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Chapter 15 Acids bases

Chapter 15 Acids bases. acids. bases. Bitter Turns litmus blue Slippery Phenolphthalein- pink Corrosive Conducts electricity. Sour Turns litmus red Reacts with some metals to produce H 2 Phenolphthalein-clear Corrosive Conducts electricity. Arrhenius Acid.

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Chapter 15 Acids bases

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  1. Chapter 15 Acids bases acids bases Bitter Turns litmus blue Slippery Phenolphthalein-pink Corrosive Conducts electricity • Sour • Turns litmus red • Reacts with some metals to produce H2 • Phenolphthalein-clear • Corrosive • Conducts electricity

  2. Arrhenius Acid • produces hydronium ions (H3O+) hydrogen ions (H+) in water • dissociate • HCl(g) -----> H+(aq) + Cl-(aq) • HCl(g) + H2O(l) -----> H3O+(aq) + Cl-(aq) • HF(g) + H2O(l) -----> H3O+(aq) + F-(aq) • H2SO4(aq) + H2O(l) --------> H3O+(aq) + HSO4- (aq)

  3. Electrolytes dissociate into ions • Strong electrolyte –completelydissociates • K eq is large-lots of ions • Weak electrolyte partially dissociates • K eq is small, not many ions • Strong acid –completely dissociates • Ka is large-lots of ions • Weak acid • partially dissociates • Ka is small, not many ions • Ka =ionization constant

  4. Strong Acids [H3O+] • HCl • HNO3 • H2SO4 • HBr • HI • What is the hydronium ion [H3O+] concentration in a .10 M HCl solution? • HCl(g) + H2O(l) -----> H3O+(aq) + Cl-(aq)

  5. Weak Acids [H3O+] • What is the hydronium ion concentration in a .10 M HF solution? (Ka =6.8 x 10-4) • HF(g) + H2O(l) <-----> H3O+(aq) + F -(aq)

  6. Find Ka for weak acid • A .10 M weak acid has a hydronium ion concentration of 3.0 x 10 -4 M? What is the Ka? (ionization constant)

  7. Arrhenius Base • produces hydroxide (OH-) ion in water • NaOH(s) -----> Na+(aq) + OH-(aq) • Strong base-completely dissociates Kb is large-favors products • Weak base-partially dissociates Kb is small-favors reactants

  8. Strong Bases • NaOH • LiOH • KOH • RbOH • CsOH • Ca(OH)2 • Sr(OH)2 • Ba(OH)2 • What is the hydroxide ion concentration in a .10 M NaOH solution?

  9. Weak Base • NH3 is a weak base • NH3(g) + H2O(l) <-----> NH4+(aq) + OH-(aq) • What is the hydroxide ion concentration in a 0.10 M NH3 solution? (Kb for NH3 is 1.8 x 10 -5)

  10. Neutralization • HCl(aq) + NaOH(aq) -------> H2O(l) + NaCl (aq) • Acid + Base water + a salt • H+ (aq) + OH- (aq)-------> H2O (l) • H3O+ (aq) + OH- (aq)------->2 H2O (l) • Titrationprocess of adding an acid to a base or base to an acid • Equivalence point -moles of H3O+ (H+) = moles of OH- • Indicatorchanges color at a certain [H3O+] • End point when color changes • When titrating to neutrality End point and equivalence point should be very close (Choose an indicator that changes color when moles of H+ = moles of OH-) • When neutralizing a strong acid with strongbase the indicator phenolphthalein is usually used

  11. Titrationmolarity of an acid or base orvolume of an acid or base • What volume of .10 M HCl is needed to neutralize 10. mL of .20 M NaOH? • One to one ratio use MaVa=MbVb • Not one to one ratio use stoichiometry

  12. What volume of .10 M HCl is needed to neutralize 10. mL of .30 M Ca(OH)2?

  13. What is the molarity of an HCl solution if it takes 5.0 mL of .20 M NaOH solution to neutralize 8.0 mL of the HCl? • What is the molarity of an H2SO4 solution if it takes 5.0 mL of .20 M NaOH solution to neutralize 4.0 mL of the HCl?

  14. Bronsted-Lowry acids and basesdoes not need to be in water Bronsted Acid Bronsted Base Proton (H+) acceptor strong base –readily accepts a proton- large Kb weak base – does not readily accept a proton- small Kb • Proton (H+) donor • strong acid –readily donates a proton- large Ka • weak acid – does not readily donate a proton- small Ka

  15. HCl (aq) + H2O (l) <------> H3O+ (aq) + Cl- (aq) • NH3 (aq) + H2O(l)< -----> NH4+ (aq) + OH-(aq)

  16. Conjugate acid/base pair • To find conjugate base-remove H+ (proton) • Acid conjugate base • HF • HC2H3O2 • HSO4- • To find conjugate acid-add H+ (proton) • Baseconjugate acid • OH- • NH3 • CO32-

  17. H2O(l) + H2O(l) <-----> H3O+(aq) + OH- (aq) • Keq = Kw = 1.0 x 10 -14 • 1.0 x 10 -14 = [H3O+] [OH-] • Pure water [H3O+] = [OH-]

  18. 1.0 x 10 -14 = [H3O+] [OH-] • What is the hydronium ion concentration if the hydroxide ion concentration of a solution is 1.0 x 10 -2? • What is the hydroxide ion concentration if the hydronium ion concentration of a solution is 2.0 x 10 -4?

  19. Acid - more hydronium ions than hydroxide ions • Base - more –hydroxide ions than hydronium ions

  20. pH = –log[H3O+] • Log in base 10 • number to which 10 must be raised to equal that number • Log of .10 = ? • .10 = 10 -1 • log = -1 • Log of .010 = ? • .010 = 10 -2 • log = -2 • What is the pH of a solution that has a hydronium in concentration of .10 M? • pH =1 • What is the pH of a solution that has a hydronium in concentration of .010 M? • pH =2

  21. What is the pH of a solution if the hydronium ion concentration is 2.5 x 10 -3 M ? • Estimate • On calculator enter -log[H3O+] =

  22. Given pH find hydronium ion concentration • pH = 1 hydronium ion concentration = .10 M or 10-1 M • pH = 2 = = .010 M or 10-2 M • pH = 9 = 10-9 M • pH = 12 10-12 M • What is the hydronium ion concentration of a solution that has a pH of 4.8? • On calculator enter 10 x (2nd log button) - pH

  23. pH scale • 0_________________________________ 7_____________________________________14 • acid neutral base (alkaline) • H3O+ > OH- OH- > H3O+ • The lower the pH the more acidic The higher the pH the more basic

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