DOCSLIB.ORG

19.3 Equilibria of Slightly Soluble Ionic Compounds K

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
19.3 Equilibria of Slightly Soluble Ionic Compounds K 19.3 Equilibria of Slightly Soluble Ionic Example: Write the solubility-product Compounds expression for Al(OH)3. – Slightly soluble ionic solids reach equilibrium with their → The subscripts in the formula become powers in saturated solutions at very low concentrations of the the solubility-product expression dissolved solute 3+ - 3 –The dissolved portion of the ionic solid is assumed to be ⇒ Ksp = [Al ][OH ] completely dissociated to ions (not always the case) ¾ Sulfides are slightly different since S2- acts as a - The Solubility-Product Constant (Ksp) strong base in water and converts entirely to OH ¾For an ionic solid, MpAq, in equilibrium with its Example: Ag2S saturated solution, the equilibrium constant of the Ag S(s) ↔ 2Ag+ + S2- dissolution process is called solubility-product 2 S2- + H O(l) → HS- + OH- M A (s) ↔ pMm+ + qAn- 2 p q + - - + → Ag2S(s) + H2O(l) ↔ 2Ag + HS + OH m+ p n- q + 2 - - K sp = [M ] [A ] ⇒ Ksp = [Ag ] [HS ][OH ] • Ksp is a measure of the extent to which the Example: The solubility of Pb(IO3)2 is 0.022 g/L solubility equilibrium proceeds to the right at 25°C. Calculate Ksp of Pb(IO3)2. → Convert the solubility to molar solubility, s ↑Ksp ⇔↑Solubility – K depends on temperature g Pb(IO ) 1 mol Pb(IO ) -5 mol sp s = 0.022 3 2 × 3 2 = 3.9×10 L 557 g Pb(IO3 )2 L Calculations Involving Ksp → Express K through the molar solubility, s • Molar solubility (s) – the molarity of the sp 2+ - saturated solution (mol/L) Pb(IO3)2(s) ↔ Pb + 2IO3 2+ – The solubility is often expressed in g/L or 1 mol Pb(IO3)2 → 1 mol Pb - grams/100 mL of solution → can be easily 1 mol Pb(IO3)2 → 2 mol IO3 converted to mol/L 2+ - ⇒ [Pb ] = s and [IO3 ] = 2s – Ksp can be experimentally determined by 2+ - 2 2 3 measuring the molar solubility, s ⇒ Ksp = [Pb ][IO3 ] = s(2s) = 4s -5 3 -13 – s can be calculated if Ksp is known ⇒ Ksp = 4×(3.9×10 ) = 2.5×10 1 -5 Example: The Ksp of Ag2SO4 is 1.4×10 at ¾Ksp can be used as a guide in comparing molar solubilities of different ionic compounds (works 24°C. Calculate the molar solubility of Ag2SO4. → Express K through the molar solubility, s only if the compounds have the same number of ions sp in the formula) + 2- Ag2SO4(s) ↔ 2Ag + SO4 ↑Ksp ⇔↑s + 2- ⇒ [Ag ] = 2s and [SO4 ] = s + 2 2- 2 3 ⇒ Ksp = [Ag ] [SO4 ]= (2s) s = 4s 3 1/3 ⇒ s = Ksp/4 ⇒ s = (Ksp/4) ⇒ s = (1.4×10-5/4)1/3 = 1.5×10-2 M + 2- Note: The problem Ag2SO4(s) ↔ 2Ag + SO4 can be solved using an i excess 0 0 ice table: c -s +2s +s 2 3 ⇒ Ksp = (2s) s = 4s e excess 2s s The Common Ion Effect Example: At a given temperature, Ksp of AgBr is ¾ For a slightly soluble ionic solid, MA 7.7×10-13. Estimate the solubility of AgBr in: n+ n- n+ n- a) Pure H O b) 0.10 M CaBr solution MA(s) ↔ M + A Ksp = [M ][A ] 2 2 –If Mn+ is added by means of the soluble salt a) In pure H2O (MB), the equilibrium shifts to the left toward → Express Ksp through the molar solubility, s formation of more MA(s) AgBr(s) ↔ Ag+ + Br- n+ – MA and MB have a common ion (M ) i excess 0 0 – Similarly, if An- is added to the solution, the c -s +s +s equilibrium also shifts to the left toward e excess s s formation of more MA(s) ⇒ [Ag+] = s and [Br-] = s ⇒The molar solubility decreases in the presence ⇒ K = [Ag+][Br-]= s2 of common ions sp 1/2 -13 1/2 -7 ⇒ s = (Ksp) = (7.7×10 ) = 8.8×10 M 2 b) In 0.10 M CaBr2 solution The Effect of pH on Solubility - - 0.10 M CaBr2 → 0.20 M Br (Br is the common ion) ¾ The solubility of some ionic solids in water is → Express Ksp through the molar solubility, s greatly affected by the pH + - AgBr(s) ↔ Ag + Br – Metal hydroxides (Fe(OH)3, Mg(OH)2, …) – the - + i excess 0 0.20 anion (OH ) reacts with added H3O c -s +s +s ⇒The solubility can be improved by adding acids e excess s 0.20 + s Example: Mg(OH)2 ⇒ K = [Ag+][Br-]= s(0.20 + s) 2+ - sp Mg(OH)2(s) ↔ Mg + 2OH Assume s << 0.20 K = s(0.20) + → ⇒ sp → If acid (H3O ) is added: -13 -12 + - + - ⇒ s = Ksp/0.20 = 7.7×10 /0.20 = 3.8×10 M →H3O consumes OH (H3O + OH → 2H2O) → Check assumption → OK →The equilibrium shifts to the right and the solubility increases ⇒ The solubility is much lower in 0.1 M CaBr2 – Salts of weak acids (CaCO3, BaSO3, PbF2, ZnS, Predicting Precipitation – Q versus K …) – the anion of the salt is a weak base which sp sp + ¾ The reaction quotient of the dissolution reacts with added H3O ⇒The solubility can be improved by adding acids process (Qsp) is defined in the same way as K and at equilibrium Q = K Example: BaSO (a salt of H SO ) sp sp sp 3 2 3 ¾ To predict precipitation, compare Q to K 2+ 2- sp sp BaSO3(s) ↔ Ba + SO3 → If Q > K , precipitation occurs + sp sp → If acid (H3O ) is added: → If Qsp < Ksp, dissolution occurs (no precipitation) 2- + - SO3 + H3O → HSO3 + H2O(l) → If Qsp = Ksp, no change occurs →H O+ consumes SO 2- 3 3 Example: Does a precipitate form after →The equilibrium shifts to the right and the -4 solubility increases mixing of 200. mL 1.0×10 M AgNO3 with -6 Example: CaCO (s) ↔ Ca2+ + CO 2- 900. mL 1.0×10 KCl? 3 3 -10 2- + (K = 1.8×10 for AgCl) CO3 + 2H3O → H2CO3 +H2O(l) → CO2(g) + 2H2O(l) sp 3 (aq) (aq) (s) (aq) → AgNO3 + KCl → AgCl + KNO3 → Calculate Qsp: + - + - -5 -7 → Net ionic equation: Ag + Cl → AgCl(s) Qsp = [Ag ][Cl ] = (1.8×10 )×(8.2×10 ) + - -11 → Reverse: AgCl(s) → Ag + Cl Qsp =1.5×10 -10 + - -10 Ksp = 1.8×10 Ksp = [Ag ][Cl ]= 1.8×10 Vtot = 0.200 + 0.900 = 1.100 L ⇒ Qsp < Ksp → Initial concentrations after mixing: ⇒ No precipitation occurs -4 mol 1.0×10 × 0.200 L mol [Ag+ ] = L = 1.8×10-5 1.100 L L -6 mol 1.0×10 × 0.900 L mol [Cl- ] = L = 8.2×10-7 1.100 L L 4.
Load more

Recommended publications
  • Solubility Equilibria and the Solubility Product Constant
    Solubility Equilibria and the Solubility Product Constant Chapter 7.6 Solubility Equilibria of Ionic Compounds • Solubility is the quantity of solute that dissolves in a given quantity of solvent at a particular temperature • A solubility equilibrium is a dynamic equilibrium between a solute and a solvent in a saturated solution in a closed system The Solubility Product Constant (Ksp) • The Solubility Product Constant (Ksp) is the value obtained from the equilibrium law applied to a saturated solution In any solubility Remember: solids are not equilibrium, the included in the equilibrium law reactant is a solid because their concentrations do not change -17 The Ksp of AgI(s) is 8.3x10 at 25⁰C Ksp values for a number of different solids are found in your textbook on page 725 Practice • Write the solubility product constant equation for each of the following: 2+ - a) MgF2 (s) Mg (aq) + 2F (aq) + 2- b) Ag2CO3 (s) 2Ag (aq) + CO3 (aq) 2+ 3- c) Ca3(PO4)2 (s) 3Ca (aq) + 2PO4 (aq) Solubility and the Solubility Product Constant • Solubility can be expressed in two ways: 1) Molar Solubility is the number of moles of solute dissolved in a given volume of a saturated solution 2) Mass per Volume Solubility is the number of grams of solute dissolved in a given volume of a saturated solution • It is possible to convert between either solubility and Ksp Example 1 -12 • The molar solubility of Pb3(PO4)2 is 6.2 x 10 mol/L. Calculate the Ksp value. Example 2 • What is the solubility of silver chloride in g/L if -10 Ksp = 1.6 x 10 ? Predicting Precipitation
    [Show full text]
  • Changes in Total Dissolved Solids Concentration During Infiltration Through Soils (Rain, Fresh Groundwater and Treated Wastewater)
    Journal of Environmental Protection, 2017, 8, 34-41 http://www.scirp.org/journal/jep ISSN Online: 2152-2219 ISSN Print: 2152-2197 Changes in Total Dissolved Solids Concentration during Infiltration through Soils (Rain, Fresh Groundwater and Treated Wastewater) Alsharifa Hind Mohammad1*, Ghaidaa Abdullat2, Khitam Alzughoul3 1Water, Energy and Environment Center, The University of Jordan, Amman, Jordan 2Freelancers, Amman, Jordan 3Environmental and Applied Geology, School of Science, The University of Jordan, Amman, Jordan How to cite this paper: Mohammad, A.H., Abstract Abdullat, G. and Alzughoul, K. (2017) Changes in Total Dissolved Solids Concentration dur- Water quality deterioration took place during infiltration process. Quality of ing Infiltration through Soils (Rain, Fresh the source water, climate conditions and amounts of added water are the ma- Groundwater and Treated Wastewater). Jour- jor role players of the differentiation measures. Treated wastewater, rainwater nal of Environmental Protection, 8, 34-41. http://dx.doi.org/10.4236/jep.2017.81004 and fresh groundwater were described within this study. It was found that the rainwater has an aggressive behavior with a high ability to dissolve soil Received: October 30, 2016 salts. The amounts of Total Dissolved Solids (TDS) increase with infiltration Accepted: January 13, 2017 Published: January 16, 2017 process. Electrical conductivity (EC) increased by 600%. Plotting the fresh groundwater to the same conditions and experiment reflects the ability of this Copyright © 2017 by authors and water to dissolve soil salts and increases the TDS by increasing the EC by a Scientific Research Publishing Inc. percentage of around 200%; while applying lower quality of water, the per- This work is licensed under the Creative Commons Attribution International centage of the EC of the treated wastewater increases to about 230% for the License (CC BY 4.0).
    [Show full text]
  • Experimental Determination of Henry's Law Constants of Difluoromethane
    Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-58, 2017 Manuscript under review for journal Atmos. Chem. Phys. Discussion started: 8 February 2017 c Author(s) 2017. CC-BY 3.0 License. Experimental determination of Henry’s law constants of difluoromethane (HFC-32) and the salting-out effects in aqueous salt solutions relevant to seawater Shuzo Kutsuna 5 National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, 305-8569, Japan Correspondence to: S. Kutsuna ([email protected]) S −1 Abstract. Gas-to-water equilibrium coefficients, Keq (in M atm ) of difluoromethane (CH2F2), a hydrofluorocarbon refrigerant (HFC-32), in aqueous salt solutions relevant to seawater were determined over a temperature (T) range from 276 to 313 K and a salinity (S) range up to 51 ‰ by means of an inert-gas stripping method. From the van’t Hoff equation, the S −1 10 Keq value in water, which corresponds to the Henry's law constant (KH), at 298 K was determined to be 0.064 M atm . The S S salinity dependence of Keq (the salting-out effect), ln(KH/Keq ), did not obey the Sechenov equation but was represented by 0.5 S S an equation involving S and S . Overall, the Keq (T) value was expressed by ln(Keq (T)) = −49.7122 + 77.7018×(100/T) + 19.1379×ln(T/100) + [−0.2261 + 0.5176×(T/100)] × S 0.5 + [0.0362 − 0.1046×(T/100)] × S. By using this equation in a lower tropospheric semi-hemisphere (30° S−90° S) of the Advanced Global Atmospheric Gases Experiment (AGAGE) 12-box 15 model, we estimated that 1 to 5 % of the atmospheric burden of CH2F2 resided in the ocean mixed layer and that this percentage was at least 5 % in the winter; dissolution of CH2F2 in the ocean may partially influence estimates of CH2F2 emissions from long-term observational data of atmospheric CH2F2 concentrations.
    [Show full text]
  • Equilibria of Other Reaction Classes 839
    Chapter 15 | Equilibria of Other Reaction Classes 839 Chapter 15 Equilibria of Other Reaction Classes Figure 15.1 The mineral fluorite (CaF2) is deposited through a precipitation process. Note that pure fluorite is colorless, and that the color in this sample is due to the presence of other metals in the crystal. Chapter Outline 15.1 Precipitation and Dissolution 15.2 Lewis Acids and Bases 15.3 Multiple Equilibria Introduction In Figure 15.1, we see a close-up image of the mineral fluorite, which is commonly used as a semiprecious stone in many types of jewelry because of its striking appearance. These solid deposits of fluorite are formed through a process called hydrothermal precipitation. In this process, the fluorite remains dissolved in solution, usually in hot water heated by volcanic activity deep below the earth, until conditions arise that allow the mineral to come out of solution and form a deposit. These deposit-forming conditions can include a change in temperature of the solution, availability of new locations to form a deposit such as a rock crevice, contact between the solution and a reactive substance such as certain types of rock, or a combination of any of these factors. We previously learned about aqueous solutions and their importance, as well as about solubility rules. While this gives us a picture of solubility, that picture is not complete if we look at the rules alone. Solubility equilibrium, which we will explore in this chapter, is a more complex topic that allows us to determine the extent to which a slightly soluble ionic solid will dissolve, and the conditions under which precipitation (such as the fluorite deposit in Figure 15.1) will occur.
    [Show full text]
  • Calculation of the Water-Octanol Partition Coefficient of Cholesterol for SPC, TIP3P, and TIP4P Water
    Calculation of the water-octanol partition coefficient of cholesterol for SPC, TIP3P, and TIP4P water Cite as: J. Chem. Phys. 149, 224501 (2018); https://doi.org/10.1063/1.5054056 Submitted: 29 August 2018 . Accepted: 13 November 2018 . Published Online: 11 December 2018 Jorge R. Espinosa, Charlie R. Wand, Carlos Vega , Eduardo Sanz, and Daan Frenkel COLLECTIONS This paper was selected as an Editor’s Pick ARTICLES YOU MAY BE INTERESTED IN Common microscopic structural origin for water’s thermodynamic and dynamic anomalies The Journal of Chemical Physics 149, 224502 (2018); https://doi.org/10.1063/1.5055908 Improved general-purpose five-point model for water: TIP5P/2018 The Journal of Chemical Physics 149, 224507 (2018); https://doi.org/10.1063/1.5070137 Comparison of simple potential functions for simulating liquid water The Journal of Chemical Physics 79, 926 (1983); https://doi.org/10.1063/1.445869 J. Chem. Phys. 149, 224501 (2018); https://doi.org/10.1063/1.5054056 149, 224501 © 2018 Author(s). THE JOURNAL OF CHEMICAL PHYSICS 149, 224501 (2018) Calculation of the water-octanol partition coefficient of cholesterol for SPC, TIP3P, and TIP4P water Jorge R. Espinosa,1 Charlie R. Wand,2,3 Carlos Vega,1 Eduardo Sanz,1 and Daan Frenkel2 1Departamento de Quimica Fisica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid, Spain 2Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom 3School of Chemical Engineering and Analytical Science, University of Manchester, Manchester M13 9PL, United Kingdom (Received 29 August 2018; accepted 13 November 2018; published online 11 December 2018) We present a numerical study of the relative solubility of cholesterol in octanol and water.
    [Show full text]
  • This Article Appeared in a Journal Published by Elsevier. the Attached
    This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Author's personal copy Chemosphere 86 (2012) 634–640 Contents lists available at SciVerse ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere Linear and non-linear relationships between soil sorption and hydrophobicity: Model, validation and influencing factors ⇑ Yang Wen, Li M. Su, Wei C. Qin, Ling Fu, Jia He, Yuan H. Zhao Key Laboratory for Wetland Ecology and Vegetation Restoration of National Environmental Protection, Department of Environmental Sciences, Northeast Normal University, Changchun, Jilin 130024, PR China article info abstract Article history: The hydrophobic parameter represented by the octanol/water partition coefficient (logP) is commonly Received 5 July 2011 used to predict the soil sorption coefficient (Koc). However, a simple non-linear relationship between log- Received in revised form 1 November 2011 Koc and logP has not been reported in the literature. In the present paper, soil sorption data for 701 com- Accepted 1 November 2011 pounds was investigated. The results show that logK is linearly related to logP for compounds with logP Available online 9 December 2011 oc in the range of 0.5–7.5 and non-linearly related to logP for the compounds in a wide range of logP.
    [Show full text]
  • Lecture 20: Solubility and Acid-Base Equilibrium
    5.111 Lecture Summary #20 Monday October 27, 2014 th Reading for Today: Sections 9.8 - 9.13 (8.8-8.13 same in 4 ed.) on solubility; Sections 11.1 th – 11.2, 11.4-11.6 (10.1-10.2, 10.4-10.6 in 4 ed.) on acids and bases. th Reading for Lecture #21: Sections 11.7-11.9, 11.11-11.13 (10.7 -10.9, 10.11 – 10.13 in 4 ed). Topics: I. Solutions and Solubility II. Classification of Acids and Bases I. SOLUTIONS AND SOLUBILITY So far, we’ve been discussing pure compounds. However, most substances are . Solutions are homogeneous mixtures. Solvent: the substance that does the dissolving (i.e. water) Solute: any dissolved substance in a solution MOLAR SOLUBILITY Ionic solids. Consider NaCl dissolving in water. Polar water molecules ions at the surface of the salt’s crystal lattice, prying some of the Na+ and Cl- ions away. Stirring can the process by bringing more free water molecules to the surface of the solid, and taking more hydrated ions away. Solubility equilibrium: NaCl (s) Na+ (aq) + Cl- (aq) + - Ksp = [Na ][Cl ] where sp stands for “solubility product” is a measure of the dissolution of an ionic solid in water. Note NaCl does not appear in the expression since it is a solid. Organic solids. Consider glucose dissolving in water. Water molecules form hydrogen bonds to the glucose molecules near the surface of a glucose crystal. Some glucose molecules are pulled away by the surrounding water (are solubilized), other molecules are not.
    [Show full text]
  • A New Method of Constructing Drug-Polymer Temperature-Composition Phase Diagram Relevant to the Hot-Melt Extrusion Platform
    A new method of constructing drug-polymer temperature-composition phase diagram relevant to the hot-melt extrusion platform Tian, Y., Jones, D., Donnelly, C., Brannigan, T., Li, S., & Andrews, G. (2017). A new method of constructing drug-polymer temperature-composition phase diagram relevant to the hot-melt extrusion platform. Molecular Pharmaceutics, 1-39. https://doi.org/10.1021/acs.molpharmaceut.7b00445 Published in: Molecular Pharmaceutics Document Version: Peer reviewed version Queen's University Belfast - Research Portal: Link to publication record in Queen's University Belfast Research Portal Publisher rights Copyright © 2017 American Chemical Society. This work is made available online in accordance with the publisher’s policies. Please refer to any applicable terms of use of the publisher. General rights Copyright for the publications made accessible via the Queen's University Belfast Research Portal is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. Take down policy The Research Portal is Queen's institutional repository that provides access to Queen's research output. Every effort has been made to ensure that content in the Research Portal does not infringe any person's rights, or applicable UK laws. If you discover content in the Research Portal that you believe breaches copyright or violates any law, please contact [email protected]. Download date:27. Sep. 2021 Determining Risk of Barrett’s Esophagus and Esophageal Adenocarcinoma Based on Epidemiologic Factors and Genetic VariantsA new method of constructing drug-polymer temperature-composition phase diagram relevant to the hot- melt extrusion platform Yiwei Tian, David S.
    [Show full text]
  • Development of Predictive Tools for Amorphous Solid Dosage Forms
    __________________________________________________________ Development of predictive tools for amorphous solid dosage forms Dissertation zur Erlangung des Grades „Doktor der Naturwissenschaften” im Promotionsfach Pharmazie am Fachbereich Chemie, Pharmazie und Geowissenschaften Institut für Pharmazie und Biochemie Abteilung Biopharmazie und Pharmazeutische Technologie der Johannes Gutenberg Universität Mainz Matthias Manne Knopp geboren in Glostrup, Dänemark Mainz, 2016 D77 – Mainzer Dissertation Dekan: Univ.-Prof. Dr. Dirk Schneider 1. Berichterstatter: 2. Berichterstatter: Tag der mündlichen Prüfung: 4. November 2016 “The value of an education is not learning facts, but training the mind to think something that cannot be learned from textbooks” – Albert Einstein Acknowledgements i Abbreviations list ANOVA Analysis of variance AUC Area under the curve BCS Biopharmaceutics classification system BDDCS Biopharmaceutics drug disposition classification system Cmax Maximum concentration CAP Chloramphenicol CCX Celecoxib COX Cyclooxygenase Cp Heat capacity DCS Developability classification system DSC Differential scanning calorimetry EDTA Ethylenediaminetetraacetic acid FaSSIF Fasted state simulated intestinal fluid FeSSIF Fed state simulated intestinal fluid FDA Food and Drug Administration (USA) FDP Felodipine FTIR Fourier transform infrared Hm Melting enthalpy (enthalpy of fusion) HPC Hydroxypropyl cellulose HPLC High-performance liquid chromatography HPMC Hydroxypropyl methylcellulose HPMCAS Hydroxypropyl methylcellulose acetate succinate
    [Show full text]
  • Thermodynamics of Solubility: Graphical Determination of ΔH and ΔS
    Thermodynamics of Solubility: Graphical Determination of ΔH and ΔS Objectives: To determine the thermodynamic values of ΔH and ΔS for the dissolution of a salt in aqueous solution Materials: Potassium chloride (KCl): distilled water Equipment: 25 x 250-mm test tube with 2-hole rubber stopper; thermometer; glass or wire stirring rod; iron rings and ring stand assembly (see Figure 1); ceramic-centered gauze heating pad; 400-mL beaker; Bunsen burner Safety: Some inorganic salts/solutions are irritants. All samples and solutions should be handled carefully. Hot glassware should be handled with care. Eye goggles and appropriate lab attire should be worn at all times in the lab. Waste Salt solutions should be placed in the inorganic waste container provided in the disposal: fume hood. PRESS INTRODUCTION The amount of solute that will dissolve in water depends on many factors, including temperature and the nature of the solute and solvent (i.e., molecular vs. ionic, polar vs. non-polar). Salts, such as table salt (sodium chloride), are ionic compounds consisting of cations and anions; ionic compounds are usually soluble in water, but the extent of solubility will vary from one salt to another. The dissolution process can be expressed as an equilibrium, in which the dissolved ions are in equilibrium with undissolvedCOPYRIGHT solid in a saturated solution . For example, the dissolution of a sparingly soluble salt, CaF2 can be represented as 2+ - 2+ - 2 CaF2(s) ↔ Ca (aq) + 2F (aq) Ksp = [Ca ][F ] where the bidirectional arrow indicates an equilibrium between products and reactants, and Ksp is the equilibrium constant for the solubility equilibrium.
    [Show full text]
  • Phase Diagrams of Polymer-Dispersed Liquid Crystal Systems of Itraconazole – Component Immiscibility Induced by Molecular Anisotropy
    Phase diagrams of polymer-dispersed liquid crystal systems of itraconazole – component immiscibility induced by molecular anisotropy Agnieszka Kozyra1, Naila A. Mugheirbi1,2, Krzysztof J. Paluch3, Grzegorz Garbacz4, Lidia Tajber1* 1School of Pharmacy and Pharmaceutical Sciences, Trinity College Dublin, Dublin 2, Ireland. 2Drug Product Science and Technology, Bristol-Myers Squibb, East Brunswick, New Jersey, 08901, USA. 3School of Pharmacy and Medical Sciences, Faculty of Life Sciences, Centre for Pharmaceutical Engineering Science, University of Bradford, Richmond Road, Bradford, W. Yorks., BD7 1DP, UK. 4Physiolution GmbH, Walther-Rathenau Strasse 49a, 17489 Greifswald, Germany. *To whom correspondence should be addressed: [email protected] Phone: 00353 1 896 2787 Keywords: itraconazole, nematic, smectic, phase diagram, miscibility, Flory-Huggins theory, Maier-Saupe-McMillan theory 1 Abstract Liquid crystalline (LC) materials and their non-medical applications have been known for decades, especially in the production of displays, however the pharmaceutical implications of the LC state are inadequately appreciated and experimental data misunderstood leading to possible errors, especially in relation to physical stability of medicines. The aim of this work was to study LC phases of itraconazole (ITZ), an azole antifungal active molecule, and, for the first time, to generate full thermodynamic phase diagrams for ITZ/polymer systems taking into account isotropic and anisotropic phases that this drug can form. It was found that supercooled ITZ does not form an amorphous, but a vitrified smectic (vSm) phase with a glass transition temperature of 59.35 °C (determined using a 10°C/min heating rate), as evident from X-ray diffraction and thermomicroscopic (PLM) experiments. Two endothermic LC events with the onset temperature values for a smectic to nematic transition of 73.2±0.4 °C and a nematic to isotropic transformation at 90.4±0.35 °C and enthalpies of transition of 416±34 J/mol and 842±10 J/mol, respectively, were recorded.
    [Show full text]
  • Determination of Ksp, AG˚, AH˚ and AS˚ for Ca(OH)2
    CH 223 Spring 2022: “Determination of Ksp, ΔG˚, ΔH˚ and ΔS˚ for Ca(OH)2” (in class) Lab: Instructions Note: This is the lab for section 01 and H1 of CH 223 only. • If you are taking section W1 of CH 223, please use this link: http://mhchem.org/q/7b.htm Step One: Print this lab! You will need a printed (hard copy) version of pages I-7-2 through I-7-12 to complete this lab. If you do not turn in a printed copy of the lab, there will be a 2-point deduction. Step Two: Bring the printed copy of the lab with you on Wednesday, May 18. During lab in room AC 2507, you will use these sheets (with the valuable instructions!) to gather data, all of which will be recorded in the printed pages below. Step Three: Complete the lab work and calculations on your own, then turn it in at the beginning of recitation to the instructor on Wednesday, May 25. The graded lab will be returned to you the following week during recitation. If you have any questions regarding this assignment, please email ([email protected]) the instructor! Good luck on this assignment! Page I-7-1 / Determination of Ksp, ∆G˚, ∆H˚ and ∆S˚ for Ca(OH)2 Lab (in class) Determination of Ksp, ΔG˚, ΔH˚ and ΔS˚ for Ca(OH)2 The solubility of hydroxides is easily determined through a titration with a suitable acid (such as HCl). From the molar solubility, the solubility equilibrium constant, Ksp, can be calculated and from this the ΔG˚ for the dissolution of the material can be determined.
    [Show full text]