1. Antacids: 2B
This unit will introduce the chemistry needed to understand how antacids work
Section 2.4: Defining & Naming Acids & Bases
Section 2.5a Characteristics and pH calculations
Sections 2.5b Acid-Base Titrations

2. Section 2.4
We need to know how acids behave when talking about ant-acids!

3. What is an Acid? – Arrhenius Definition
A substance that produces hydrogen ions (H+1) when dissolved in water.
H+1 immediately reacts with water to make the hydronium ion, H3O+1 H O
water H O +1 H +1

4. How do Acids produce Hydronium?-
water
acid
Hydrogen cation with some anion

5. How do Acids produce Hydronium?- +1 H O

6. How do Acids produce Hydronium?- +1 H O
Hydronium ion
Anion

7. How to Identify an Acid H2SO4 HCl H2CO3 HNO3 HC2H3O2
Look for a hydrogen ion, “H+” as the first element in an aqueous covalent compound.
These are the 5 you must know:
H2SO4 HCl H2CO3 HNO3 HC2H3O2

8. Naming Binary Acids: Non-Oxygen Acids
These compounds have to :
Start with “H” (more than 1 “H” is OK, too).
Do not contain oxygen
To name these compounds:
Use “hydro____ic acid”
Fill in the blank with the root of the anion’s name

10. Example #1
HBr(aq)

11. HBr(aq) Hydrobromic acid No oxygen Use “hydro___ic” Hydrogen cation
It’s an acid
Hydrogen cation
HBr(aq)
Hydrobromic acid
Bromine
No oxygen
Use “hydro___ic”

12. Naming Oxyacids: contain oxygen
These compounds have:
Start with “H” (more than 1 “H” is OK, too).
Must contain oxygen
To name these compounds:
Use “___ic acids” for “-ate” anions
Use “___ous acids” for “-ite” anions
Do not use “hydro” with these…the word “acid” is how you know it begins with hydrogen, not “hydro-”

14. Example #2
HNO2(aq)

15. HNO2(aq) Nitrous acid Use “___ous” acid Hydrogen cation nitrite ion
It’s an acid
Hydrogen cation
HNO2(aq)
nitrite ion
“-ite” ion
Use “___ous” acid
Nitrous acid

16. Example #3
HC2H3O2(aq)

17. HC2H3O2(aq) acetic acid Use “___ic” Hydrogen cation acetate ion
It’s an acid
Hydrogen cation
HC2H3O2(aq)
acetate ion
“-ate” ion
Use “___ic”
acetic acid

18. Write the name for the following acids
Self Check HF
H2S
H3PO4
Example:
Write the name for the following acids

19. Write the name for the following acids
Answers HF
H2S
H3PO4
Hydrofluoric acid
Hydrosulfuric acid
Phosphoric acid
Example:
Write the name for the following acids

20. Writing the chemical formula for “Hydro-” acids
To write these formulas:
Write the cation, H+1
Write the anion symbol and charge
Balance the charges by adding the appropriate subscript to the hydrogen cation OR Criss Cross Method

21. Example #4
Hydrobromic acid

22. Does not contain oxygen
H+1
Hydrogen cation
Hydrobromic acid
Does not contain oxygen
Br-1

23. Does not contain oxygen
H+1
Hydrogen cation
Hydrobromic acid
Does not contain oxygen
H+1Br-1
Br-1
= 0
HBr
The compound is neutral.
Subscripts are not needed

24. Writing chemical formulas for “Oxyacids”
To write these formulas:
Write the cation H+1
If it is an “-ic” acid, determine the polyatomic ion ending in “-ate”
If it is an “-ous” acid, determine the polyatomic ion ending in “-ite”
Add subscript to the hydrogen cation to balance charges OR use Criss Cross Method

25. Example #5
Carbonic acid

26. From the “___ate” anion
Hydrogen cation
Carbonic acid
From the “___ate” anion
CO3-2

27. From the “___ate” anion
Hydrogen cation
H+ CO32-
= -1
Carbonic acid
H+ H+ CO32-
= 0
From the “___ate” anion
CO3-2
H2CO3

28. Example #6
Chlorous acid

29. From the “___ite” anion
Hydrogen cation
chlorous acid
From the “___ite” anion
ClO2-1

30. From the “___ite” anion
Hydrogen cation
Chlorous acid
H+ClO2-1
From the “___ite” anion
ClO2-1
= 0
HClO2

31. Write the formula for the following acids
Self Check
Phosphorous acid
Hydroiodic acid
Example:
Write the formula for the following acids

32. Write the formula for the following acids
Answers
Phosphorous acid
Hydroiodic acid
H3PO3 HI
Example:
Write the formula for the following acids

33. You Really Only Need to Know These Acids! Memorize them!
Hydrochloric acid HCl
Sulfuric acid H2SO4
Carbonic acid H2CO3
Nitric acid HNO3
Acetic acid HC2H3O2

34. What is a Base? – Arrhenius Definition
A substance that produces hydroxide ions, OH-1 in water
H2O
NaOH(s) Na+1(aq) + OH-1(aq) H O
water H O -1 +1 H Na O Na
Hydroxide Ion

35. How to Identify a Base NaOH Ca(OH)2 NH3
Look for an ionic compound that has a metal paired with the hydroxide ion, “OH-”
OR Look for the ammonia molecule
NaOH Ca(OH)2 NH3
**Do not assume all compounds ending in OH are bases: CH3OH is not a base but an alcohol

36. Naming & Writing Formulas for Metal Hydroxides
Follow the rules for ionic compounds.
The most common exception to this is ammonia, NH3
NH3 (ammonia) is a base even though it doesn’t contain “-OH” as the anion

37. Example #7
NaOH

38. Sodium
NaOH
Sodium Hydroxide
Hydroxide

39. Write the formula or name for each
Self Check
Ca(OH)2
KOH
Copper (II) hydroxide
Lithium hydroxide
Example:
Write the formula or name for each

40. Write the formula or name for each
Answers
Ca(OH)2
KOH
Copper (II) hydroxide
Lithium hydroxide
Calcium hydroxide
Potassium hydroxide
Cu(OH)2
LiOH
Example:
Write the formula or name for each

41. Another of definition of an ACID: According to Bronsted-Lowry
An acid is a hydrogen (proton) donor
The substance that remains after the hydrogen has been donated is called the conjugate base
Example: NH H2O  OH NH4+
acid conjugate base

42. Another definition of a BASE: According to Bronsted-Lowry
A base is a hydrogen (proton) acceptor
The substance that forms after the hydrogen has been accepted is called the conjugate aci
Example: NH H2O  OH NH4+
base conjugate acid

43. Bronsted-Lowry: The Big Picture

44. Conjugate Acid-Base Pairs
ACIDS & BASES WILL ALWAYS BE ON THE REACTANT SIDE
CONJUGATE ACIDS & BASES WILL ALWAYS BE ON THE PRODUCT SIDE
Practice Problems: Label the acid & base on the left side of the reaction and the conjugate acid & conjugate base on the right side.
a) HCl H2O  H3O Cl−
______ ______ ______ ______
b) HCO H2O  H2CO OH−
_____ ______ ______ ______
acid
base
C.A.
C.B.
base
acid
C.A.
C.B.

45. We need to know how acids behave when talking about ant-acids!
Section 2.5a:Characteristics & pH
We need to know how acids behave when talking about ant-acids!

46. Characteristics of Acids & Bases
Produce H3O+1 (hydronium ion) in water
Produce OH-1 (hydroxide ion) in water
Tastes sour
Tastes Bitter
React with active metals to form hydrogen gas
Feels slippery
Neutralizes a base to form salt and water
Neutralizes an acid to form salt and water
Both forms ions when dissolved: conducts electricity: They are called ELECTROLYTES

47. Section 2.5

48. Strength versus Concentration

49. strong acid – ALL acid molecules separate (dissociate) into [H+] ions in water; only ions present
Examples: HCl, HNO3, H2SO4
weak acid – Most acid molecules stay together, only a FEW separate into [H+] ions when in water; few ions present, mostly molecules
Examples: HC2H3O2 (vinegar) , H2CO3

50. Strong Acid Weak Acid

51. Strong versus Weak Acids
How many hydronium ion – anion pairs can you find? - + - 3 +
How many intact acid molecules can you find? + - 1
Strong acid
Most of the acid molecules have donated the H+1 to water

52. Strong versus Weak Acids+
How many hydronium ion – anion pairs can you find? 1
How many intact acid molecules can you find? - 3
Weak acid
Only a few of the acid molecules have donated the H+1 to water

53. Strong Acids vs. Weak Acids

54. Concentrated versus Dilute
solvent
solute
DILUTE
(low concentration)
Very little solute (what’s being dissolved) particles in solution
CONCENTRATED (higher concentration)
Lots of solute (what’s being dissolved) particles in solution

55. Combinations of Concentration & Strength
Concentrated
Dilute
Strong
A lot of acid/base added & all dissociates
Not much acid/base added, but all of what’s there dissociates
Weak
A lot of acid/base added, but little dissociates
Not much acid/base added and very little dissociates

57. Bases Strength & Concentration
Bases follow the same pattern as acids
A common misconception is acids are dangerous but bases are not!
Vinegar is an acid we eat…some of them are safe!
Sodium hydroxide is a very caustic base…not all of them are less harmful than acids!
The stronger and acid or base is & the more concentrated it is), the more dangerous it is for you!

58. Acids and Bases are Electrolytes
Acids and bases break apart into ions when dissolved in water
Free-floating ions in water conduct electricity
Acids & Bases are ELECTROLYTES
Strong acids and bases are strong electrolytes
- They produce lots of ions
Weak acids and bases are weak electrolytes
-they don’t produce lots of ions

59. The Power of the Hydrogen: pH
The pH scale to measure the acidity of a sample
Acids have a pH that are less than 7.0
Bases have pH values that are more than 7.0
Neutral is considered a pH of 7.0

60. Ways to measure pH Indicators change color based on pH
Liquid indicators – phenolphthalein or bromothymol blue
Bromothymol Blue: Acid: turns Yellow Base: turns blue
Phenolphthalein: Acid: stays clear Base: turns pink
pH meters or pH probes
Electronically determine pH and give a read-out
Acid
Base

61. Ways to Measure pH Indicators change color based on pH
Paper with a liquid indicator on it (pH paper or Litmus paper)
pH paper turns a color which matches
to a pH number
LITMUS PAPER (Mnemomic: See board!)
Blue Litmus stays blue in a base
but turns pink in an acid
Red Litmus stays red in an acid
but turns blue in a base

62. Practice Questions
1. Which of the following is an Arrhenius Acid? a. CuOH b. NH3 c. HC2H3O2 d. CaS 2. Which of the following substances has a bitter taste and slippery feel? a. CH3OH b. NH3 c. HC2H3O2 d. K2S

63. Practice Questions
3. Which of the following has a pH of 4? a. NaOH b. SO2 c. baking soda d. H2SO4 4. Which of the following substances will cause red litmus to turn blue? a. NaCl b. KOH c. H3PO4 d. H2CO3

64. Practice Questions
5. Which of the following will neutralize an acid? a. NaOH b. CH4 c. CaF2 d. HNO2 6. Which of the following substances will increase the number of hydroxide ions in solution? a. Fe2O3 b. H2SO4 c. NH3 d. H2CO3

65. Calculating pH pH scale – Logarithmic scale of the acidity
of a solution
pH has no units
The pH scale uses base “10”
The formula for calculating pH
The formula for calculating hydronium ion concentration
[ ] = concentration in Molarity

66. The “-” in the pH equation
Because pH is the negative log of concentration of hydronium, as concentration increases, the pH goes down.
The lowest pH is the highest concentration of hydronium ion

67. What does a “log” scale really mean?
Every change of 1 in pH shows a change of 10x in concentration of hydronium pH 4 3 2 1
Level of acidity increases
1000x more acidic
100x more acidic
10x more acidic

68. Example The pH of a solution changes from a pH of 5 to a pH of 3.
Did it increase or decrease in hydrogen ion concentration?
By what factor did it change?

69. Example 2 :Calculating pH
Find the pH if the concentration of [H3O+1] is 1.0x 10-8 M

70. An example of calculating pH
Find the pH if the concentration of [H3O+1] is 1.0 x 10-8 M
pH = 8.00

71. Example 3; Calculating hydronium concentration ([H3O+1])
Find the [H3O+1] if the pH is 5.0

72. An example of calculating hydronium
Find the [H3O+1] if the pH is 5.0
H3O+1 = 1 x 10-5 M

73. Auto-ionization of Water
Water molecules collide spontaneously and will split into ions. This is called auto-ionization
H2O + H2O  H3O+1 + OH-1
At 25°C the following is true:
[H3O+1] × [OH-1] = 1.0 × M2

74. Hydrogen Ion Concentration Values
If the hydrogen ion concentration is greater than hydroxide ion, the solution is ACIDIC with a pH < 7
[H+] > [OH-] or
[H+] > 1.0 x 10-7 M
If the hydrogen ion concentration is less than hydroxide ion, the solution is BASIC with a pH > 7
[H+] < [OH-] or
[H+] < 1.0 x 10-7 M
If the hydrogen ion concentration is equal to hydroxide ion, the solution is NEUTRAL with a pH = 7
[H+] = [OH-] = 1.0 x 10-7 M

75. Calculating pOH The formula for calculating pOH
The formula for calculating hydroxide ion concentration
To relate pH and pOH
[ ] = concentration in Molarity

76. Find the pOH if the concentration of [OH-1] is 1.0 × 10-5 M
Let’s Practice #1
Example:
Find the pOH if the concentration of [OH-1] is 1.0 × 10-5 M

77. Find the pOH if the concentration of [OH-1] is 1.0 × 10-5 M
Let’s Practice #1
Example:
Find the pOH if the concentration of [OH-1] is 1.0 × 10-5 M
pOH = 5.00

78. Let’s Practice # 2
Example:
Find the pOH if the pH is 4.

79. Let’s Practice #2
Example:
Find the pOH if the pH is 4.
pOH= 10

80. Find the [OH-1] if the [H+] is 1.0 x10-9M
Let’s Practice #3
Example:
Find the [OH-1] if the [H+] is 1.0 x10-9M

81. Let’s Practice #3: 2 ways to do this… 1st way
Example:
Find the [OH-1] if the [H+] is 1.0 x10-9
[OH-] = 1.0 x10-5 M

82. Let’s Practice #3: 2 ways to do this… 2nd way
Example:
Find the [OH-1] if the [H+] is 1.0 x10-9
pH = 9.00
pOH = 14
pOH = 5.00
[OH-] = 1.0 x10-5 M

83. What is the pH if the concentration of [OH-] = 1.0 x 10-7M
Let’s Practice #4
Example:
What is the pH if the concentration of [OH-] = 1.0 x 10-7M

84. What is the pH if the concentration of [OH-] = 1.0 x 10-7
Let’s Practice #4
Example:
What is the pH if the concentration of [OH-] = 1.0 x 10-7
pOH = 7
pH = 7

85. Section Section 2.5B
Acid- Base
Titrations

86. Titrations—Using Stoichiometry
Titration – A technique where the addition of a known volume of a known concentration solution to a known volume of unknown concentration solution to determine the concentration.
Use a buret to titrate unknown concentration of solutions.

87. Titrations—Using Stoichiometry
The titrant is the known concentration in the buret and the analyte is the unknown concentration in the flask.
Formula: naMaVa = nbMbVb
na= number of H+ in the acid formula
nb= number of OH- in the base formula
Ma= molarity of acid
Mb= molarity of base
V= volume

88. End Point vs. Equivalence Point
Equivalence Point (or Stoichiometric Point)
– When there are no reactants left over—they have all been reacted and the solution contains only products
the point where the acid and the base are equal in equal moles
moles acid = moles base

89. Importance of Indicators
Indicators – Paper or liquid that change color based on pH level.
End Point: point at which the indicator in the solution changes color
It signals the equivalence point and the stop of the titration
Always select an indicator that has a pH value close to that of the pH of the equivalence point of the titration.

91. Titration Process

92. Titration Problem #1
How many liters of 0.10 M NaOH is needed to react with L of 0.25 M HCl?

93. Titration Problem #2
What is the molarity of a Ca(OH)2 solution if 30.0 ml of the solution is neutralized by 20.0 ml of a 0.50 M solution of HCl?

94. Titration Problem #3
What volume of 2.0M solution of NH4OH is needed to neutralize 50.0 ml of a 0.50M solution of H2SO4?

95. Titration Curves Shows the changes of pH during a titration
Strong Base - Strong Acid
Weak Base - Strong Acid
Shows the changes of pH during a titration
Identifies the pH of the equivalence point
Strong Base - Weak Acid
Weak Base - Weak Acid

97. Titration curve for Titrating a strong acid with a strong base pH is always = 7
The titration curve graph shows the pH of the equivalence point. Take the vertical region and cut the length in half and then look to what pH value aligns to that point.

98. Titration curve for Titrating a strong base with an strong acid pH is always = 7

99. Titration curve for Titrating a weak acid with an strong base pH is >7