Properties of Acids
1. Taste sour
2. Conduct electricity
3. Some are strong, some are weak electrolytes
4. React with metals to form hydrogen gas
5. Change indicators (litmus paper red)
6. React with hydroxides to form water and a salt
Properties of Bases
1. React with acids to form water and a salt.
2. Taste bitter
3. Feel slippery
4. Can be strong or weak electrolytes.
5. Change indicators (litmus paper blue)
Strong Acids
• HClO HNO
• H SO HI
• HBr HCl
• Completely dissociates in aqueous solution
4
2
3
4

Strong Bases
• LiOH Ca(OH)
• NaOH Sr(OH)
• KOH Ba(OH)
• Completely dissociates in aqueous solution
2
2
2
Arrhenius Definition
1. Acids produce H+ in aqueous solution
2. Bases produce OH- when dissolved in water
• Limitations:
1. Bases have to contain OH- (NH3 is not an Arrenius base)
2. Only aqueous solutions
1. An acid is a H+ donor.
2. A base is a H+ acceptor.
3. Acids & bases come in pairs.
4. When an acid dissolves in water it produces the hydronium ion (H3O+) .
HCl + H2O H3O+ + Cl-
• Conjugate Acid Base Pair: Two compounds that differ by a proton, H
+
• General Equation: Acid + Base  Conjugate acid + Conjugate base
•
Examples: HCO3- + HF H2CO3 + FTypes of Acids
1. Binary Acid: Hydrogen + one other element
2. Oxyacids: Hydrogen + non-metal + oxygen
• Form: H YO
n
m
Types of Acids
3. Polyprotic : An acid with more than one hydrogen.
• HN O
• H SO
• H PO
3
2
4
3
4
Factors that Affect Acid Strength
• The extent of dissociation of an acid HA is determined by the strength
and polarity of the HA bond.
A. The weaker the HA bond, the stronger the acid.
B. The more polar the HA bond, the stronger the acid.
Binary Acids, HA
• HA bond strength decreases down a group in the periodic table.
• Increase in the size of A down a group produces a weaker bond.
• HA bond polarity increases as the electronegativity of A increases.
• Rank the following from least acidic to most acidic.
-
-
HBr, HI, HF, HCl
• HF
• HCl
• HBr
• HI
Oxyacids, HnYOm
• Y is a non-metal
• Acid properties result from dissociation of
OH bond(s).
• Acid strength increases as the electronegativity of Y increases (weaker
OH bonds).
• Rank the following from least acidic to most acidic.
HClO, HIO, HBrO
• HI O
• HBrO
• HClO
• Acid strength increases with number of O’s bonded to Y.
• Rank the following from least acidic to most acidic.
HClO2, HClO4, HClO, HClO3
• HClO
• HClO
• HClO
• HClO
2
3
4
Which is stronger?
1. HI or H2Te
2. HClO4 or HClO3
3. HSO4- or HSeO4-
1. HI: Higher electronegativity
2. HClO4 : More O’s
3. HSO4- : Strength decreases down a group
Water
• Water ionizes (falls apart into ions)
• H O(l)H (aq) + OH (aq)
• Called the self ionization of water
• [H ] = [OH ] = 1 x10 M
+
2
+
•K
w
-
-
-7
is the ion product constant
Ion-Product Constant for Water
•K
•K
w
w
= [H+] [OH-] = 1 x 10-14 at 25° C
is constant in every aqueous solution.
• If [H ] > 10
+
-7
acidic
• If [H ] < 10
+
-7
basic
1. Calculate the [OH-] in a solution with a [H+] = 0.35 M.
[H+][OH-] = 1 x 10 -14
[H+] = 0.35 M
[OH-] = 1 x 10 -14
2. Is a solution with [OH-] = 8.5 x l0-5 acidic, basic, or neutral?
[H+][OH-] = 1 x 10 -14
[OH-] = 8.5 x 10 -5 M
[H+] = 1 x 10 -14
• Acidic, basic, or neutral? Acidic
pH Scale
• A measure of the acidity of a solution
• Equation: pH= - log[H ]
+
[H+] = 10-pH
• Acidic solutions, pH < 7
• Neutral solutions, pH = 7
• Basic solutions, pH > 7
pH and pOH
• pOH = - log [OH ]
• [OH ] = 10
• pH + pOH = 14
-
-
-pOH
pH and pOH Calculations
1. In a NaOH solution [OH-] = 2.9 x 10 -4 M. What is the pH?
pOH = - log [OH-]
= - log 2.9 x 10 -4
= 3.54
pH + pOH = 14
pH + 3.54 = 14
pH = 10.46
2. Oven cleaner has a pH of 13.4. What is the [OH-], pOH, and [H+]?
•
[H+] = 10-pH
= 10-13.4
= 3.98 x 10 -14
pH and pOH Calculations
• pH + pOH = 14
13.4 + pOH = 14
pOH = 0.6
pH and pOH Calculations
• [OH ] = 10
-
-pOH
= 10-0.6
= 0.251
•
•
Acid Dissociation Constant
General Equation:
HA + H2O(l)
H+ + ACreates an equilibrium
Acid Dissociation Constant
• K : Equilibrium constant
a
for a weak acid
• K = [H ] [A ]
a
+
-
Acid Dissociation Constant
• The larger the value of K , the stronger the acid
• K values can be determined from pH
a
a
Acid Dissociation Constant
• A 0.025 M solution of
HC3H5O3 has a pH = 2.75.
What is the Ka?
Acid Dissociation Constant
• Equilibrium problem.
• Set up an ICE box.
Acid Dissociation Constant
HC3H5O3 H + C3H5O3Acid Dissociation Constant
+
• Do you have a way to find “x”?
• pH will give you [H ]
+
Acid Dissociation Constant
• [H ] = 10
+
-pH
= 10-2.75
= 1.78 x 10 -3
x = 1.78 x 10 -3
Acid Dissociation Constant
Acid Dissociation Constant
Base Dissociation Constant
• K : Equilibrium constant
b
for a weak base
Base Dissociation Constant
• General Equation:
HB+ + OHBase Dissociation Constant
B + H2O(l)
• The larger the value of K , the stronger the base
• K values can be determined from pOH
b
b
Base Dissociation Constant
• Ammonia is a weak base. If the initial concentration is 0.150 M and [OH ]
-
at equilibrium is 0.0016, calculate Kb.
Base Dissociation Constant
+
NH3  NH4 + OHBase Dissociation Constant
• Do you have a way to find “x”?
• Given [OH ] at equilibrium in the problem.
-
Acid Dissociation Constant
Acid Dissociation Constant
Relationship Between
Ka and Kb
•
•
KaKb = Kw
KaKb = 1 x 10 -14
Relationship Between
Ka and Kb
•K >K
a
b
•
Ka < Kb
•
Ka = Kb
Acid Base Reactions
• All acid base reactions have the same general equation.
Acid Base Reactions
• Equation:
acid + base  salt + water
Acid Base Reactions
• Strength of acid & base determines the type of salt produced.
1. Strong acid & base
(neutralization reaction)
• Salt produced is neutral
2. Weak acid & strong
base:
• Salt produced is basic
3. Weak base & strong
acid:
• Salt produced is acidic
4. Weak acid & weak base
Acid Base Reactions
Acid Base Reactions
Acid Base Reactions
Acid Base Reactions
• Salt produced can be acidic, neutral, or basic.
Acid Base Titration
1. Analytical method in which a standard solution is used to determine the
concentration of an unknown solution.
Acid Base Titration
2. Titration curve:
A plot of pH of an acid or base solution versus the amount of acid or
base added.
Acid Base Titration
Acid Base Titration
3. Equivalence Point:
Point at which equal amounts of H+ & OH- have been added.
•
moles H+ = moles OH-.
Acid Base Titration
4. End Point:
A physical phenomenon associated with a color change at some pH.
Acid Base Titration
1. A 25 mL solution of sulfuric acid is completely neutralized by 18 mL of
M sodium hydroxide. What is the concentration of the sulfuric acid?
Acid Base Titration
Acid Base Titration
Acid Base Titration
Acid Base Titration
Acid Base Titration
2. A volume of 38.5 mL of 0.150 M NaOH neutralizes a 15 mL sample of
H3PO4 solution. What is the [H3PO4]?
Acid Base Titration
NaOH + H3PO4 
H2O + Na3PO4
Acid Base Titration
Acid Base Titration
Acid Base Titration
1