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Acids and Bases

Acids and Bases. Acid Properties. Sour taste (citrus fruits) Conduct electric current Change the color of indicators React with bases to produce salt and water: HCl + NaOH  H 2 O + NaCl Some react with metals to release H 2 gas: Mg + 2HCl  MgCl 2 + H 2. Naming Acids Review.

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Acids and Bases

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  1. Acids and Bases

  2. Acid Properties • Sour taste (citrus fruits) • Conduct electric current • Change the color of indicators • React with bases to produce salt and water: HCl + NaOH  H2O + NaCl • Some react with metals to release H2 gas: Mg + 2HCl  MgCl2 + H2

  3. Naming Acids Review • Ternary Acids (oxyacids) • HClO4 • Perchloric Acid • HClO3 • Chloric Acid • HClO2 • Chlorous Acid • HClO • Hypochlorius Acid • Binary Acids: • Hydroiodic Acid • HI • HF • Hydrofluoric Acid

  4. Base Properties • Bitter taste (coffee) • Feel slippery (soap) • Change the color of indicators • Caustic- attack the skin, cause severe burns • Conduct electric current

  5. Arrhenius Acids and Bases • Arrhenius Acid: A compound that produces H+ in solution. Ex:HCl (g) + H2O-------- H3O+ (aq) + Cl- (aq) • Arrhenius Base: A compound that produces OH- in solution. Ex: NaOH (s) --------- Na+ (aq) + OH- (aq) H2O

  6. Acid/Base Strength • Strong Acid: Ionizes completely in aq. soln. HCl H2SO4 HBr HNO3 HI HClO4 Strong Bases: Group 1 and 2 hydroxides

  7. Acid-Base Theories • Bronsted-Lowry: expands Arrhenius definition of acids and bases. • Bronsted-Lowry Acid: proton donor • Bronsted-Lowry Base: proton acceptor ex:HCl + NH3 NH4+ + Cl- Monoprotic B-L Acid B-L Base ex2: H3PO4 + H2O  H3O+ + H2PO4- Which is the B-L Acid? B-L Base?

  8. Lewis Acids and Bases • Based on bonding and structure and include substances that may not include Hydrogen. • Lewis Acid: electron pair acceptor • Lewis Base: electron pair donor ex: BF3 (aq) + F- (aq) BF4- (aq) Draw the dot structure for these substances and classify as a Lewis Acid or Base. Lewis Base Lewis Acid

  9. Conjugate Acids and Bases(Based on Bronsted-Lowry Classification) • Conjugate Base: The substance that remains after an B-L acid has given up a proton (H+). • Conjugate Acid: The substance formed when a B-L base has gained a proton. ex: HCl (aq) + H2O (l) Cl- (aq) + H3O+ (aq) Conjugate Base Conjugate Acid Acid Base • Table 15.6: The stronger the acid, the weaker its conjugate base. Equilibrium favors weak acid/base formation.

  10. Amphoteric Compounds • Can behave as an acid or base, depending on the strength of the acid or base with which they combine. • Examples: • Water • Ammonia

  11. Acid Reactions • Neutralization: HCl (aq) + NaOH(aq)  NaCl (aq) + H2O (l) • Acid Formation from Acid Anhydrides: SO3 (g) + H2O (l)  H2SO4 (aq) • Base Formation from Basic Anhydrides: Na2O (s) + H2O(l)  2NaOH Acid Rain Acid Anhydride Basic Anhydride

  12. Aqueous Solutions and pH • Self Ionization of Water • Water also supplies H3O+ and OH- ions. H2O (l) + H2O (l) H3O+ (aq) + OH- (aq) Conductivity Experiments show the concentrations of ions at 25 °C: 1.0 x 10-7 M 1.0 x 10-7 M • Ionization Constant of Water, Kw Kw = [H3O+][OH-] = [1.0 x 10-7 M][1.0 x 10-7 M] Kw = 1.0 x 10-14 M2 Constant at a given temperature

  13. Neutral, Acidic, and Basic Solutions • Neutral: [H3O+] = [OH-] • Acids: [H3O+] > [OH-] • Bases: [H3O+] < [OH-] Determine the hydronium and hydroxide ion concentrations in a 1 x 10-5 M HCl solution.

  14. pH Scale A more convenient way to express acidity • pH = -log[H3O+] • pOH = -log[OH-] • pH + pOH = 14.0 • Find the pH and pOH of a 1x10-10 M solution of acetic acid.

  15. Indicators and Titration • Acid-Base Indicators: Compounds whose colors are sensitive to pH (weak acid or base). • Titration: Method used to determine an unknown concentration of solution (pg.500)

  16. Equivalence Point • The point at which the 2 solutions used in a titration are present in equal amounts. • End Point: The point in a titration during which an indicator changes color.

  17. Molarity Determination from Titration • Because moles of acid=moles of base in a titration AND M = moles/Liter, THEN....... • MAVA/CA = MBVB/CB • In a titration, 27.4 ml of 0.015 M NaOH is added to a 20.0 ml sample of HCl solution of unknown concentration. What is the molarity of the acid solution

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