Acids and Bases

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Acids and Bases

• Chapter 19
• Chemistry X

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Review of Total and Net Ionic Rxns

• 1. Solutions of sodium sulfate and silver
  nitrate are mixed.

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Review of Total and Net Ionic Rxns

• 2. Solutions of beryllium chloride and sodium
  hydroxide are mixed.

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Review of Total and Net Ionic Rxns

• 3. A piece of magnesium ribbon is placed in a
  solution of nitric acid.

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Properties of Acids and Bases

• ACIDS
• Tastes sour
• Reacts w/active metals

• BASES
• Tastes bitter

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Properties of Acids and Bases

• ACIDS
• Turns litmus _____
• Phenophthalein _______

• BASES
• Turns litmus _____
• Phenolphthalein ________

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Properties of Acids and Bases

• ACIDS
• Conducts when in solution

• BASES
• Conducts when in solution

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Strong and Weak Acids

• Weak Acids
• Ionize partially
• (_______ bond to H)
• Have ____ Ka values
• Ex.

• Strong Acids
• Ionize completely
• (very _____ bond to H)
• Have ____ Ka values
• Ex.

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Polyprotic Acids

• Polyprotic acids only lose one H at a time.
• Ex. H2SO4 ?
• H3PO4 ?

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Self-ionization of water acidity

• Self ionization of water
• Write the equilibrium expression for the above
  reaction.
• _at_ 25C, K
• This means the ionization of water greatly favors
  _________________, thus the concentrations of H
  ions and OH- ions would be ____________.
• The ionization of water is endothermic. As temp.
  increases, K ____.

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Self-ionization of water acidity

• Q - Using the value of the equilibrium constant,
  calculate the concentration of H and OH- ions in
  water _at_ 25C.
• Q Given Kw 1.00 x 10-14, if H in 0.200 M
  HCl ______. Whats the OH- in that solution?

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Acidity and LeChatelier - HCl

• H2O ? H OH-
• If you add HCl, youre adding ____ and ____ ions.
  
• Thus shift _________
• H ________
• OH- _______

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Acidity and LeChatelier - NaOH

• H2O ? H OH-
• If you add NaOH, youre adding ____ and ____
  ions.
• Thus shift _________
• H ________
• OH- _______

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Acid/Bases Models

• Arrhenius Model
• Acid
• Base
• Ex. HCl ?
• NaOH ?

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Amphoteric Substances

• Examples of amphoteric substances

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Acid/Bases Models Bronsted-Lowry

• Bronsted-Lowry Model
• Acid
• Base
• Ex. HCl F- ?
• HCN NH3 ?

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Acid/Bases Models Bronsted-Lowry

• Ex. HCl F- ?
• HCN NH3 ?
• Conjugate Acid
• Conjugate Base -

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Proton-transfer Reactions

• HF(aq) H2O (l) ? F- (aq) H3O (aq)
• HCl (g) H2O (l) ? H3O (aq) Cl- (aq)
• H2SO4 (aq) H2O (l) ? _________ _________
• HCl (aq) NH3 (aq) ? _________ _________

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Proton-transfer Reactions

• 5) H3O (aq) ClO4- (l) HClO4 (aq)
  H2O (l)
• 6) CH3COOH (aq) H2O(l) _______
  _______
• 7) H2CO3 (aq) H2O(l) ? HCO3-(aq) H3O(aq)
• 8) HSO3-(aq) H3O(aq) ? ________ ________

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Proton-transfer Reactions

• 9) CN-(aq) HC2H3O2 (l) ? HCN(aq) C2H3O2-(aq)
  
• 10) HCN(aq) _________ ? HF(aq) _________
• Now go back up and circle the side favored.
• Q Would 2 or 4 have a greater tendency to
  form products? ______

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Concept Summaries (text box)

• HCl H Cl-
• CH3COOH H CH3COO-
• The stronger the acid, the ___________ the
  conjugate base.
• The weaker the acids, the ___________ the
  conjugate base.

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Concept Summaries (text box)

• TREND production of the stronger/weaker acid
  and stronger/weaker base is favored.
• (Note the strong acid and the strong base are
  always on ____________ side.)
• The extent the reaction occurs depends on the
  relative strengths of the acids and bases
  involved.

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Concept Summaries (text box)

• Questions
• Whats the conjugate base of HPO42-? _______
• HSO4-
• is the conjugate base of what? ___________
• Its the conjugate acid of what? __________

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Acid/Bases Models

• Lewis Model
• Acid
• Base
• Ex. HCN NH3 ?
• AlCl3 NH3 ?

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Terminology Clarifications

• Strong vs. Weak electrolytes
• Concentrated vs. dilute solutions
• Saturated vs. unsaturated solutions

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Calculating pH, H, OH-

• pH - log H H 10-pH

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Calculating pH, H, OH-

• pH - log H H 10-pH

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Calculating pH, H, OH-

• pH - log H H 10-pH

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Calculating pH, H, OH-

• pH - log H H 10-pH Kw 1.00 x 10-14
  HOH-

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Calculating pH, H, OH-

• pH - log H H 10-pH Kw 1.00 x 10-14
  HOH-

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Comparing H

• How do the following H compare?
• 0.10 M HCl 0.10 M HBr
• 0.10 M HCl 0.10 M H2SO4
• 0.10 M HNO3 0.10 M HF
• 0.10 M CH3COOH 0.10 M HCN
• Rank the following in order of increasing H
• HF, HNO3, HCl, HNO2
• H3PO4, HF, H2SO4, HI, HS-

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Neutralization Reactions

• Write the net ionic rxn for each of the
  following
• Hydrochloric acid reacts with a solution of
  lithium hydroxide.
• Hydrofluoric acid reacts with a solution of
  rubidium hydroxide.

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Titration

• Titration a process in which equivalent amounts
  of reactants are added to one another
• Ex. When mixing acids and bases, equivalent
  amounts means __________________
• Purpose Often an acid of _________
  concentration is used to determine
  _________________________________

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Titration

• If 20.0 mL of 0.100 M HCl is neutralized by
• a. 20.0 mL of ? M NaOH
• b. 10.0 mL of ? M NaOH
• c. 40.0 mL of ? M NaOH
• equivalence point
• indicator
• end point

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Titration Example Problems

• Key At the equivalence point
• 1) If it takes 15.7 mL of NaOH solution to
  completely neutralize 10.0 mL of 0.100 M HCl,
  what is the concentration of the original NaOH
  solution?

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Titration Example Problems

• 2) If it takes 19.5 mL of KOH solution to
  completely neutralize 20.2 mL of 0.150 M HCl,
  what is the concentration of the original KOH
  solution?

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Titration Example Problems

• 3) If it takes 18.3 mL of Ca(OH)2 solution to
  completely neutralize 14.0 mL of 0.200 M HNO3,
  what is the concentration of the original Ca(OH)2
  solution?

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Titration Example Problems

• 4) 0.150 moles of HI are neutralized by 30.0 mL
  of NaOH, what is the concentration of the
  original NaOH solution?

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Excess Problems

• Key
• Acid/Base excess problems are really just
  limiting reactant problems.
• When acids and bases react the net ionic equation
  is
• 1) If 0.100 moles of KOH and 0.100 moles of HCl
  are mixed, whats the pH of the resulting mixture?

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Excess Problems

• 2) If 0.100 moles of KOH and 0.150 moles of HCl
  are mixed, whats the pH of the resulting mixture?

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Excess Problems

• 3) If 15.0 mL of 0.200 M LiOH and 20.0 mL of
  0.150 M HI are mixed, whats the H, OH-, and
  pH of the resulting mixture?

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Summary of steps for excess problems

• 1) Calculate moles of H and OH-
• 2) Determine the number of moles of excess
  reactant
• 3) Divide the number of moles of excess reactant
  by total volume to determine the concentration of
  excess reactant.
• 5) To calculate H, OH-, or pH
• Kw 1.00 x 10-14 H OH- pH - log
  H

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REVIEW - differentiating between titration and
excess problems

• Titration Excess