1. Created by C. Ippolito July 2007
Acids Bases Salts
19.1 Acid Base Theories
19.2 Hydrogen Ions and Acidity
19.3 Strengths of Acids and Bases
19.4 Neutralization Reactions
19.5 Salts in Solution
Created by C. Ippolito July 2007
Updated 12/8/2018

2. Created by C. Ippolito July 2007
Acid-Base Theories
Objectives
Define the properties of acids and bases
Compare and contrast acids and bases as defined by the theories of Arrhenius, Brønsted-Lowry, and Lewis
Created by C. Ippolito July 2007
Updated 12/8/2018

3. Properties of Acids and Bases
taste sour
burn
indicator color
litmus – red
btb – yellow
methyl orange – red
phenolphthalein - clear
electrolyte in solution
Bases
taste bitter
slippery
indicator color
litmus – blue
btb – blue
methyl orange – orange
phenolphthalein - pink
electrolyte in solution
Created by C. Ippolito July 2007
Updated 12/8/2018

4. Arrhenius Acids and Bases
hydrogen containing compounds
release H+ ions in aqueous solutions
HCl, HNO3, H2SO4, H3PO4, H2CO3
Monoprotic Acid (HCl, HNO3)
release one H+ ion
Diprotic Acid (H2SO4, H2CO3)
releases two H+ ion
Triprotic Acid (H2CO3)
Bases
release OH- ions in aqueous solutions
KOH, NaOH, Ca(OH)2, Mg(OH)2
Created by C. Ippolito July 2007
Updated 12/8/2018

5. Brønsted-Lowry Acids and Bases
hydrogen-ion donors
Base
hydrogen-ion acceptor
explains ammonia as a base
NH3(aq) + H2O(ℓ)  NH4+(aq) + OH-(aq)
Conjugate Acid
particle formed when a base gains a hydrogen ion - NH4+(aq)
Conjugate Base
particle formed when an acid donate a hydrogen ion - OH-(aq)
Amphoteric Substance
can act as both and acid or base
NH3(aq) + H2O(ℓ)  NH4+(aq) + OH-(aq) (water – acid)
HCl(aq) + H2O(ℓ)  H3O+(aq) + Cl-(aq) (water – base)
Created by C. Ippolito July 2007
Updated 12/8/2018

6. Created by C. Ippolito July 2007
Lewis Acids and Bases
Acids
accepts a pair of electrons during a reaction
Bases
donates a pair of electrons during a reaction
Created by C. Ippolito July 2007
Updated 12/8/2018

7. Hydrogen Ions and Acidity
Objectives
Define strong acids and weak acids
Describe how [H+] and [OH-] are related in an aqueous solution
Classify a solution as neutral, acidic, or basic given the hydrogen-ion or hydroxide-ion concentration
Convert hydrogen-ion concentrations into pH values and hydroxide-ion concentrations into pOH values
Describe the purpose of an acid-base indicator
Created by C. Ippolito July 2007
Updated 12/8/2018

8. Hydrogen Ions from Water
Self-Ionization
water molecules react to form ions
H2O(ℓ) + H2O(ℓ)  H3O
H2O(ℓ) ) + OH-(aq)
Neutral Solution
in pure water at 25°C
[H+(aq)] = [OH-(aq)]
only 1 x 10-7 M each
Created by C. Ippolito July 2007
Updated 12/8/2018

9. Ion Product Constant for Water (Kw)
Kw = [H+] x [OH-] = 1.0 x 10-14
Acidic Solution
[H+] is greater than [OH-]
[H+] is greater than 1 x 10-7
Basic Solution
a.k.a. alkaline solution
[H+] is less than [OH-]
[H+] is less than 1 x 10-7
Created by C. Ippolito July 2007
Updated 12/8/2018

10. Finding the [OH-] of a Solution
Created by C. Ippolito July 2007
Updated 12/8/2018

11. Created by C. Ippolito July 2007
The pH Concept
pH scale
range from 0 to 14
Acid Solution – pH<7 [H+] > 1 x 10-7 M
Neutral Solution – pH=7 [H+] = 1 x 10-7 M
Basic Solution – pH>7 [H+] < 1 x 10-7 M
Calculating pH
pH = -log[H+]
Neutral Solution
[H+] = 1 x 10-7
pH = -log(1 x 10-7) = -(log 1 + log 10-7)
pH = -(0.0 + (-7.0)) = 7
Calculating pOH
pOH = -log[OH-]
Created by C. Ippolito July 2007
Updated 12/8/2018

12. Relationship among [H+], [OH-], and pH
Created by C. Ippolito July 2007
Updated 12/8/2018

13. Calculating pH from [H+]
Created by C. Ippolito July 2007
Updated 12/8/2018

14. Created by C. Ippolito July 2007
Using pH to Find [H+]
Created by C. Ippolito July 2007
Updated 12/8/2018

15. Calculating pH from [OH-]
Created by C. Ippolito July 2007
Updated 12/8/2018

16. Created by C. Ippolito July 2007
Measuring pH
Acid-Base Indicators
change colors in acid/base solutions
Created by C. Ippolito July 2007
Updated 12/8/2018

17. Strengths of Acids and Bases
Objectives
Define strong acids and weak acids
Describe how an acid’s strength is related to the value of its acid dissociation constant
Calculate an acid dissociation constant (Ka) from concentration and pOH measurements
Order acids by strength according to their acid dissociation constants (Ka)
Order bases by strength according to their base dissociation constants (Kb)
Created by C. Ippolito July 2007
Updated 12/8/2018

18. Created by C. Ippolito July 2007
Strong and Weak Acids
Strong Acids
ionize completely in solution
Weak Acids
ionize slightly in solution
Acid Dissociation Constant (Ka)
the stronger the acid the larger the Ka value
Created by C. Ippolito July 2007
Updated 12/8/2018

19. Created by C. Ippolito July 2007
Strong and Weak Bases
Strong Bases
ionize completely in solution
Weak Bases
ionize slightly in solution
Base Dissociation Constant (Kb)
the stronger the base the larger the Kb value
Created by C. Ippolito July 2007
Updated 12/8/2018

20. Calculating Dissociation Constants
To find the Ka of a weak acid or the Kb of a weak base, substitute the measured concentrations of all substances at equilibrium into the Ka or Kb expression
Created by C. Ippolito July 2007
Updated 12/8/2018

21. Calculating a Dissociation Constant
Created by C. Ippolito July 2007
Updated 12/8/2018

22. Neutralization Reactions
Objectives
Define the products of an acid-base reaction
Explain how acid-base titration is used to calculate the concentration of an acid or a base
Explain the concept of equivalence in neutralization reactions
Describe the relationship between equivalence point and the end of a titration
Created by C. Ippolito July 2007
Updated 12/8/2018

23. Created by C. Ippolito July 2007
Acid-Base Reactions
Neutralization Reactions
acids and bases react in an aqueous solution to form a salt and water
HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(l)
1 mole acid : 1 mole base
H2SO4(aq) +2NaOH(aq)  Na2SO4(aq) + 2H2O(l)
1 mole acid : 2 mole base
2HCl(aq) + Ca(OH)2(aq)  CaCl2(aq) + 2H2O(l)
2 mole acid : 1 mole base
Equivalence Point
when the number of moles of hydrogen ions equals the number of moles of hydroxide ions
Created by C. Ippolito July 2007
Updated 12/8/2018

24. Finding the Number of Moles of an Acid in Neutralization
Created by C. Ippolito July 2007
Updated 12/8/2018

25. Created by C. Ippolito July 2007
Titration
process of adding a known amount of known concentration to determine the concentration of another solution
Standard Solution
solution of known concentration
End Point
point where indicator changes color showing neutralization has occurred
Created by C. Ippolito July 2007
Updated 12/8/2018

26. Determining the Concentration of an Acid by Titration
Created by C. Ippolito July 2007
Updated 12/8/2018

27. Created by C. Ippolito July 2007
Salts in Solution
Objectives
Describe when a solution of a salt is acidic or basic
Demonstrate with equations how buffers resist changes in pH
Created by C. Ippolito July 2007
Updated 12/8/2018

28. Created by C. Ippolito July 2007
Salt Hydrolysis
cations or anions of dissociated salt remove hydrogen ions from or donate hydrogen ions to water
Salts
formed by weak acid and strong base accept hydrogen ion to form BASIC SOLUTIONS
CH3COONa(aq) CH3OO-(aq) + Na+(aq)
CH3OO-(aq) + H2O(l)  CH3COOH(aq) + OH-(aq)
formed by strong acid and weak base donate hydrogen to form ACIDIC SOLUTIONS
NH4Cl(aq) NH4+(aq) + Cl-(aq)
NH4+(aq) + H2O(l)  NH3 (aq) + H3O+(l)
Created by C. Ippolito July 2007
Updated 12/8/2018

29. Created by C. Ippolito July 2007
Buffers
Buffer
solution in which the pH remains relatively constant with the addition of small amounts of acid or base
solution of weak acid and its salt or
solution of weak base and its salt
Buffer Capacity
amount of acid or base that can be added to buffer before a significant pH change occurs
Created by C. Ippolito July 2007
Updated 12/8/2018