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CHEM107: Inorganic Chemistry

Unit 6: Acids and Bases   In this unit, we will study the acids and bases of inorganic metals and nonmetals.  The concept of an acid as an electron acceptor and a base as an electron donor would greatly expand the number of compounds considered acidic or basic.  We will also review classical acids and bases, such as the Brønsted-Lowry definition of acids and bases.  We will in turn study the Lewis concept of acids and bases and introduce a new approach to understanding acidity and basicity, whereby acids and bases are defined as “hard” and “soft” (the hard/soft acid/base [HSAB] theory) based on their size, charge density, and polarizability.  We will also discuss the use of activity as a measure for the concentration of a solution, the acids of metal oxoacids (e.g., chromic acid), and the amphoteric behavior of certain chemical compounds (compounds that can be acids and bases).

Unit 6 Time Advisory
This unit should take you approximately 10 hours to complete.

☐    Subunit 6.1: 0.5 hours

☐    Subunit 6.2: 0.5 hours

☐    Subunit 6.3: 1.5 hours

☐    Subunit 6.4: 1.5 hours

☐    Subunit 6.5: 1 hour

☐    Subunit 6.6: 1 hour

☐    Subunit 6.7: 0.5 hours

☐    Subunit 6.8: 3 hours

☐    Subunit 6.9: 0.5 hours

Unit6 Learning Outcomes
Upon successful completion of this unit, students will be able to: - Differentiate between Brønsted-Lowry and Lewis acids and bases. - Explain the hard/soft acid/base (HSAB) theory. - Identify various inorganic acids and bases.

6.1 Molarity, Molality, and Standard State   - Reading: Wikipedia: “Molar Concentration,” “Molality,” and “Standard State” Links: Wikipedia: “Molar Concentration” (HTML), “Molality” (HTML), and “Standard State” (HTML)
 
Instructions: Please read these entire webpages for an overview of molarity, molality, and the standard state reference point. 
 
Terms of Use: This resource is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported license.

6.2 Activity   Note: The activity of a solution takes into account the interactions between solute particles in very concentrated solutions

6.3 Brønsted-Lowry Acids and Bases   - Reading: The Basics of General, Organic, and Biological Chemistry: “Chapter 10, Section 2: Brønsted-Lowry Definition of Acids and Bases” Link: The Basics of General, Organic, and Biological Chemistry: “Chapter 10, Section 2: Brønsted-Lowry Definition of Acids and Bases” (PDF)
 
Instructions: Read this section and then attempt the exercises at the end of the chapter. 

 Terms of Use: This text was adapted by The Saylor Foundation under
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  • Lecture: Academic Earth: MIT OpenCourseWare: Dr. Christopher Cummins: “Lewis and Bronsted Acid-Base Concepts” Link: Academic Earth: MIT OpenCourseWare: Dr. Christopher Cummins: “Lewis and Bronsted Acid-Base Concepts” (Adobe Flash)
     
    Also available in:
    iTunes or mp4
     
    Instructions: Please watch this entire video (approximately 43 minutes) for a greater understanding of Lewis and Brønsted acids and bases.  This video also covers subunits 6.3 and 6.4.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above. 

6.4 Lewis Acids and Bases   - Reading: The Basics of General, Organic, and Biological Chemistry: “Chapter 10, Section 1: Arrhenius Definition of Acids and Bases” Link: The Basics of General, Organic, and Biological Chemistry: “Chapter 10, Section 1: Arrhenius Definition of Acids and Bases” (PDF)
 
Instructions: Read this section and then attempt the exercises at the end of the chapter. 
 
Terms of Use: This text was adapted by The Saylor Foundation under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License without attribution as requested by the work’s original creator or licensee.

  • Reading: UC Davis: Chemwiki: “Lewis Concept of Acids and Bases” Link: UC Davis: Chemwiki: “Lewis Concept of Acids and Bases” (HTML or PDF)
     
    Instructions: Please read this entire webpage and then attempt the problems. You can download a PDF version by clicking “Make PDF” at the top of the page.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

6.5 Hard/Soft Acids and Bases   - Reading: University of Massachusetts, Lowell: Dr. Nancy De Luca: “Acids & Bases” Link: University of Massachusetts, Lowell: Dr. Nancy De Luca: “Acids & Bases” (PowerPoint)
 
Instructions: Please scroll down the page until you reach October 7 & 14 under Class Date.  Under the Topics heading, click the link for the Acids & Bases PowerPoint presentation.  Please read this entire presentation to gain an overview of the hard/soft acid/base theory.
 
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6.6 Inorganic Acids   - Reading: Washington University of St. Louis: “Inorganic Acids” Link: Washington University of St. Louis: “Inorganic Acids”(HTML)
 
Instructions: Please read this entire webpage for a listing of inorganic acids halides.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

6.6.1 Hydrogen Halides   - Reading: Chemguide: “The Acidity of the Hydrogen Halides” Link: Chemguide: “The Acidity of the Hydrogen Halides” (HTML)
 
Instructions: Please read this entire webpage for information on the synthesis and properties of hydrogen halides.  This material also covers subunits 6.8 (for hydrogen halides).
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

6.6.2 Oxoacids   - Reading: Wikipedia: “Oxoacid” Link: Wikipedia: “Oxoacid” (PDF)
 
Instructions: Please read this entire webpage to gain an understanding of oxoacids.  This material also covers subunits 7.1.2, 7.2.3, 7.3.5, 7.5.2, 7.6.3, and 7.7.3.
 
Terms of Use: The article above is released under a Creative Commons Attribution-Share-Alike License 3.0 (HTML).  You can find the original Wikipedia version of this article here (HTML).
 

6.7 Inorganic Bases   - Reading: Oklahoma State University: Laboratory Safety Manual: “Inorganic Bases” Link: Oklahoma State University: Laboratory Safety Manual: “Inorganic Bases” (HTML)
 
Instructions: Please read this entire section for a listing of common inorganic acids.  Please see subunits 7.1 through 7.3 for greater detail on these compounds.
 
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6.8 Enthalpy of Dissociation of Acids   - Reading: Purdue University: George M. Bodner's “The Relationship Between Free Energy and Equilibrium Constants”  Link: Purdue University: George M. Bodner's “The Relationship Between Free Energy and Equilibrium Constants”
 
Instructions: Please read through the entire section and work through practice problems 9 & 10.  For question 9, ΔG from problem 7 is -32.96 kJ.  Question 10 deals specifically with acid dissociation constants and Gibbs free energy.  Please remember that gibbs free energy is related to enthalpy via the following equation:  ΔG = ΔH – TΔS.  A review of this concept is found in a preceding section of the webpage listed.
 
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  • Reading: Jim Clark's Chemguide: “The Acidity of Hydrogen Halides” Link: Jim Clark's Chemguide: “The Acidity of Hydrogen Halides”
     
    Instructions: Please read through the entire webpage.  This material uses a thermodynamic approach to explain the relative acidity of the hydrogen halide series and explains why HF is a weak acid.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Web Media: Davidson College: David N. Blauch’s “Virtual Chemistry Experiments: Heat of Solution of Sulfuric Acid” Link:  Davidson College: David N. Blauch's “Virtual Chemistry Experiments: Heat of Solution of Sulfuric Acid” (HTML)
     
    Instructions: Please follow the specific instructions on the page in order to complete this experiment.  This experiment will help you visualize the release of enthalpy upon dissociation of acid in water.  Be aware that acid dissociation is often referred to as heat of solution.  If you need assistance calculating qrxn for the system, an explanation is given in “heat of solution of ammonium nitrate” experiment (link provided on page).   
     
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6.9 Periodic Trends in Amphoteric Structures   - Reading: Western Oregon University: “Periodic Trends and Oxides” Link: Western Oregon University: “Periodic Trends and Oxides” (HTML)
 
Instructions: Please scroll down to “Amphoteric Oxides” and then read this entire section for information on the inorganic acid electronegativity trend.
 
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Note: Amphoteric structures are able to act as acids and bases.