Acids and Bases

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Chapter 15

• Acids and Bases

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15.1 What are Acids and Bases?

• Objectives
• To name acids and bases.
• To write formulas for acids and bases.

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Rules for Naming Acids

• -ide ? hydro_____ic acid
• -ate ? _____ic acid
• -ite ? _____ous acid
• If a compound begins with hydrogen name it as an
  acid.

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Examples Naming Acids

• 1. HCl
• The anion is chloride (Cl-)
• For an anion ending in ide ? hydro___ic acid
• Therefore, the name is hydrochloric acid

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Examples Naming Acids

• 1. HCl
• The anion is chloride (Cl-)
• For an anion ending in ide ? hydro___ic acid
• Therefore, the name is hydrochloric acid
• 2. HNO3
• The anion is nitrate (NO3-)
• For an anion ending in ate ? ___ic acid
• Therefore, the name is nitric acid

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Examples Naming Acids

• 1. HCl
• The anion is chloride (Cl-)
• For an anion ending in ide ? hydro___ic acid
• Therefore, the name is hydrochloric acid
• 2. H2SO4
• The anion is sulfate (SO42-)
• For an anion ending in ate ? ___ic acid
• Therefore, the name is sulfuric acid
• 3. H2SO3
• The anion sulfite (SO32-)
• For an anion ending in ite ? ___ous acid
• Therefore, the name acid sulfurous acid

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Name the following compound HBr

1. Bromic acid
2. Bromous acid
3. Hydrobromic acid
4. Hydrobromous acid
5. None of the above

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Name the following compound HBr

1. Bromic acid
2. Bromous acid
3. Hydrobromic acid
4. Hydrobromous acid
5. None of the above

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Name the following compound H2C2O4

1. Chromic acid
2. Oxalate acid
3. Dihydrogen dicarbon tetraoxide
4. Oxalic acid
5. None of the above

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Name the following compound H2C2O4

1. Chromic acid
2. Oxalate acid
3. Dihydrogen dicarbon tetraoxide
4. Oxalic acid
5. None of the above

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Practice Naming Acids

• 1. H2SO3
• 2. HF
• 3. H3PO4
• 4. HNO3
• 5. HI

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Practice Naming Acids

• 1. H2SO3 sulfurous acid
• 2. HF hyrofluoric acid
• 3. H3PO4 phosphoric acid
• 4. HNO3 nitric acid
• 5. HI hydroiodic acid

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Examples Writing Formulas for Acids
H SO42-

• 1. Sulfuric acid
• The anion is sulfate (SO42-)
• The cation is H
• Criss-cross charges to get H2SO4
• 2. Carbonic acid
• The anion is carbonate (CO32-)
• The cation is H
• Criss-cross charges to get H2CO3

H2SO4
H CO32-
H2CO3
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Practice Writing Formulas for Acids

• 1. Hydrochloric acid
• 2. Nitric acid
• 3. Phosphorous acid
• 4. Hydroiodic acid

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Practice Writing Formulas for Acids

• 1. Hydrochloric acid HCl
• 2. Nitric acid HNO3
• 3. Phosphorous acid H3PO3
• 4. Hydroiodic acid HI

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Acids you should know
Strong Acids Weak Acids
Hydrochloric Acid Phosphoric Acid
Sulfuric Acid Acetic Acid
Nitric Acid
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Some Bases
Strong Bases Weak Bases
Sodium Hydroxide Ammonia
Potassium Hydroxide Sodium Carbonate
Calcium Hydroxide Potassium Carbonate
Barium Hydroxide
Sodium Phosphate
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15.1 What are acids and bases? continued

• Objectives
• To list properties of acids and bases.
• To define acid and base.
• To identify the acid, base, conjugate acid, and
  conjugate base in a chemical reaction.

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Properties of Acids

• Taste sour
• Form Hydronium Ions (H3O)
• Conduct electricity
• React with metals

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Properties of Bases

• Taste bitter
• Feel slippery
• Generate Hydroxide Ions (OH-)

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Acid

• Arrhenius Acid any substance that, when added to
  water, increases the hydronium ion (H3O)
  concentration
• Note H and H3O are used
  interchangeably

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Base

• Arrhenius Base generates hydroxide ions (OH-)
  when dissolved in water

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BrØnsted-LowRY Acid

• A substance that donates a proton (H) to another
  substance.

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BrØwnsted-lowry base

• A substance that accepts a proton (H).

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Conjugate Acid and Conjugate Base

• Conjugate Acid an acid that forms when the base
  gains a H
• Conjugate Base the base that forms when an acid
  loses an H

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Identify the conjugate base for the following
acids
Acid Conjugate Base
HCl Cl-
H2SO4
H3O
HSO4-
HOCl
H2PO4-
NH4
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Identify the conjugate base for the following
acids
Acid Conjugate Base
HCl Cl-
H2SO4 HSO4-
H3O H2O
HSO4- SO42-
HOCl OCl-
H2PO4- HPO42-
NH4 NH3
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Identify the conjugate acid for the following
bases
Conjugate Acid Base
NH4 NH3
HCO3-
HS-
Br-
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Identify the conjugate acid for the following
bases
Conjugate Acid Base
NH4 NH3
H2CO3 HCO3-
H2S HS-
HBr Br-
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Identify the acid, base, conjugate acid, and
conjugate base in the following chemical
reactions

• HCl OH- ? Cl- H2O
• acid base c. base c. acid
• 2. HNO3 OH- ? NO3- H2O
• 3. H2O HCO3- ? H2CO3 OH-

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Identify the acid, base, conjugate acid, and
conjugate base in the following chemical
reactions

• HCl OH- ? Cl- H2O
• acid base c. base c. acid
• 2. HNO3 OH- ? NO3- H2O
• acid base c. base c. acid
• 3. H2O HCO3- ? H2CO3 OH-
• acid base c. acid c. base

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Amphoteric Substances

• An amphoteric substance can donate AND accept
  protons.
• Example HCO3- is amphoteric
• HCO3- NH3 ? CO32- NH4
• Acid Base C. Base C. Acid
• HCO3- H3O ? H2CO3 H2O
• Base Acid C. Acid C. Base

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15.2 Acidity, Basicity, and pH

• Objective
• To calculate the concentration of the hydronium
  ion and the hydroxide ion.

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Self-Ionization of Water

• H2O(l) H2O(l) ? H3O(aq) OH-(aq)
• H3O OH- 1.00 x 10-7 M
• What is the Keq for water?

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Self-Ionization of Water

• H2O(l) H2O(l) ? H3O(aq) OH-(aq)
• H3O OH- 1.00 x 10-7 M
• What is the Keq for water?
• Keq H3OOH- (1.00 x 10-7)(1.00 x 10-7)
• Keq 1.00 x 10-14 Kw

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Summary

• Kw H3OOH-
• Kw 1.00 x 10-14

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Determining H3O and OH- using Kw

• Step 1 Write the Kw expression.
• Step 2 Determine concentrations.
• Step 3 Solve!

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Example

• What is OH- in a 3.00 x 10-5 M solution of HCl?
• Kw H3OOH-
• 1 x 10-14 (3.00 x 10-5) OH-
• OH- 3.33 x 10-10 M

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Practice

1. Calculate the hydronium ion concentration in an
   aqueous solution of KOH that has a hydroxide ion
   concentration of 7.24 x 10-4 M.

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Practice

1. Calculate the hydronium ion concentration in an
   aqueous solution of KOH that has a hydroxide ion
   concentration of 7.24 x 10-4 M.
2. What is the OH- in a 0.450 M solution of HNO3?

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Practice

• 3. What is H3O in a solution of NaOH whose
  concentration is 3.75 x 10-2 M?

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Practice

• 3. What is H3O in a solution of NaOH whose
  concentration is 3.75 x 10-2 M?
• 4. Calculate the hydroxide ion concentration of a
  0.200 M solution of HClO4.

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15.2 Acidity, Basicity, and pH continued

• Objective
• To calculate pH.

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pH

• pH A value used to represent acidity or
  alkalinity (basicity) of a solution.

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Measuring pH

• Indicators dyes that turn different colors in
  solutions of different pH
• Examples litmus paper, bromothymol blue, methyl
  orange, phenolphthalein

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Calculating pH

• pH -logH3O

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Example

• What is the pH of a solution with a 0.05 M
  hydronium ion concentration?
• pH -logH3O
• pH -log(0.05)
• pH 1.30
• Note pH does not have units.

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Practice

1. What is the pH of 0.00010 M solution of nitric
   acid?

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Practice

1. What is the pH of 0.00010 M solution of nitric
   acid?
2. Calculate the pH if H3O 5.0 x 10-3 M.

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Practice

1. What is the pH of 0.00010 M solution of nitric
   acid?
2. Calculate the pH if H3O 5.0 x 10-3 M.
3. What is the pH of a 0.2 M solution of a strong
   acid?

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15.2 Acidity, Basicity, and pH

• Objective
• To calculate pOH.

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Calculating pOH

• pOH -logOH-
• pH pOH 14

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Example

• What is the pH and pOH of 0.00010 M solution of
  HNO3?
• pH -logH3O
• pH -log(0.00010)
• pH 4.0
• pH pOH 14
• 4.0 pOH 14
• pOH 10

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Practice

1. What is the pH and pOH of a 0.0136 M solution of
   KOH?

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Practice

1. What is the pH and pOH of a 0.0136 M solution of
   KOH?
2. What is the pH and pOH of a 1.2 x 10-3 HBr
   solution?

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Practice

1. What is the pH and pOH of a 0.0136 M solution of
   KOH?
2. What is the pH and pOH of a 1.2 x 10-3 HBr
   solution?
3. What is the pH and pOH of a 2.34 x 10-5 NaOH
   solution?

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15.2 Acidity, Basicity, and pH

• Objective
• To calculate H3O and OH- from pH.

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Calculating H3O and OH- from pH

• pH -logH3O
• H3O 10-pH

pOH -logOH- OH- 10-pOH
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Example

• What are the concentrations of the hydronium and
  hydroxide ions in a sample of rain that has a pH
  of 5.05?
• H3O 10-pH
• H3O 10-5.05
• H3O 8.91 x 10-6 M
• Kw H3OOH-
• 1 x 10-14 (8.91 x 10-6)OH-
• OH- 1.12 x 10-9 M

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Practice

1. What is the hydronium ion concentration in a
   fruit juice that has a pH of 3.3?

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Practice

1. What is the hydronium ion concentration in a
   fruit juice that has a pH of 3.3?
2. A commercial window-cleaning liquid has a pH of
   11.7. What is the hydroxide ion concentration?

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Practice

1. What is the hydronium ion concentration in a
   fruit juice that has a pH of 3.3?
2. A commercial window-cleaning liquid has a pH of
   11.7. What is the hydroxide ion concentration?
3. If the pH of a solution is 8.1, what is the
   hydronium ion concentration?

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14.3 Neutralizations and Titrations

• Objective To determine the concentration of an
  acid or base used to reach the equivalence point
  in a titration.

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Neutralization Reaction(acid-base reaction)

• General Equation
• Acid Base ? Salt Water
• Example
• HCl NaOH ? NaCl H2O

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Titration

• Titration Method used to determine the
  concentration of an acid or base.

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Equivalence Point

• Equivalence Point Point at which the
  neutralization reaction is complete

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End Point

• End Point The instant at which the indicator
  changes color

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Titration Calculations

• MAVA MBVB
• where A is acid and B is base

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Example

• A student titrates 40.0 mL of an HCl solution of
  unknown concentration with a 0.5500 M NaOH
  solution. The volume of base solution needed to
  reach the equivalence point is 24.64 mL. What is
  the concentration of HCl solution?
• Acid (HCl) Base (NaOH)
• VA 40.0 mL VB 24.64 mL
• MA ? MB 0.5500 M
• MAVA MBVB
• MA (40.0 mL) (0.5500 M) (24.64 mL)
• MA 0.3388 M

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Practice

1. If it takes 25 mL of 0.05 M HCl to neutralize 345
   mL of NaOH solution, what is the concentration of
   the NaOH solution?

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Practice

1. If it takes 25 mL of 0.05 M HCl to neutralize 345
   mL of NaOH solution, what is the concentration of
   the NaOH solution?
2. If it takes 50 mL of 0.5 M KOH solution to
   completely neutralize 125 mL of hydrochloric acid
   solution, what is the concentration of
   hyrochloric acid solution?

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Practice

• 3. How much 1.5 M Ca(OH)2 is necessary to exactly
  neutralize 20.0 mL of 2.5 M sulfuric acid?

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Practice

• 3. How much 1.5 M Ca(OH)2 is necessary to exactly
  neutralize 20.0 mL of 2.5 M sulfuric acid?
• 4. A 25.0 mL sample was titrated to the endpoint
  with 15.0 mL of 2.0 M NaOH. What is the molarity
  of HCl?

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Practice

• 3. How much 1.5 M Ca(OH)2 is necessary to exactly
  neutralize 20.0 mL of 2.5 M sulfuric acid?
• 4. A 25.0 mL sample was titrated to the endpoint
  with 15.0 mL of 2.0 M NaOH. What is the molarity
  of Hcl?
• 5. How much 0.75 M HCl is needed to completely
  neutralize 25.0 mL of KOH?

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15.3 Neutralizations and Titrations

• Objective To determine the concentration of
  polyprotic acids needed to reach the equivalence
  point in a titration.

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Titrations with Polyprotic Acids

• MAVA MBVB
• With a twist
• MAVA (H) MBVB(OH-)

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Example

• What volume of a 1.366 M solution of NaOH would
  be required to titrate 47.22 mL of a 2.075 M
  solution of sulfuric acid?
• Acid (H2SO4) Base (NaOH)
• MA 2.075 M MB 1.366 M
• VA 47.22 mL VB ?
• H 2 OH- 1
• MAVA (H) MBVB(OH-)
• (2.075 M) (47.22 mL) (2) (1.366 M) (VB)(1)
• VB 143.5 mL

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Practice

1. How much 1.5 M NaOH is necessary to exactly
   neutralize 20.0 mL of 2.5 M phosphoric acid?

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Practice

1. How much 1.5 M NaOH is necessary to exactly
   neutralize 20.0 mL of 2.5 M phosphoric acid?
2. How much 0.5 M nitric acid is necessary to
   titrate 25.0 mL of 0.05 calcium hydroxide
   solution to the endpoint?