ranald Bleakley Physics and Chemistry teacher Weedsport Jnr/Snr High School RET 2 Cornell Center for Materials Research Summer 2005 Freezing Point and Boiling Point Changes for Solutions and Solids Lesson Plans and Labs Summary: Major skills taught: • Predicting changes in freezing and boiling points of water, given type and quantity of solute added. • Solving word problems for changes to boiling points and freezing points of solutions based upon data supplied. • Application of theory to real samples in lab to collect and analyze data. Students will describe the importance to industry of the depression of melting points in solids such as metals and glasses. • Students will describe and discuss the evolution of glass making through the ages and its influence on social evolution. Appropriate grade and level: The following lesson plans and labs are intended for instruction of juniors or seniors enrolled in introductory chemistry and/or physics classes. It is most appropriately taught to students who have a basic understanding of the properties of matter and of solutions. Mathematical calculations are intentionally kept to a minimum in this unit and focus is placed on concepts. The overall intent of the unit is to clarify the relationship between changes to the composition of a mixture and the subsequent changes in the eutectic properties of that mixture. Theme: The lesson plans and labs contained in this unit seek to teach and illustrate the concepts associated with the eutectic of both liquid solutions, and glasses The following people have been of great assistance: Professor Louis Hand Professor of Physics. -
Methods for the Determination of the Normal Boiling Point of a High
Metalworking Fluids & VOC, Today and Tomorrow A Joint Symposium by SCAQMD & ILMA South Coast Air Quality Management District Diamond Bar, CA, USA March 8, 2012 Understanding & Determining the Normal Boiling Point of a High Boiling Liquid Presentation Outline • Relationship of Vapor Pressure to Temperature • Examples of VP/T Curves • Calculation of Airborne Vapor Concentration • Binary Systems • Relative Volatility as a function of Temperature • GC Data and Volatility • Everything Needs a Correlation • Conclusions Vapor Pressure Models (pure vapor over pure liquid) Correlative: • Clapeyron: Log(P) = A/T + B • Antoine: Log(P) = A/(T-C) + B • Riedel: LogP = A/T + B + Clog(T) + DTE Predictive: • ACD Group Additive Methods • Riedel: LogP = A/T + B + Clog(T) + DTE Coefficients defined, Reduced T = T/Tc • Variations: Frost-Kalkwarf-Thodos, etc. Two Parameters: Log(P) = A/T + B Vaporization as an CH OH(l) CH OH(g) activated process 3 3 G = -RTln(K) = -RTln(P) K = [CH3OH(g)]/[CH3OH(l)] G = H - TS [CH3OH(g)] = partial P ln(P) = -G/RT [CH3OH(l)] = 1 (pure liquid) ln(P) = -H/RT+ S/R K = P S/R = B ln(P) = ln(K) H/R = -A Vapor pressure Measurement: Direct versus Distillation • Direct vapor pressure measurement (e.g., isoteniscope) requires pure material while distillation based determination can employ a middle cut with a relatively high purity. Distillation allows for extrapolation and/or interpolation of data to approximate VP. • Direct vapor pressure measurement requires multiple freeze-thaw cycles to remove atmospheric gases while distillation (especially atmospheric distillation) purges atmospheric gases as part of the process. • Direct measurement OK for “volatile materials” (normal BP < 100 oC) but involved for “high boilers” (normal BP > 100 oC). -
Interfaces in Aquatic Ecosystems: Implications for Transport and Impact of I Anthropogenic Compounds Luhbds-«6KE---C)I‘> "Rol°
Interfaces in aquatic ecosystems: Implications for transport and impact of I anthropogenic compounds luhbDS-«6KE---c)I‘> "rol° STER DISTfiStihON OF THIS DOCUMENT iS UNUMITED % In memory of Fetter, victim of human negligence and To my family andfriends Organization Document name LUND UNIVERSITY DOCTORAL DISSERTATION Department of Ecology Date of issue November 19, 1996 Chemical Ecology and Ecotoxicology Ecology Building CODEN: SE- LUNBDS/NBKE-96/1010+136 S-223 62 Lund, Sweden Authors) Sponsoring organization Swedish Environ JOHANNES KNULST mental Research Institute (IVL) Title and subtitle Interfaces in aquatic ecosystems : Implications for transport and impact of anthropogenic compounds Abstract Mechanisms that govern transport, accumulation and toxicity of persistent pollutants at interfaces in aquatic ecosystems were the foci of this thesis . Specific attention was paid to humic substances, their occurrence, composition, and role in exchange processes across interfaces. It was concluded that: The composition of humic substances in aquatic surface microlavers is different from that of the subsurface water and terrestrial humic mat ter. Levels of dissolved organic carbon (DOC)in the aquatic surface micro layer reflect the DOC levels in the subsurface water. While the levels and enrichment of DOC in the microlaver generally show small variations, the levels and enrichment of particulate organic car bon (POC) vary to a great extent. Similarities exist between aquatic surface films, artificial semi-per meable and biological membranes regarding their structure and function ing. Acidification and liming of freshwater ecosystems affect DOC:POC ratio and humic composition of the surface film, thus influencing the parti tioning of pollutants across aquatic interfaces. 21 Properties of lake catchment areas extensively govern DOC:POC ratio both 41 in the surface film and subsurface water. -
Laboratory: Archimedes' Principle
Phy1401: General Physics I Laboratory Page 1 of 4 Laboratory: Archimedes' Principle Introduction: Eureka!! In this lab your goal is to perform some experiments to understand the source of Archimedes’ excitement when he discovered that the buoyant force on an object in a liquid is equal to the weight of the liquid that the object displaces. Archimedes made his discovery without the benefit of Newton's insights. He was arguably the premier scientist of antiquity. Since you have Newton's achievements as part of your intellectual heritage (Phy211) we'll use the concepts of force and equilibrium to measure the buoyant force acting on a (partially or totally) submerged object. Here is the idea behind the experiment. Suppose we hang a small mass from a force sensor, arranged in the configuration shown in the figure below. The bob in the liquid may be partially or totally submerged. H2O Force Sensor mass graduated cylinder According to Archimedes, the upward buoyant force (FB), which the liquid exerts on the object, is equal to the weight of the fluid displaced or: FB = mfluidg = (ρfluidV)g (1). It should be noted, the buoyant force produced by the displacement of fluid in the cylinder will result in a reaction force of equal but opposite magnitude exerted by the bob on the rd liquid (according to Newton’s 3 Law). We will use this action-reaction relation to measure the buoyant “reaction” force with a standard digital scale. While the mass is hanging, the force sensor will measure the tension in the string (FT1), which should be equal to the weight of the suspended mass. -
Floating with Surface Tension from Archimedes to Keller
FLOATING WITH SURFACE TENSION FROM ARCHIMEDES TO KELLER Dominic Vella Mathematical Institute, University of Oxford 1 GFD Newsletter 2006 Faculty of Walsh College JBK @ WHOI Joe was a regular fixture of the Geophysical Fluid Dynamics programme (run at Woods Hole since 1959 – last attended in 2015) usual magic in the Lab. We continue to be endebted to W.H.O.I. Education, who once more provided a perfect atmosphere. Jeanne Fleming, Penny Foster and Janet Fields all contributed importantly to the smooth running of the program. The 2006 GFD Photograph. GFD Photo – 2006 A Sketch of the Summer Ice was the topic under discussion at Walsh Cottage during the 2006 Geophysical Fluid Dynamics Summer Study Program. Professor Grae Worster (University of The dragon enters the ice field. Cambridge) was the principal lecturer, and navigated our path through the fluid dynamics of icy processes in GFD. Towards the end of Grae’s lectures, we also held the 2006 GFD Public Lecture. This was given by Schedule of Principal Lectures Greg Dash of the University of Washington, on matters Week 1: of ice physics and a well-known popularization: “Nine Monday, June 19: Introduction to Ice Ices, Cloud Seeding and a Brother’s Farewell; how Kurt Tuesday, June 20: Diffusion-controlled solidification Vonnegut learned the science for Cat’s Cradle (but con- Wednesday, June 21: Interfacial instability in super- veniently left some out).” We again held the talk at Red- cooled fluid field Auditorium, and relaxed in the evening sunshine Thursday, June 22: Interfacial instability in two- at the reception afterwards. As usual, the principal lec- component melts tures were followed by a variety of seminars on topics icy and otherwise. -
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