Department of Chemistry

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• Department of Chemistry
• CHEM1010 General Chemistry
• Instructor Dr. Hong Zhang
• Foster Hall, Room 221
• Tel [phone]
• Email hzhang_at_tntech.edu

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CHEM1010/General Chemistry_______________________
__________________Chapter 7. (L26)-Acids and
Bases

• Todays Outline
• ..Review of acids and bases
• ..How to write acid and base molecules in
  molecular formula
• ..Common acids and bases
• ..Acidic and basic anhydrides
• nonmetal oxides Acidic anhydrides
• metal oxides Basic anhydrides
• ..Strong acids and strong bases
• ..Weak acids and weak bases

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Chapter 7. (L26)-Acids and Bases

• Chemical properties of acids and bases
• Chemical properties of acids
• -cause litmus indicator dye to turn red (turn
  blue with base)
• -taste sour
• -dissolve active metals (Zn, Fe, Cu, etc.),
  producing H2 gas
• -react with bases to form water and ionic
  after the DGM loading peak, compounds
  called salts

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Chapter 7. (L26)-Acids and Bases

• Chemical properties of acids and bases
• Chemical properties of bases
• -cause litmus indicator dye to turn blue (turn
  red with acid)
• -taste bitter
• -feel slippery on the skin
• -react with acids to form water and ionic
  compounds called salts

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Chapter 7. (L26)-Acids and Bases

• Acids and bases The Arrhenius theory
• -An acid is a molecule that will dissociate into
  a hydrogen cation (H, proton) and an anion in an
  aqueous solution
• Example HCl H Cl-
• -A base is a molecule that will give rise to a
  hydroxide anion (OH-) and a cation in an aqueous
  solution
• Example NaOH Na OH-
• -Neutralization reaction between an acid and a
  base is
• acid base salt water
• the salt is composed of the cation and anion
• Example
• H2SO4 2NaOH 2H2O 2Na SO42-

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Chapter 7. (L26)-Acids and Bases

• Acids and bases The Bronsted-Lowry acid-base
  theory
• According to the Bronsted-Lowry theory
• -an acid is a proton donor
• -a base is a proton acceptor
• Hydration of proton
• H H2O H3O
• H3O is called hydronium ion

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Chapter 7. (L26)-Acids and Bases

• Acids and bases The Bronsted-Lowry acid-base
  theory
• The theory to describe the ionization of HCl
• HCl(aq) H2O H3O Cl-(aq)
• The theory to describe the behavior of NH3
• NH3(aq) H2O NH4(aq) OH-(aq)
• The theory to describe the behavior of NaOH
• NaOH(aq) H2O Na H2O OH-(aq)
• H acceptor

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Chapter 7. (L26)-Acids and Bases

• How to write acid and base molecules in molecular
  formula
• ..Acids
• We commonly put H or proton on the left and the
  anion on the right (for inorganic acids).
• Example HCl, H2SO4, HNO3
• ..Bases
• We commonly put OH on the right and the cation
  on the left (for inorganic bases).
• Example NaOH, Ca(OH)2

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Chapter 7. (L26)-Acids and Bases

• Common acids
• ..Common acids (see Table 7.1 for more details)
• Name Molecular Formula Strength
• hydrochloric acid HCl strong
• sulfuric acid H2SO4 strong
• nitric acid HNO3 strong
• phosphoric acid H3PO4 moderate
• hydrogen sulfate HSO4- moderate
• carbonic acid H2CO3 weak
• acetic acid CH3COOH weak
• lactic acid CH3CHOHCOOH weak
• boric acid H3BO3 very weak
• hydrocyanic acid HCN very weak

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Chapter 7. (L26)-Acids and Bases

• Common bases
• ..Common acids (see Table 7.2 for more details)
• Name Molecular Formula Strength
• sodium hydroxide NaOH strong
• potassium hydroxide KOH strong
• lithium hydroxide LiOH strong
• calcium hydroxide Ca(OH)2 strong
• magnesium hydroxide Mg(OH)2 strong
• ammonia NH3 weak
• very low solubility although classified as a
  strong base

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Chapter 7. (L26)-Acids and Bases

• Acidic and basic anhydrides, nonmetal oxides
  Acidic anhydrides
• Nonmetal oxides can react with water to form
  acids.
• These nonmetal oxides are called acidic
  anhydrides.
• Example
• SO3 H2O H2SO4
• SO2 H2O H2SO3
• CO2 H2O H2CO3
• General form
• nonmetal oxide H2O ? acid
• anhydride means without water.

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Chapter 7. (L26)-Acids and Bases

• Acidic and basic anhydrides, metal oxides Basic
  anhydrides
• Metal oxides can react with water to form bases.
• These metal oxides are called basic anhydrides.
• Example
• CaO H2O Ca(OH)2
• BaO H2O Ba(OH)2
• Li2O H2O 2LiOH
• General form
• metal oxide H2O ? base

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Chapter 7. (L26)-Acids and Bases

• Strong acids and strong bases
• Strong acids Those completely dissociated into
  proton (H) and anion in water solution
• Example
• HCl H Cl- 100 dissociation
• HNO3 H NO3- 100 dissociation
• Strong bases Those completely dissociated into
  hydroxide (OH-) and cation
• Example
• NaOH Na OH- 100 dissociation
• KOH K OH- 100 dissociation

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Chapter 7. (L26)-Acids and Bases

• Weak acids and weak bases
• Weak acids Those incompletely or partially
  dissociated into proton (H) and anion in water
  solution
• Example
• CH3COOH H CH3COO- partial dissociation
• H2CO3 H HCO3- partial
  dissociation HCO3- H CO32- partial
  dissociation
• Weak bases Those incompletely or partially
  dissociated into hydroxide (OH-) and cation
• Example
• NH3 H2O NH4 OH- partial
  dissociation

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Chapter 7. (L26)-Acids and Bases

• Quiz Time
• Which of the following is an acidic anhydride?
• (a) CH4
• (b) BF3
• (c) H2O
• (d) SO3.

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Chapter 7. (L26)-Acids and Bases

• Quiz Time
• Which of the following is a typical reaction for
  an acidic anhydride?
• (a) CH4 O2 CO2 2H2O
• (b) N2 3H2 2NH3
• (c) H2O H OH-
• (d) CO2 H2O H2CO3

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Chapter 7. (L26)-Acids and Bases

• Quiz Time
• Which of the following is a basic anhydride?
• (a) CH4
• (b) N2
• (c) H2O
• (d) Li2O.

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Chapter 7. (L26)-Acids and Bases

• Quiz Time
• Which of the following is a typical reaction for
  a basic anhydride?
• (a) SO3 H2O H2SO4
• (b) N2 3H2 2NH3
• (c) H2O H OH-
• (d) CaO H2O Ca(OH)2