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Chapter 8 Acids and Bases

Chemistry B11. Chapter 8 Acids and Bases. Acids and Bases. Acids: sour. Bases: bitter or salty. Acids and Bases. Arrhenius definition:. Acid: produces H 3 O +. CH 3 COOH(aq) + H 2 O(l) CH 3 COO - (aq) + H 3 O + (aq). H 3 O + (Hydronium ion):.

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Chapter 8 Acids and Bases

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  1. Chemistry B11 Chapter 8 Acids and Bases

  2. Acids and Bases Acids: sour Bases: bitter or salty

  3. Acids and Bases Arrhenius definition: Acid: produces H3O+ CH3COOH(aq) + H2O(l) CH3COO-(aq) + H3O+(aq) H3O+ (Hydronium ion): H+(aq) + H2O(l) H3O+(aq) Base: produces OH- H2O NaOH(s) Na+(aq) + OH-(aq) NH3(aq) + H2O(l) NH4+(aq) + OH-(aq)

  4. CH3COOH + NH3 CH3COO- + NH4+ acid base Conjugate base Conjugate acid Conjugate acid-base pair Conjugate acid-base pair Acids and Bases Bronsted and Lowry definition: (If H2O is not involved.) Acid: donates H+ (proton) Base: accepts H+ (proton)

  5. Acids and Bases HCl + H2O Cl- + H3O+ acid base Conjugate base Conjugate acid Conjugate acid-base pair Conjugate acid-base pair C6H5OH + H2O C6H5O- + H3O+ acid base Conjugate base Conjugate acid Conjugate acid-base pair Conjugate acid-base pair

  6. Acids and Bases Weak acid or base:is partially ionized in aqueous solution. produces less H+ and OH- CH3COOH(aq) + H2O(l) CH3COO-(aq) + H3O+(aq) NH3(aq) + H2O(l) NH4+(aq) + OH-(aq) Strong acid or base:is completely ionized in aqueous solution. produces more H+ and OH- HCl(aq) + H2O(l) Cl-(aq) + H3O+(aq) NaOH(aq) + H2O(l) Na+(aq) + OH-(aq)

  7. Acids and Bases A strong acid contains a weak conjugate base.

  8. Amphiprotic: itcan act as either acid or a base. HCl(aq) + H2O(l) Cl-(aq) + H3O+(aq) base NaOH(aq) + H2O(l) Na+(aq) + OH-(aq) acid Acids and Bases Monoprotic acids HCl Diprotic acids H2SO4 Triprotic acids H3PO4

  9. Anion : -ide ion + Hydro -ic acid Naming binary acids HF F-: flouride ion Hydroflouric acid HCl Cl-: chloride ion Hydrochloric acid H2S S2-: sulfuride ion Hydrosulfuric acid

  10. Naming ternary acids -ite ion -ous acid Anion: -ate ion -ic acid HNO2 NO2-: Nitrite ion Nitrous acid HNO3 NO3-: Nitrate ion Nitric acid H2CO3 CO32-: carbonate ion carbonic acid H2SO3 SO32-: sulfurite ion sulfurous acid

  11. [A-] [H3O+] Ka < 1 Ka = K [H2O] = Acid ionization constant [HA] Ka↑ or pKa ↓ Stronger acid Ionization constant HA + H2O A- + H3O+ [A-] [H3O+] K = not for strong acids Equilibrium constant [HA] [H2O] - Log Ka = pKa

  12. pH and pOH H2O + H2O OH- + H3O+ KW = [H3O+] [OH-] = (1×10-7) (1×10-7) [H3O+] [OH-] = 1×10-14 pH + pOH = 14

  13. pH and pOH pH = - log [H3O+] or -log [H+] pOH = - log [OH-] pH scale: 0 7 14 Base Neutral Acid [H3O+] ↑ [H3O+] ↓ and [OH-] ↑

  14. pH meter and pH indicators

  15. Nature & pH indicators Bigleaf Hydrangea In acidic soil In basic soil (alkaline)

  16. 2. Reaction with metal hydroxides: a salt and water are produced. KOH(aq) + 2HCl(aq) KCl(aq) + H2O(l) Acid Reactions 1. Reaction with metals (strong acids): a salt and H2 are produced. Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g)

  17. Acid Reactions 3. Neutralization: reaction between an acid and a base. A salt and water are produced. KOH(aq) + 2HCl(aq) KCl(aq) + H2O(l) 2NaOH(aq) + H2SO4(aq) Na2SO4(aq) + 2H2O(l) Strong acid reacts with strong base to produce the weaker acid and weaker base. (This is the direction of a reaction)

  18. B A MA× VA MB× VB = Coefficient A Coefficient B Titration (Neutralization reaction) MB: known VB: known MA: unknown VA: known Equivalence point: Equal amount of acid (H+) and base (OH-) (pH = 7). 2NaOH + 1H2SO4 2NaSO4 + 2H2O

  19. Buffers acid or base pH stays constant. Buffer Equal molar amount of a weak acid and a salt of weak acid. Equal molar amount of a weak acid and its conjugate base. 1 mole CH3COOH + 1 mole CH3COONa 1 mole CH3COOH + 1 mole CH3COO-

  20. Buffers pH of blood = between 7.35 and 7.45 Carbonate buffer H2CO3 / HCO3- Phosphate buffer H2PO4- / HPO42- Proteins buffer H2CO3 + OH-→ HCO3- + H2O HCO3- + H3O+ → H2CO3 + H2O

  21. HA + H2O A- + H3O+ If [AH] (weak acid) ≠ [A-] (conjugate base) Henderson-Hasselbalch equation: [A-] pH = pKa + log [HA] Buffers If [AH] (weak acid) = [A-] (conjugate base) pH of buffer = pKa of weak acid

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