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Acid-Base Theory

Acid-Base Theory

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Acid-Base Theory

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  1. Acid-Base Theory Ms. Murray

  2. Let’s start with the theorists! How should we define acids and bases? Lowry Picture Credit: http://www.geocities.com/bioelectrochemistry/lowry.htm Bronsted Picture Credit: http://www.geocities.com/bioelectrochemistry/bronsted.htm Lewis Picture Credit: http://www.albion.edu/chemistry/CH121/LewisRules.htm Arrhenius Picture Credit: http://scienceworld.wolfram.com/biography/Arrhenius.html

  3. Arrhenius Model • 1884 • Acid – a substance that produces H+ ions (protons) when dissolved in water • Sour taste • Low pH • Turns litmus paper red • Base – a substance that produces OH- ions when dissolved in water • Bitter taste • Slippery feel • High pH • Turns litmus paper blue Litmus Picture Credit: http://oldwww.mtlsd.org/senior/science/JPtachcinski/Lab_Proc/Basic%20Science%20Lab%20Techniques.htm Arrhenius Picture Credit: http://scienceworld.wolfram.com/biography/Arrhenius.html

  4. Bronsted-Lowry Model • 1923 • Acids – proton (H+) donors • Bases – proton acceptors Painting by Ellen Bronsted Lowry Bronsted Lowry Picture Credit: http://www.geocities.com/bioelectrochemistry/lowry.htm Bronsted Picture Credit: http://www.geocities.com/bioelectrochemistry/bronsted.htm

  5. Painting by Bronsted (1923) Picture Credit: http://www.geocities.com/bioelectrochemistry/bronsted.htm

  6. Lewis Model • Early 1920s • Acid – electron-pair acceptor • Base – electron-pair donor Lewis Picture Credit: http://www.albion.edu/chemistry/CH121/LewisRules.htm

  7. How do we measure how acidic or basic a compound is? We measure its… pH

  8. What is pH? • pH is a number that denotes the hydrogen (hydronium) ion concentration • pOH is a number that denotes hydroxide ion concentration • pH + pOH = 14 • If we’re talking about hydrogen ions and hydroxide ions, which theorist should we be thinking about?

  9. Arrhenius Picture Credit: http://scienceworld.wolfram.com/biography/Arrhenius.html

  10. pH Scale • Scale from 1-14 • Indicates the H+ concentration of a solution in Moles/L • pH = -log [H+] http://staff.jccc.net/PDECELL/chemistry/phscale.html

  11. pH = -log[H+] • An example: • Given that [H+] = 1.0 x 10^(-7) M, find pH • pH = - log (1.0 x 10^(-7)) = -(-7.00) = 7.00* • *the number of decimal places here = the number of significant figures in the original number

  12. Another example: • pH = -log[H+] • Given a pH of 6.00, calculate [H+] M • [H+] = 10^(-pH) • [H+] =10^(-6.00) • [H+] = 1.0 x 10^(-6.0) M

  13. pH In Your World The Good The Bad & The Really Ugly

  14. The Good - Hydrangea Picture Credit: http://www.flickr.com/photos/mshades/168884681/ Acceptable Use Policy: http://creativecommons.org/licenses/by/2.0/ Picture Credits: http://www.flickr.com/photos/cvalentine/439024324/ Acceptable use policy: http://creativecommons.org/licenses/by-nc-nd/2.0/

  15. The Bad 1968 1908 A castle in Westphalia, Germany. Built in 1702 Picture Credits: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AcidRain.html

  16. The Really Ugly! Picture Credit: http://www.waterencyclopedia.com/A-Bi/Acid-Rain.html

  17. “And You Will Know Us by The Trail of Dead Fish” - ldandersen Picture Credit: http://www.flickr.com/photos/ldandersen/181358675/ Acceptable Use Policy: http://creativecommons.org/licenses/by-nc/2.0/ Salton Sea

  18. Acid Rain Damage • Shenandoah National Park (1997) • - Photo by Bob Winterbottom Picture Credit: http://www.eco-systems.org/air_pollution_and_dying_forests.htm