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LecturePLUS Timberlake 1
Acids and Bases
Acids and Bases
LecturePLUS Timberlake 2
Arrhenius Acids and Bases
Acids produce H+ in aqueous solutions water
HCl H+(aq) + Cl- (aq)
Bases produce OH- in aqueous solutions
water
NaOH Na+(aq) + OH- (aq)
LecturePLUS Timberlake 3
Acids
Produce H+ (as H3O+) ions in water
Produce a negative ion (-) too
Taste sour
Corrode metals
React with bases to form salts and water
LecturePLUS Timberlake 4
Bases
Produce OH- ions in water
Taste bitter, chalky
Are electrolytes
Feel soapy, slippery
React with acids to form salts and water
LecturePLUS Timberlake 5
Learning Check AB1
Describe the solution in each of the following as: 1) acid 2) base or 3)neutral.
A. ___soda
B. ___soap
C. ___coffee
D. ___ wine
E. ___ water
F. ___ grapefruit
LecturePLUS Timberlake 6
Solution AB1
Describe each solution as:
1) acid 2) base or 3) neutral.
A. _1_ soda
B. _2_ soap
C. _1_ coffee
D. _1_ wine
E. _3_ water
F. _1_ grapefruit
LecturePLUS Timberlake 7
Learning Check AB2
Identify each as characteristic of an A) acid or B) base
____ 1. Sour taste
____ 2. Produces OH- in aqueous solutions
____ 3. Chalky taste
____ 4. Is an electrolyte
____ 5. Produces H+ in aqueous solutions
LecturePLUS Timberlake 8
Solution AB2
Identify each as a characteristic of an A) acid or B) base
_A_ 1. Sour taste
_B_ 2. Produces OH- in aqueous solutions
_B_ 3. Chalky taste
A, B 4. Is an electrolyte
_A_ 5. Produces H+ in aqueous solutions
LecturePLUS Timberlake 9
Some Common Acids
HCl hydrochloric acid
HNO3 nitric acid
H3PO4 phosphoric acid
H2SO4 sulfuric acid
CH3COOH acetic acid
LecturePLUS Timberlake 10
Learning Check AB3
Give the names of the following
A. HBr (aq) 1. bromic acid
2. bromous acid
3. hydrobromic acid
B. H2CO3 1. carbonic acid
2. hydrocarbonic acid
3. carbonous acid
LecturePLUS Timberlake 11
Solution AB3
A. HBr 3. hydrobromic acid
The name of a nonoxy acid begins with the prefix hydro- and ends with -ic acid. In a nonoxy acid, the negative anion end in -ide.
B. H2CO3 1. carbonic acid
The name of an oxyacid is named with the stem of the anion (carbonate) changed to
-ic acid
LecturePLUS Timberlake 12
Some Common Bases
NaOH sodium hydroxide
KOH potassium hydroxide
Ba(OH)2 ________________________
Mg(OH)2 ________________________
Al(OH)3 aluminum hydroxide
LecturePLUS Timberlake 13
Learning Check AB4
Match the formulas with the names:
A. ___ HNO2 1) hydrochloric acid
B. ___ Ca(OH)2 2) sulfuric acid
C. ___ H2SO4 3) sodium hydroxide
D. ___ HCl 4) nitrous acid
E. ___ NaOH 5) calcium hydroxide
LecturePLUS Timberlake 14
Solution AB4
Match the formulas with the names:
A. _4__ HNO2 1) hydrochloric acid
B. _5__ Ca(OH)2 2) sulfuric acid
C. _2__ H2SO4 3) sodium hydroxide
D. _1__ HCl 4) nitrous acid
E. _3__ NaOH 5) calcium hydroxide
LecturePLUS Timberlake 15
Learning Check AB5
Acid, Base Nameor Salt
CaCl2 ______ _________________
KOH ______ _________________
Ba(OH)2 ______ _________________
HBr ______ _________________
H2SO4 ______ __________________
LecturePLUS Timberlake 16
Solution AB5
Acid, Base Nameor Salt
CaCl2 salt calcium chloride
KOH base potassiuim hydroxide
Ba(OH)2 base barium hydroxide
HBr acid hydrobromic acid
H2SO4 acid sulfuric acid
LecturePLUS Timberlake 17
Bronsted-Lowry Acids
Acids are hydrogen ion (H+) donors
Bases are hydrogen ion (H+) acceptors
HCl + H2O H3O+ + Cl-
donor acceptor + -
+ +
LecturePLUS Timberlake 18
Chapter 9Acids and Bases
Acid-Base Neutralization
Buffers
Acid-Base Titration
LecturePLUS Timberlake 19
Neutralization Reactions
When acid and bases with equal amounts of hydrogen ion H+ and hydroxide ions OH- are mixed, the resulting solution is neutral.
NaOH (aq) + HCl(aq) NaCl + H2O
base acid salt water
Ca(OH)2 + 2 HCl CaCl2 + 2H2Obase acid salt water
LecturePLUS Timberlake 20
Neutralization
H3O+ and OH- combine to produce water
H3O+ + OH- 2 H2O
from acid from base neutral
Net ionic equation:
H+ + OH- H2O
LecturePLUS Timberlake 21
Ionic Equations for Neutralization
Write strong acids, bases, and salt as ions
H+ + Cl- + Na+ + OH- Na+ + Cl- + H2O
Cross out matched ions
H+ + Cl- + Na+ + OH- Na+ + Cl- + H2O
Write a net ionic reaction
H+ + OH- H2O
LecturePLUS Timberlake 22
Balancing Neutralization Equations
Write the equation for the neutralization
between magnesium hydroxide and nitric acid.
1. Write the formulas of the acid and base
Mg(OH)2 + HNO3
2. Balance to give equal OH- and H+
Mg(OH)2 + 2 HNO3
LecturePLUS Timberlake 23
3. Write the products:
Mg(OH)2 + 2HNO3 Mg(NO3)2 + H2O
salt water
(metal and nonmetal)
4. Balance products
Mg(OH)2 + 2 HNO3 Mg(NO3)2 + 2 H2O
LecturePLUS Timberlake 24
Learning Check N2
Select the correct group of coefficients for the
following neutralization equations
A. __ HCl + __ Al(OH)3 __AlCl3 + __
H2O
1) 1, 3, 3, 1 2) 3, 1, 1, 1 3) 3, 1, 1 3
B.__ Ba(OH)2 + __H3PO4 __Ba3(PO4)2 + __ H2O
1) 3, 2, 2, 2 2) 3, 3, 1, 6 3) 2, 3, 1, 6
LecturePLUS Timberlake 25
Solution N2
A. 3HCl + 1Al(OH)3 1AlCl3 + 3H2O
B. 3Ba(OH)2 + 2H3PO4 1Ba3(PO4)2 +
6H2O
LecturePLUS Timberlake 26
Learning Check N3
Write a balanced equation and calculate
the mL of 2.00 M H2SO4 required to
neutralize 50.0 mL of 1.00 M KOH?
___H2SO4 + ___KOH ___K2SO4 + H2O
1) 12.5 mL 2) 50.0 mL 3) 200. mL
LecturePLUS Timberlake 27
Solution N3
How many mL of 2.00 M H2SO4 are required to
neutralize 50.0 mL of 1.00 M KOH?
H2SO4 + 2KOH K2SO4 + 2H2O
0.0500 L x 1.00 mole KOH x 1 mole H2SO4 x
1 L 2 mole KOH
1 L x 1000 mL = 12.5 mL
2 mole KOH 1 L
LecturePLUS Timberlake 28
Learning Check N4
A 25 mL sample of phosphoric acid is neutralized by 40. mL of 1.5 M NaOH. What is the molarity of the phosphoric acid solution?
3NaOH + H3PO4 Na3PO4 + 3H2O
1) 0.45 M 2) 0.80 M 3) 7.2 M
LecturePLUS Timberlake 29
Solution S4
0.040 L x 1.5 mole NaOH x 1 mole H3PO4
1 L 3 mole NaOH
x 1 = 0.80 mol/L = 0.80 M
0.025 L
LecturePLUS Timberlake 30
Acids and Bases
Ionization of Water
The pH Scale
LecturePLUS Timberlake 31
Ionization of Water
Occasionally, in water, a H+ is transferred between H2O molecules
. . . . . . . .H:O: + :O:H H:O:H + + :O:H-
. . . . . . . . H H H
water molecules hydronium hydroxide ion (+) ion (-)
LecturePLUS Timberlake 32
Pure Water is Neutral
Pure water contains small, but equal amounts of ions: H3O+ and OH-
H2O + H2O H3O+ + OH-
hydronium hydroxide
ion ion
1 x 10-7 M 1 x 10-7 MH3O+ OH-
LecturePLUS Timberlake 33
Ion Product of Water Kw
[ ] = Molar concentration
Kw = [ H3O+ ] [ OH- ]
= [ 1 x 10-7 ][ 1 x 10-7 ]
= 1 x 10-14
LecturePLUS Timberlake 34
Acids
Increase H+
HCl (g) + H2O (l) H3O+ (aq) + Cl-
(aq)
More [H3O+] than water > 1 x 10-7M
As H3O+ increases, OH- decreases
[H3O+] > [OH-]H3O+
OH-
LecturePLUS Timberlake 35
Bases
Increase the hydroxide ions (OH-)
H2O
NaOH (s) Na+(aq) + OH- (aq)
More [OH-] than water, [OH-] > 1 x 10-7M
When OH- increases, H3O+ decreases
[OH] > [H3O+]
H3O+OH-
LecturePLUS Timberlake 36
Using Kw
The [OH- ] of a solution is 1.0 x 10- 3 M. What is the
[H3O+]?
Kw = [H3O+ ] [OH- ] = 1.0 x 10-14
[H3O+] = 1.0 x 10-14
[OH-]
[H3O+] = 1.0 x 10-14 = 1.0 x 10-11 M
1.0 x 10- 3
LecturePLUS Timberlake 37
Learning Check pH1
The [H3O+] of lemon juice is 1.0 x 10-3 M.
What is the [OH-] of the solution?
1) 1.0 x 103 M
2) 1.0 x 10-11 M
3) 1.0 x 1011 M
LecturePLUS Timberlake 38
Solution pH1
The [H3O+] of lemon juice is 1.0 x 10- 3 M.
What is the [OH-]?
[OH- ] = 1.0 x 10 -14 = 1.0 x 10-11 M 1.0 x 10 - 3
LecturePLUS Timberlake 39
Using the Calculator
1.0 x 10 -14
4.0 x 10-5
Enter 1.0 EE +/- 14 4.0 EE +/- 5
= 2.5 x 10 -10
LecturePLUS Timberlake 40
Learning Check pH2
The [OH-] of a solution is 5 x 10 -5 M. What is the [H3O+ ] of the solution?
1) 2 x 10- 5 M
2) 1 x 1010 M
3) 2 x 10-10 M
LecturePLUS Timberlake 41
Solution pH2
The [OH-] of a water solution is 5 x 10-5 M.
What is the [H3O+] in the solution?
[ H3O+] = 1.0 x 10 -14
5 x 10- 5
On some calculators:
1.0 EE +/- 14 5 EE +/- 5 = 2 x 10 -10 M
LecturePLUS Timberlake 42
Learning Check pH3
A.The [OH-] when [H3O+ ] of 1 x 10- 4 M
1) 1 x 10-6 M
2) 1 x 10-8 M
3) 1 x 10-10 M
B.The [H3O+] when [OH- ] of 5 x 10-9 M
1) 1 x 10- 6 M
2) 2 x 10- 6 M
3) 2 x 10-7 M
LecturePLUS Timberlake 43
Solution pH3
Kw = [H3O+ ][OH-] = 1.0 x 10 14
A. (3) [OH- ] = 1.0 x 10 -14 = 1.0 x 10 -10
1.0 x 10- 4
B. (2) [H3O+] = 1.0 x 10 -14 = 2 x 10 - 6
5 x 10- 9
LecturePLUS Timberlake 44
pH
Indicates the acidity [H3O+] of the solution
pH = - log [H3O+]
From the French pouvoir hydrogene
(“hydrogen power” or power of
hydrogen)
LecturePLUS Timberlake 45
In the expression for [H3O+]
1 x 10-exponent
the exponent = pH
[H3O+] = 1 x 10-pH M
pH
LecturePLUS Timberlake 46
pH Range
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Neutral
[H+]>[OH-] [H+] = [OH-] [OH-]>[H+]
Acidic Basic
LecturePLUS Timberlake 47
Some [H3O+] and pH
[H3O+] pH
1 x 10-5 M 5
1 x 10-9 M 9
1 x 10-11 M 11
LecturePLUS Timberlake 48
pH of Some Common Acids
gastric juice 1.0
lemon juice 2.3
vinegar 2.8
orange juice 3.5
coffee 5.0
milk 6.6
LecturePLUS Timberlake 49
pH of Some Common Bases
blood 7.4
tears 7.4
seawater 8.4
milk of magnesia 10.6
household ammonia11.0
LecturePLUS Timberlake 50
Learning Check pH4
A. The [H3O+] of tomato juice is 1 x 10-4 M.
What is the pH of the solution?
1) - 4 2) 4 3) 8
B. The [OH-] of an ammonia solution is
1 x 10-3 M. What is the pH of the solution?
1) 3 2) 11 3) -11
LecturePLUS Timberlake 51
Solution pH4
A. pH = - log [ 1 x 10-4] = -(- 4) = 4
B. [H3O+] = 1 x 10-11
pH = - log [ 1 x 10- 11] = -(- 11) = 11
LecturePLUS Timberlake 52
Learning Check pH5
The pH of a soap is 10. What is the [H3O+] of the soap
solution?
1) 1 x 10 - 4 M
2) 1 x 1010 M
3) 1 x 10 - 10 M
LecturePLUS Timberlake 53
Solution pH5
The pH of a soap is 10. What is the [H3O+]
of the soap solution?
[H3O+] = 1 x 10-pH M
= 1 x 10-10 M
LecturePLUS Timberlake 54
pH on the Calculator
[H3O+] is 4.5 x 10-6 M
pH = 4.5 x EXP(or EE) 6+/- LOG +/-
= 5.35
LecturePLUS Timberlake 55
Learning Check pH6
A soap solution has a [H3O+] = 2 x 10-8 M. What is the pH of
the solution?
1) 8
2) 7.7
3) 6
LecturePLUS Timberlake 56
Solution pH6
A soap solution has a [H3O+] = 2.0 x 10-
8 M. What is the pH of the solution?
B) 2.0 EE 8 +/- LOG +/- = 7.7
LecturePLUS Timberlake 57
Learning Check pH7
Identify each solution as
1. acidic 2. basic 3. neutral
A. _____ HCl with a pH = 1.5
B. _____ Pancreatic fluid [H+] = 1 x 10-8 M
C. _____ Sprite soft drink pH = 3.0
D. _____ pH = 7.0
E. _____ [OH- ] = 3 x 10-10 M
F. _____ [H+ ] = 5 x 10-12
LecturePLUS Timberlake 58
Solution pH7
Identify each solution as
1. acidic 2. basic 3. neutral
A. _1__ HCl with a pH = 1.5
B. _2__ Pancreatic fluid [H+] = 1 x 10-8 M
C. _1__ Sprite soft drink pH = 3.0
D. _3__ pH = 7.0
E. _1__ [OH-] = 3 x 10-10 M
F. _2__ [H+] = 5 x 10-12
LecturePLUS Timberlake 59
Acid RainUnpolluted rain has a pH of 5.6
Rain with a pH below 5.6 is “acid rain“
CO2 in the air forms carbonic acid
CO2 + H2O H2CO3
Adds to H+ of rain
H2CO3 H+ (aq) + HCO3-(aq)
Formation of acid rain:
1. Emission of sulfur and nitrogen oxides from the burning of fuels expecially coal with high S content, power stations, oil refineries, vehicles as well as bacterial decomposition, and lighting hitting N2
SO2 26 million tons in 1980
NO and NO2 22 million tons in 1980
Mt. St Helens (1980) 400,000 tons SO2
2. Reactions in the atmosphere form SO3
2SO2 + O2 2 SO3
3. Reactions with atmosphere water form acids
SO3 + H2O H2SO4 sulfuric acid
NO + H2O HNO2 nitrous acid
HNO2 + H2O HNO3 nitric acid
4. Effects of Acid Rain
Decline in fish populations in rivers and lasts due to toxic effect of Al leached from soil by acid rain
Extensive fish kills in spring from runoff due to accumulation of large amounts of acid on the snow
Dissolves minerals Mg, Ca, and K from the soil and waxy coatings that protect leaves from bacteria
Corrodes metals, textiles, paper and leather
LecturePLUS Timberlake 60
Sources of Acid Rain
Power stations
Oil refineries
Coal with high S content
Car and truck emissions
Bacterial decomposition, and lighting
hitting N2
LecturePLUS Timberlake 61
SO2 26 million tons in 1980
NO and NO2 22 million tons in 1980
Mt. St Helens (1980) 400,000 tons SO2
Reactions with oxygen in air form SO3
2SO2 + O2 2 SO3
Reactions with water in air form acids
SO3 + H2O H2SO4 sulfuric acid
NO + H2O HNO2 nitrous acid
HNO2 + H2O HNO3 nitric acid
LecturePLUS Timberlake 62
Effects of Acid Rain
Leaches Al from soil, which kills fish
Fish kills in spring from runoff due to
accumulation of large amounts of acid in
snow
Dissolves waxy coatings that protect leaves
from bacteria
Corrodes metals, textiles, paper and leather
LecturePLUS Timberlake 63
Chapter 9Acids and Bases
Strengths of Acids and Bases
Making Dilutions
LecturePLUS Timberlake 64
Strengths of Acids and Bases
Strong acids completely ionize (100%) in
aqueous solutions
HCl + H2O H3O+ + Cl- (100 % ions)
Strong bases completely (100%) dissociate into ions in aqueous solutions.
NaOH Na+ (aq) + OH-(aq) (100 % ions)
LecturePLUS Timberlake 65
NH3, A Bronsted-Lowry Base
When NH3 reacts with water, most of the reactants remain dissolved as molecules, but a few NH3 reacts with water to form NH4
+ and hydroxide ion.
NH3 + H2O NH4+(aq) + OH- (aq)
acceptor donor
+ +
LecturePLUS Timberlake 66
Strong and Weak Acids and Bases
Strong acids
HCl, HNO3 , H2SO4
Most other acids are weak.
Strong bases
NaOH, KOH, and Ca(OH)2
Most other bases are weak.
LecturePLUS Timberlake 67
Learning Check SW1
Identify each of the following as a
1) strong acid or base 2) weak acid
3) weak base
A. ___ HCl (aq)
B. ___ NH3(aq)
C. ___ NaOH (aq)
D. ___ H2CO3 (aq)
LecturePLUS Timberlake 68
Solution SW1
Identify each of the following as a
1) strong acid or base 2) weak acid
3) weak base
A. _1__ HCl (aq)
B. _3__ NH3(aq)
C. _1__ NaOH (aq)
D. _2__ H2CO3 (aq)
LecturePLUS Timberlake 69
Antacids
Used to neutralize stomach acid (HCl)
Many contain one or more weak bases
Alka-Seltzer: NaHCO3, citric acid, and aspirin
Di-gel: CaCO3 and Mg(OH)2
Gelusil: Al(OH)3 and Mg(OH)2
Maalox: Al(OH)3 and Mg(OH)2
Mylanta: Al(OH)3 and Mg(OH)2
LecturePLUS Timberlake 70
More Antacids
Milk of Magnesia: Mg(OH)2
Rolaids: AlNa(OH)2CO3
aluminum sodium dihydroxy carbonate
Tums: CaCO3
Tempo: CaCO3, Al(OH)3, Mg(OH)2
LecturePLUS Timberlake 71
Dilutions
Add water Volume increases. New concentration is less than initial
LecturePLUS Timberlake 72
Concentration of A Diluted Solution
A 25 mL sample of a 6.0 M KOH is diluted by adding 75 mL of water. Calculate the new concentration of the KOH solution.
Moles KOH = 0.025 L x 6.0 moles = 0.15 moles
1 L
New volume = 25 mL + 75 mL = 100. mL = 0.100 L
New molarity = 0.15 moles = 1.5 M
0.100 L
LecturePLUS Timberlake 73
Learning Check SW 2
A 125 mL sample of a 3.0 M HCl is diluted by adding 250 mL of water. The new concentration of the HCl solution is
1) 8.0 M
2) 1.5 M
3) 1.0 M
LecturePLUS Timberlake 74
Solution SW 2
3) 1.0 M
moles HCl = 0.250 L x 3.0 moles = 0.75 mole 1 L
new M = 0.75 mole 1.0 M HCl 0.750 L(new volume)
LecturePLUS Timberlake 75
Learning Check SW 3
A 50.0 mL sample of 15% sucrose solution is diluted by adding 200. mL of water. The new concentration of the sucrose solution is
1) 3.0 %
2) 7.5 %
3) 10. %
LecturePLUS Timberlake 76
Learning Check SW 3
A 50.0 mL sample of 15% sucrose solution is diluted by adding 200. mL of water. The new concentration of the sucrose solution is
1) 3.0 %
g sucrose = 50.0 mL x 15 g sucrose = 7.5 g
100 mL
new % = 7.5 g sucrose = 3.0 % sucrose
250 mL
(new volume)