16.4 Calculations Involving Colligative Properties 16.4
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Pre Lab: Freezing Point Experiment 1) Define: Colligative Properties. 2
Pre Lab: Freezing Point Experiment 1) Define: Colligative properties. 2) List four Colligative properties. 3) Define: Molal freezing point depression constant, Kf. 4) Does the value of Kf depend on the nature of ( solvent, or solute)?_________ 5) a) Show a freezing point of 6.00 °C on a cooling curve for a pure solvent. temperature time b) If the freezing point of a pure solvent is 6.00 °C, will the solvent which is contaminated with a soluble material have a freezing point (higher than, lower than, or same as) 6.00 °C ? Answer: _________. Explain:_______________________________________________________ c) Show a freezing point on the cooling curve for the above contaminated solvent. temperature time 6) Assume you had used a well calibrated thermometer to measure the freezing point of a solvent, can you tell from the cooling curve if the solvent is contaminated with soluble material?______ How can you tell? a) ____________________ b) _____________________ (Next page) 7) Show the freezing point on a cooling curve for a solvent contaminated with insoluble material. temperature time 8) What is the relationship between ∆T and molar mass of solute? The larger the value of ∆T, the (larger, or smaller) the molar mass of the solute? 9) If some insoluble material contaminated your solution after it had been prepared, how would this effect the measured ∆Tf and the calculated molar mass of solute? Explain: _______________________________________________________ 10) If some soluble material contaminated your solution after it had been prepared, how -
Tutorial 2 FORMULAS, PERCENTAGE COMPOSITION
T-6 Tutorial 2 FORMULAS, PERCENTAGE COMPOSITION, AND THE MOLE FORMULAS: A chemical formula shows the elemental composition of a substance: the chemical symbols show what elements are present and the numerical subscripts show how many atoms of each element there are in a formula unit. Examples: NaCl: one sodium atom, one chlorine atom in a formula unit CaCl2: one calcium atom, two chlorine atoms in a formula unit Mg3N2: three magnesium atoms, two nitrogen atoms in a formula unit The presence of a metal in a chemical formula indicates an ionic compound, which is composed of positive ions (cations) and negative ions (anions). A formula with only nonmetals indicates a + molecular compound (unless it is an ammonium, NH4 , compound). Only ionic compounds are considered in this Tutorial. There are tables of common ions in your lecture text, p 56 (cations) and p 57 (anions). A combined table of these same ions can be found on the inside back cover of the lecture text. A similar list is on the next page; all formulas needed in this and subsequent Tutorial problems can be written with ions from this list. Writing formulas for ionic compounds is very straightforward: TOTAL POSITIVE CHARGES MUST BE THE SAME AS TOTAL NEGATIVE CHARGES. The formula must be neutral. The positive ion is written first in the formula and the name of the compound is the two ion names. EXAMPLE: Write the formula for potassium chloride. The name tells you there are potassium, K+, and chloride, Cl–, ions. Each potassium ion is +1 and each chloride ion is -1: one of each is needed, and the formula for potassium chloride is KCl. -
Page 1 of 6 This Is Henry's Law. It Says That at Equilibrium the Ratio of Dissolved NH3 to the Partial Pressure of NH3 Gas In
CHMY 361 HANDOUT#6 October 28, 2012 HOMEWORK #4 Key Was due Friday, Oct. 26 1. Using only data from Table A5, what is the boiling point of water deep in a mine that is so far below sea level that the atmospheric pressure is 1.17 atm? 0 ΔH vap = +44.02 kJ/mol H20(l) --> H2O(g) Q= PH2O /XH2O = K, at ⎛ P2 ⎞ ⎛ K 2 ⎞ ΔH vap ⎛ 1 1 ⎞ ln⎜ ⎟ = ln⎜ ⎟ − ⎜ − ⎟ equilibrium, i.e., the Vapor Pressure ⎝ P1 ⎠ ⎝ K1 ⎠ R ⎝ T2 T1 ⎠ for the pure liquid. ⎛1.17 ⎞ 44,020 ⎛ 1 1 ⎞ ln⎜ ⎟ = − ⎜ − ⎟ = 1 8.3145 ⎜ T 373 ⎟ ⎝ ⎠ ⎝ 2 ⎠ ⎡1.17⎤ − 8.3145ln 1 ⎢ 1 ⎥ 1 = ⎣ ⎦ + = .002651 T2 44,020 373 T2 = 377 2. From table A5, calculate the Henry’s Law constant (i.e., equilibrium constant) for dissolving of NH3(g) in water at 298 K and 340 K. It should have units of Matm-1;What would it be in atm per mole fraction, as in Table 5.1 at 298 K? o For NH3(g) ----> NH3(aq) ΔG = -26.5 - (-16.45) = -10.05 kJ/mol ΔG0 − [NH (aq)] K = e RT = 0.0173 = 3 This is Henry’s Law. It says that at equilibrium the ratio of dissolved P NH3 NH3 to the partial pressure of NH3 gas in contact with the liquid is a constant = 0.0173 (Henry’s Law Constant). This also says [NH3(aq)] =0.0173PNH3 or -1 PNH3 = 0.0173 [NH3(aq)] = 57.8 atm/M x [NH3(aq)] The latter form is like Table 5.1 except it has NH3 concentration in M instead of XNH3. -
THE SOLUBILITY of GASES in LIQUIDS Introductory Information C
THE SOLUBILITY OF GASES IN LIQUIDS Introductory Information C. L. Young, R. Battino, and H. L. Clever INTRODUCTION The Solubility Data Project aims to make a comprehensive search of the literature for data on the solubility of gases, liquids and solids in liquids. Data of suitable accuracy are compiled into data sheets set out in a uniform format. The data for each system are evaluated and where data of sufficient accuracy are available values are recommended and in some cases a smoothing equation is given to represent the variation of solubility with pressure and/or temperature. A text giving an evaluation and recommended values and the compiled data sheets are published on consecutive pages. The following paper by E. Wilhelm gives a rigorous thermodynamic treatment on the solubility of gases in liquids. DEFINITION OF GAS SOLUBILITY The distinction between vapor-liquid equilibria and the solubility of gases in liquids is arbitrary. It is generally accepted that the equilibrium set up at 300K between a typical gas such as argon and a liquid such as water is gas-liquid solubility whereas the equilibrium set up between hexane and cyclohexane at 350K is an example of vapor-liquid equilibrium. However, the distinction between gas-liquid solubility and vapor-liquid equilibrium is often not so clear. The equilibria set up between methane and propane above the critical temperature of methane and below the criti cal temperature of propane may be classed as vapor-liquid equilibrium or as gas-liquid solubility depending on the particular range of pressure considered and the particular worker concerned. -
Introduction to the Solubility of Liquids in Liquids
INTRODUCTION TO THE SOLUBILITY OF LIQUIDS IN LIQUIDS The Solubility Data Series is made up of volumes of comprehensive and critically evaluated solubility data on chemical systems in clearly defined areas. Data of suitable precision are presented on data sheets in a uniform format, preceded for each system by a critical evaluation if more than one set of data is available. In those systems where data from different sources agree sufficiently, recommended values are pro posed. In other cases, values may be described as "tentative", "doubtful" or "rejected". This volume is primarily concerned with liquid-liquid systems, but related gas-liquid and solid-liquid systems are included when it is logical and convenient to do so. Solubilities at elevated and low 'temperatures and at elevated pressures may be included, as it is considered inappropriate to establish artificial limits on the data presented. For some systems the two components are miscible in all proportions at certain temperatures or pressures, and data on miscibility gap regions and upper and lower critical solution temperatures are included where appropriate and if available. TERMINOLOGY In this volume a mixture (1,2) or a solution (1,2) refers to a single liquid phase containing components 1 and 2, with no distinction being made between solvent and solute. The solubility of a substance 1 is the relative proportion of 1 in a mixture which is saturated with respect to component 1 at a specified temperature and pressure. (The term "saturated" implies the existence of equilibrium with respect to the processes of mass transfer between phases) • QUANTITIES USED AS MEASURES OF SOLUBILITY Mole fraction of component 1, Xl or x(l): ml/Ml nl/~ni = r(m.IM.) '/. -
Lab Colligative Properties Data Sheet Answers
Lab Colligative Properties Data Sheet Answers outspanning:Rem remains hedogging: praising she his disclosed reunionists her tirelessly agrimony and semaphore dustily. Sober too purely? Wiatt demonetising Rhombohedral lissomly. Warren The answers coming up in both involve transformations of salt component of moles of salt flux is where appropriate. Experiment 4 Molar Mass by Freezing Point Depression. The colligative property and answer the colligative properties? Constant is what property set the solvent not the solute. Laboratory Manual An Atoms First Approach illuminate the various Chemistry Laboratory. Wipe the colligative property of solute concentration of in touch the following sensors and answer to its properties multiple choice worksheet. Experiment 2 Graphical Representation of Data and the Use all Excel. Investigation of local church alongside lab partners from one middle or high underneath The engaging. For dilute solutions under ideal conditions A new equal to 1 and. Colligative Properties Study Guide Answers Colligative properties study guide answers. Students will characterize the properties that describe solutions and the saliva of acids and. Do colligative properties lab data sheets, see this conclusion of how they answer. Weber State University. Adding a lab. Stir well in data sheet of colligative effects. Strong electrolytes are a colligative properties of data sheet provided to. If no ally is such a referred solutions lab 33 freezing point answers book that. Chemistry Colligative Properties Answer Key AdvisorNews. Which a property. B Answering about 5-6 questions on eLearning for in particular lab You please be. Colligative Properties Chp14 13 13-Freezing Points of Solutions - leave a copy of store Data company with the TA BEFORE leaving lab 1124 No labs 121. -
Chapter 9: Raoult's Law, Colligative Properties, Osmosis
Winter 2013 Chem 254: Introductory Thermodynamics Chapter 9: Raoult’s Law, Colligative Properties, Osmosis ............................................................ 95 Ideal Solutions ........................................................................................................................... 95 Raoult’s Law .............................................................................................................................. 95 Colligative Properties ................................................................................................................ 97 Osmosis ..................................................................................................................................... 98 Final Review ................................................................................................................................ 101 Chapter 9: Raoult’s Law, Colligative Properties, Osmosis Ideal Solutions Ideal solutions include: - Very dilute solutions (no electrolyte/ions) - Mixtures of similar compounds (benzene + toluene) * Pure substance: Vapour Pressure P at particular T For a mixture in liquid phase * Pi x i P i Raoult’s Law, where xi is the mole fraction in the liquid phase This gives the partial vapour pressure by a volatile substance in a mixture In contrast to mole fraction in the gas phase yi Pi y i P total This gives the partial pressure of the gas xi , yi can have different values. Raoult’s Law Rationalization of Raoult’s Law Pure substance: Rvap AK evap where Rvap = rate of vaporization, -
Chapter 15: Solutions
452-487_Ch15-866418 5/10/06 10:51 AM Page 452 CHAPTER 15 Solutions Chemistry 6.b, 6.c, 6.d, 6.e, 7.b I&E 1.a, 1.b, 1.c, 1.d, 1.j, 1.m What You’ll Learn ▲ You will describe and cate- gorize solutions. ▲ You will calculate concen- trations of solutions. ▲ You will analyze the colliga- tive properties of solutions. ▲ You will compare and con- trast heterogeneous mixtures. Why It’s Important The air you breathe, the fluids in your body, and some of the foods you ingest are solu- tions. Because solutions are so common, learning about their behavior is fundamental to understanding chemistry. Visit the Chemistry Web site at chemistrymc.com to find links about solutions. Though it isn’t apparent, there are at least three different solu- tions in this photo; the air, the lake in the foreground, and the steel used in the construction of the buildings are all solutions. 452 Chapter 15 452-487_Ch15-866418 5/10/06 10:52 AM Page 453 DISCOVERY LAB Solution Formation Chemistry 6.b, 7.b I&E 1.d he intermolecular forces among dissolving particles and the Tattractive forces between solute and solvent particles result in an overall energy change. Can this change be observed? Safety Precautions Dispose of solutions by flushing them down a drain with excess water. Procedure 1. Measure 10 g of ammonium chloride (NH4Cl) and place it in a Materials 100-mL beaker. balance 2. Add 30 mL of water to the NH4Cl, stirring with your stirring rod. -
2•Stoichiometry: Chemical Arithmetic Formula Conventions (1 Of
Superscripts used to show the charges on ions Mg2+ the 2 means a 2+ charge (lost 2 electrons) Subscripts 2•Stoichiometry: Chemical Arithmetic used to show numbers of atoms in a formula unit Formula Conventions H2SO4 two H’s, one S, and 4 O’s (1 of 24) Coefficients used to show the number of formula units 2Br– the 2 means two individual bromide ions Hydrates CuSO4 • 5 H2O some compounds have water molecules included stoichiometry study of the quantitative relationships in chemical formulas and equations. atomic mass weighted average mass of an atom, found on the periodic table 2•Stoichiometry: Chemical Arithmetic formula mass sum of the atomic masses of the Stoichiometry Terms atoms in a formula molecular mass sum of the atomic masses of the (2 of 24) atoms in a molecular formula gram molecular mass molecular mass written in grams molar mass same as gram molecular mass empirical formula formula reduced to lowest terms Formula or molecular mass is found by simply summing the atomic masses (on the periodic table) of each atom in a formula. H2SO4 2•Stoichiometry: Chemical Arithmetic 1.01 + 1.01 + 32.06 + 16.0 + 16.0 + 16.0 + 16.0 = 98.08 u Calculating Formula Mass 2(1.01) + 32.06 + 4(16.0) = 98.06 u or 98.06 g/mole (3 of 24) Generally, round off your answers to the hundredths or tenths place. Don’t round off too much (98.06 g/mol or 98.1 g/mol is OK, but don’t round off to 98 g/mol) Units Use u or amu if you are referring to one atom or molecule A mole (abbreviated mol) is a certain number of things. -
Solute Concentration: Molality
5/25/2012 Colligative Properties of Solutions . Colligative Properties: • Solution properties that depend on concentration of solute particles, not the identity of particles. Previous example: vapor pressure lowering. Consequences: change in b.p. and f.p. of solution. © 2012 by W. W. Norton & Company Solute Concentration: Molality . Changes in boiling point/freezing point of solutions depends on molality: moles of solute m kg of solvent • Preferred concentration unit for properties involving temperature changes because it is independent of temperature. © 2012 by W. W. Norton & Company 1 5/25/2012 Calculating Molality Starting with: a) Mass of solute and solvent. b) Mass of solute/ volume of solvent. c) Volume of solution. © 2012 by W. W. Norton & Company Sample Exercise 11.8 How many grams of Na2SO4 should be added to 275 mL of water to prepare a 0.750 m solution of Na2SO4? Assume the density of water is 1.000 g/mL. © 2012 by W. W. Norton & Company 2 5/25/2012 Boiling-Point Elevation and Freezing-Point Depression . Boiling Point Elevation (ΔTb): • ΔTb = Kb∙m • Kb = boiling point elevation constant of solvent; m = molality. Freezing Point Depression (ΔTf): • ΔTf = Kf∙m • Kf = freezing-point depression constant; m = molality. © 2012 by W. W. Norton & Company Sample Exercise 11.9 What is the boiling point of seawater if the concentration of ions in seawater is 1.15 m? © 2012 by W. W. Norton & Company 3 5/25/2012 Sample Exercise 11.10 What is the freezing point of radiator fluid prepared by mixing 1.00 L of ethylene glycol (HOCH2CH2OH, density 1.114 g/mL) with 1.00 L of water (density 1.000 g/mL)? The freezing-point-depression constant of water, Kf, is 1.86°C/m. -
Δtb = M × Kb, Δtf = M × Kf
8.1HW Colligative Properties.doc Colligative Properties of Solvents Use the Equations given in your notes to solve the Colligative Property Questions. ΔTb = m × Kb, ΔTf = m × Kf Freezing Boiling K K Solvent Formula Point f b Point (°C) (°C/m) (°C/m) (°C) Water H2O 0.000 100.000 1.858 0.521 Acetic acid HC2H3O2 16.60 118.5 3.59 3.08 Benzene C6H6 5.455 80.2 5.065 2.61 Camphor C10H16O 179.5 ... 40 ... Carbon disulfide CS2 ... 46.3 ... 2.40 Cyclohexane C6H12 6.55 80.74 20.0 2.79 Ethanol C2H5OH ... 78.3 ... 1.07 1. Which solvent’s freezing point is depressed the most by the addition of a solute? This is determined by the Freezing Point Depression constant, Kf. The substance with the highest value for Kf will be affected the most. This would be Camphor with a constant of 40. 2. Which solvent’s freezing point is depressed the least by the addition of a solute? By the same logic as above, the substance with the lowest value for Kf will be affected the least. This is water. Certainly the case could be made that Carbon disulfide and Ethanol are affected the least as they do not have a constant. 3. Which solvent’s boiling point is elevated the least by the addition of a solute? Water 4. Which solvent’s boiling point is elevated the most by the addition of a solute? Acetic Acid 5. How does Kf relate to Kb? Kf > Kb (fill in the blank) The freezing point constant is always greater. -
Lecture 3. the Basic Properties of the Natural Atmosphere 1. Composition
Lecture 3. The basic properties of the natural atmosphere Objectives: 1. Composition of air. 2. Pressure. 3. Temperature. 4. Density. 5. Concentration. Mole. Mixing ratio. 6. Gas laws. 7. Dry air and moist air. Readings: Turco: p.11-27, 38-43, 366-367, 490-492; Brimblecombe: p. 1-5 1. Composition of air. The word atmosphere derives from the Greek atmo (vapor) and spherios (sphere). The Earth’s atmosphere is a mixture of gases that we call air. Air usually contains a number of small particles (atmospheric aerosols), clouds of condensed water, and ice cloud. NOTE : The atmosphere is a thin veil of gases; if our planet were the size of an apple, its atmosphere would be thick as the apple peel. Some 80% of the mass of the atmosphere is within 10 km of the surface of the Earth, which has a diameter of about 12,742 km. The Earth’s atmosphere as a mixture of gases is characterized by pressure, temperature, and density which vary with altitude (will be discussed in Lecture 4). The atmosphere below about 100 km is called Homosphere. This part of the atmosphere consists of uniform mixtures of gases as illustrated in Table 3.1. 1 Table 3.1. The composition of air. Gases Fraction of air Constant gases Nitrogen, N2 78.08% Oxygen, O2 20.95% Argon, Ar 0.93% Neon, Ne 0.0018% Helium, He 0.0005% Krypton, Kr 0.00011% Xenon, Xe 0.000009% Variable gases Water vapor, H2O 4.0% (maximum, in the tropics) 0.00001% (minimum, at the South Pole) Carbon dioxide, CO2 0.0365% (increasing ~0.4% per year) Methane, CH4 ~0.00018% (increases due to agriculture) Hydrogen, H2 ~0.00006% Nitrous oxide, N2O ~0.00003% Carbon monoxide, CO ~0.000009% Ozone, O3 ~0.000001% - 0.0004% Fluorocarbon 12, CF2Cl2 ~0.00000005% Other gases 1% Oxygen 21% Nitrogen 78% 2 • Some gases in Table 3.1 are called constant gases because the ratio of the number of molecules for each gas and the total number of molecules of air do not change substantially from time to time or place to place.