Acids and Bases

1
Acids and Bases
2
ACIDS
BASES

• electrolytes ?electrolytes

• Produces H30 in water ?produces OH- in water

• bitter taste, chalky

• sour taste

• turn litmus red

• turn litmus blue

• react with metals to form H2 gas

• slippery feel

• ammonia, antacid, baking soda

• vinegar, soda, apples, citrus fruits

3
Acids

• Arrhenius - In aqueous solution

• Acids form hydronium ions (H3O)

HCl H2O ? H3O Cl
acid
4
Base

• Arrhenius - In aqueous solution

• Bases form hydroxide ions (OH-)

NH3 H2O ? NH4 OH-
base
5
Bronsted-Lowry Acids

• Acids are proton (H) donors
• Bases are proton (H) acceptors
• HCl H2O H3O Cl-
• donor acceptor

6
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

7
Acid, Base Definitions
8
Learning Check AB1

• Describe the solution in each of the following
  as 1) acid 2) base or 3)neutral.
• A. ___soda
• B. ___soap
• C. ___ wine
• D. ___ water
• E. ___ grapefruit

1
2
1
3
1
9
Learning Check

• 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

A
B
B
Both
A
10
15.1 Acids Generate Hydronium Ions

• Strong Acids completely ionizes in water
• HNO3 H2O ? H3O NO3-
• Weak Acids partially ionizes in water
• HOCl H2O ? H3O ClO-
• Strong Acids MEMORIZE
• If it is not a strong acid then it is a weak
  acid!!
• HCl H2SO4 HNO3
• HBr HI HClO4

hydrochloric
sulfuric
nitric
hydroiodic
perchloric
hydrobromic
11
strong acid vs. weak acid
12
Bases Generate Hydroxide Ions

• Strong bases ionizes completely in water
• NaOH ? Na OH-
• Weak bases releases few hydroxide in water
• NH3 H2O ? NH4 OH-
• Strong Bases Memorize
• LiOH NaOH KOH
• Ca(OH)2 Ba(OH)2 Sr(OH)2
• If it is not a strong base then it is a weak
  base!!

Lithium hydroxide
Sodium hydroxide
Potassium hydroxide
Calcium hydroxide
Barium hydroxide
Strontium hydroxide
13
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)

1
3
1
2
14
Acid, Base Conjugates

• Acids are proton (H) donors.
• Bases are proton (H) acceptors.
• Conjugate acid base pair The pair of acid and
  base that differ by a H.
• Acid- conjugate base base- conjugate acid

HCl H2O ? Cl H3O
base
acid
15
Bronsted-Lowry Acids and Bases

• Acid Substance that donate a proton (H)
• Base Substance that accept a proton (H)
• Acid Base reaction H is transferred from the
  acid to the base.
•   Ex.
•  
• Conjugate acid base pair The pair of acid and
  base that differ by a H. Ex. ACID \ BASE

?
HX
Y
HY
X
Acid
Base
F
HF
Conjugate Acid add H
NO2
HNO2
C2H3O2
HC2H3O2
Conjugate Base subtract H
Memorize NH3 Base
Memorize NH4 Acid
16

• Amphoteric substance Substance that can either
  donate or accept a hydrogen ion.
•   Ex. H2O
•  
• Example Label the acids and bases, draw lines
  to connect the conjugate pairs.
• (1) NH3 H2O ? NH4 OH- (2) HF H2O
  ? F- H3O
•  

H
H
H2O
?
?
HSO4
HCO3
Acid
Base
Acid
Base
17

• Categorize each of the following as an Acid,
  Base, or Amphoteric and below each, write the
  conjugate acid or base.
• H2SO4 H2PO4- NH3 NO2- HSO4-

Acid
Ampho
base
Base
Ampho
HSO4
H3PO4
NH4
HNO2
H2SO4
HPO42
SO42
18
15.2 Acidity and Bascitiy and pH

• Water is both an acid and a base.

acid
base
C.A
C.B

• In pure water, the two ions must share the same
  concentration.
• Experiments show that this concentration is1.00
  10-7 M at 25C.
• H3O OH- 1.00 10-7 M

19
Acidity and Bascitiy

• The concentration of hydronium ions in a solution
  expresses its acidity.
• The concentration of hydroxide ions in a solution
  expresses its basicity.

• When the concentration of H3O goes up, the
  concentration of OH- goes down, and vice versa.

20
Water dissociation constant
OH (aq)
H2O(l) H2O (l)
?
H3O (aq)
Base
Acid
Keq H3OOH
Equilibrium constant
Kw H3OOH
Water dissociation constant
H3O OH- 1.00 10-7 M
Kw H3OOH 1 x 10 -14
In impure water (contains an acidic or basic
substance) If H3O gt 1.0 x 10-7 M, solution
is acidic. If H3O lt 1.0 x 10-7 M, solution
is basic If H3O 1.0 x 10-7 M, solution is
neutral.
21

• 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
• 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
• 2) 2 x 10- 6 M

22
What is OH- in a 3.00 10-5 M solution of HCl?

• HCl H2O ? H3O Cl-

3.00x10-5M
3.00x10-5M
H3O 3.00 10-5 M Kw H3OOH- 1.00
10-14
23
pH

• How Acidic Is an Acid?
• power of hydronium ion (pH) measure of the
  hydronium ion concentration in a solution
• 7
• less than 7 is acidic neutral greater than 7
  is basic
• Each unit of pH represents 10
• Ex. The difference between 3 and 5 is 100 times

24
pH and pOH

• H3O OH- Kw 1 x 10-14
• pH -log H3O pOH -log OH-
• pH pOH 14 10-pH H3O
• pH lt 7 acidic 10 pOH OH-
• pH gt 7 basic
• pH neutral

25
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

26
Solution pH4

• A. pH - log 1 x 10-4 4
• B. OH- 1 x 10-3
• H3O 1 x 10-11
• pH - log 1 x 10- 11 11

27
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
• H3O 10-pH M 10-10 M
• Acidic or Basic? . . .
• Basic

28
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

Steps . . .
29
Solution pH6

• A soap solution has a H3O 2.0 x 10-8 M.
  What is the pH of the solution?
• pH -log H3O so . . .
• B) /- LOG 2.0 EE /- 8 7.7
• Acidic or Basic? . . .
• Basic

30
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

1
2
1
3
1
2
31
pH on the Calculator

• H3O is 4.5 x 10-6 M
• pH /- LOG 4.5 EXP(or EE) /- 6 ENTER
• 5.35

32

• Given H3O1 3.02 x 10-8 and pOH 6.48,
• both just calculated, what is OH1-?
• OH- 10-pOH ? . . .
• 2nd log 6.48 3.31 x 10-7
• Can also do by Kw H3O1OH1-
• OH- 1.0 x 10-14/3.02 x 10-8 . . .?
• 1 EE 14 3.02 EE 8
  
• 3.31 x 10-7

33
Neutralization

• Neutralization Reactions
• Strong acids and strong bases react to form a
  salt and water
• HCl NaOH ? _____ _____
• Depends on the strength and amount of acids and
  bases used
• Neutralization does not mean pH 7.
• When acid and bases with equal amounts of
  hydrogen ion H and hydroxide ions OH- are mixed,
  the resulting solution is neutral.

NaCl H2O
34
Ionic Equations for Neutralization

• HCl NaOH HOH NaCl
• Write strong acids, bases soluble salts 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

35

• Equal volumes of 1 molar hydrochloric acid
• (HCl) and 1 molar sodium hydroxide base
• (NaOH) are mixed. After mixing, the
• solution will be
• A strongly acidic.
• B weakly acidic.
• C nearly neutral.
• D weakly basic.