1. Chemistry Jacqueline P. Hancock, B.S., M.Ed
Acids, Bases, & Salts
Chemistry
Jacqueline P. Hancock, B.S., M.Ed

2. 19.1
Acid-Base Theories
Bracken Cave, near San Antonio, Texas, is home to twenty to forty million bats. Visitors to the cave must protect themselves from the dangerous levels of ammonia in the cave. Ammonia is a byproduct of the bats’ urine. You will learn why ammonia is considered a base.

3. Properties of Acids and Bases
19.1
Properties of Acids and Bases
Acids
Acids taste sour, will change the color of an acid-base indicator, and can be strong or weak electrolytes in aqueous solution.
Citrus fruits contain citric acid.
Tea contains tannic acid.
Bases
Bases taste bitter, feel slippery, will change the color of an acid-base indicator, and can be strong or weak electrolytes in aqueous solution.
Antacids use bases to neutralize excess stomach acid.
Calcium hydroxide is a component of mortar.

4. Properties of Acids & Bases
Sour taste
Turn blue litmus RED
React with metals to produce hydrogen gas
React with carbonates to produce carbon dioxide
Strong or weak electrolytes in (aq) sol
Bases
Bitter taste
Turn red litmus Blue
Slippery to touch
Strong or weak electrolytes in (aq) sol

5. Three ways to define acids and bases
Arrhenius
Brønsted-Lowry
Lewis

6. Arrhenius Acids and Bases
19.1
Arrhenius Acids and Bases
Arrhenius Acids and Bases
Acids -produce hydrogen ions (H+) in aqueous solution.
Bases -produce hydroxide ions (OH–) in aqueous solution

7. Arrhenius Acids and Bases
19.1
Arrhenius Acids and Bases
Hydrochloric Acid
Hydrochloric acid is actually an aqueous solution of hydrogen chloride. Hydrogen chloride forms hydronium ions, making this compound an acid.

8. Arrhenius Acids and Bases pg 588
19.1
Arrhenius Acids and Bases pg 588
Arrhenius Acids
Monoprotic acids-contain one ionizable hydrogen
Diproti acids -contain two ionizable hydrogens
Triprotic acids- contain three ionizable hydrogens

9. Common Acids HCl Hydrochloric acid HNO3 Nitric acid
H2SO4 Sulfuric acid
H2CO3 Carbonic acid
HC2H3O2 Acetic acid
H3PO4 Phosphoric acid

11. Arrhenius Acids and Bases
19.1
Arrhenius Acids and Bases
Arrhenius Bases
Hydroxide ions are one of the products of the dissolution of an alkali metal in water.

12. Arrhenius Acids and Bases pg 589
19.1
Arrhenius Acids and Bases pg 589

13. Common Bases NaOH Sodium Hydroxide KOH Potassium Hydroxide
Ca(OH)2 Calcium Hydroxide
NH3 Ammonia
Al(OH)3 Aluminum Hydroxide
Mg(OH)2 Magnesium Hydroxide

14. Brønsted-Lowry Acids and Bases
19.1
Brønsted-Lowry Acids and Bases
Brønsted-Lowry Acids and Bases
Acid is a hydrogen-ion donor
Base as a hydrogen-ion acceptor.

15. Brønsted-Lowry Acids and Bases
19.1
Brønsted-Lowry Acids and Bases
Why Ammonia is a Base
Ammonia dissolves in water to form ammonium ions and hydroxide ions. In this reaction, the water molecule donates a hydrogen ion to the ammonia molecule. Explaining
Why is ammonia not classified as an Arrhenius base?

16. Brønsted-Lowry Acids and Bases
19.1
Brønsted-Lowry Acids and Bases
Conjugate Acids and Bases
A conjugate acid is the particle formed when a base gains a hydrogen ion.
A conjugate base is the particle that remains when an acid has donated a hydrogen ion.

17. Brønsted-Lowry Acids and Bases
19.1
Brønsted-Lowry Acids and Bases
A conjugate acid-base pair consists of two substances related by the loss or gain of a single hydrogen ion.
A substance that can act as both an acid and a base is said to be amphoteric.
Amphoteros-Greek word meaning partly one and partly the other.

18. Brønsted-Lowry Acids and Bases pg 591
19.1
Brønsted-Lowry Acids and Bases pg 591

19. Brønsted-Lowry Acids and Bases
19.1
Brønsted-Lowry Acids and Bases
A water molecule that gains a hydrogen ion becomes a positively charged hydronium ion (H3O+).
When sulfuric acid dissolves in water, it forms hydronium ions and hydrogen sulfate ions. Identify which ion is the conjugate acid and which he the conjugate base?

20. Lewis Acids and Bases Lewis Acids and Bases
19.1
Lewis Acids and Bases
Lewis Acids and Bases
Acid accepts a pair of electrons to form a covalent bond
Base donates a pair of electrons to form a covalent bond

24. for Conceptual Problem 19.1
Identify the reactants as either an acid or base
Identify the Lewis acid and Lewis base in each reaction
c. KOH + HBr KBr + H2O
d. HCl + H2O H3O+ +Cl-

25. Identify the Acids and Bases in the reactants only
BF3 + F BF4-
H2O + NH NH OH-
HCl + H2O H3O+ +Cl-
Ag+ +2NH [Ag(NH3)2]+

26. 19.1
Lewis Acids and Bases

27. Ion Product Constant for Water
19.2
Ion Product Constant for Water
Unrefined hydrochloric acid, commonly called muriatic acid, is used to clean stone buildings and swimming pools.
Sodium hydroxide, or lye, is commonly used as a drain cleaner.
Acids and bases have many uses in the home and in industry. a) Unrefined hydrochloric acid, commonly called muriatic acid, is used to clean stone buildings and swimming pools. b) Sodium hydroxide, or lye, is commonly used as a drain cleaner. Predicting How will each chemical affect the hydrogen-ion and hydroxide-ion concentration of an aqueous solution?

28. Hydrogen Ions from Water
19.2
Hydrogen Ions from Water
Self ionization of water, a proton (hydrogen
ion) transfers from one water molecule to another
water molecule.
Simple dissociation
The self-ionization of water. A proton (hydrogen ion) transfers from one water molecule to another water molecule. The result is one hydronium ion (H3O+) and one hydroxide ion (OH-).

29. Self- Ionization of Water (Dissociation)
H2O
Highly polar & in Constant motion
Pure water contains small concentrations of H+ & OH- as well as H2O molecules
High energy collisions allows transfer
Resulting in H3O+ and OH-

30. Ion Product Constant for Water
19.2
Ion Product Constant for Water
Ion Product Constant for Water
For aqueous solutions, the product of the hydrogen-ion concentration and the hydroxide-ion concentration equals 1.0 
Any aqueous solution in which [H+] and [OH-] are equal is described as a neutral solution.

31. Ion-Product Constant

32. @ 25oC
Equilibrium [H+] is 1x10-7 M
Equilibrium [OH-] is 1x10-7 M
Therefore the ion concentrations in pure water are equal making it Neutral

33. Ion Product Constant for Water
19.2
Ion Product Constant for Water
The product of the concentrations of the hydrogen ions and hydroxide ions in water is called the ion-product constant for water (Kw).

34. Ion Product Constant for Water
19.2
Ion Product Constant for Water
An acidic solution is one in which [H+] is greater than [OH-].
A basic solution is one in which [H+] is less than [OH]. Basic solutions are also known as alkaline solutions.

35. Acid or Base?
To determine whether a solution is acidic or alkaline(basic)
Use the exponent value for the ion given.
If [OH-] ….. Find the [H+]
Acid pH < [H+] > 1x10-7M
Neutral pH= [H+] = 1x10-7M
Basic pH> [H+] < 1x10-7M

36. Ion Concentration
To determine the ion concentration use the Ion-product constant for water
Rearrange the formula to isolate the unknown variable (solve for the missing variable)
Plug in the known values
Ion-Product Constant Formula

37. Practice Problems Classify as acidic, basic, or neutral
[H+]= 6x10-12 M
[OH-] = 3.0x10-2 M
[H+] = 2.0x10-7 M
[OH-]= 1.0x10-7 M
Base -12 < -7 Base -14/-2= < -7 Acid 2x10-7 > 1x10-7 Neutral =

38. Acid pH < 7.0 [H+] > 1x10-7M
Neutral pH= [H+] = 1x10-7M
Basic pH> [H+] < 1x10-7M

39. Quiz 19-2
1. If the [H+] in a solution is 1.0x10-9M, what is the [OH-] of this solution?
2. If the hydroxide-ion concentration of an aqueous solution is 1x10-5M, what is the [H+] in the solution? Is the solution acidic, basic, or neutral?

40. pH
1909 Danish scientist SØren SØrensen developed pH scale of (acid to base)
pH is the negative logarithm of the hydrogen-ion concentration of a solution
pH= -log[H+]
pOH= -log[OH-]
pH + pOH = 14

41. pH

42. pH meter

43. Calculating pH Calculation pH from [H+] pH= -log[H+]
Ex. [H+] = 1x10-8
Find the pH of each solution
[H+] =1x10-4M
[H+] = M
What are the pH values of the following solutions, based on their hydrogen-ion concentrations?
[H+] = 1x10-12M
[H+]= 0.045M

44. Calculating [H+] from pH Calculate [H+] for each solution pH= 5.0
Original formula:
pH = -log[H+]
Derived formula:
antilog(-pH)
Example:
pH= 6.38
=antilog(-6.38)
= 4.17 x10-7 M
Calculate [H+] for each solution
pH= 5.0
pH= 12.83
pH= 4.0
pH= 11.55

45. Practice Problems Calculating pH from [OH-] First find [H+]
Use Kw formula
Use pH= -log[H+]
First find [H+]
Second find –log[H+]
-log(H+ value)
Answer should be positive!!!
Calculate the pH of the solution
[OH-]= 4.3x10-5M
[OH-]= 4.5x10-11M
[H+] = 5.0x10-5M
[H+]= 8.3x10-10M

46. Homework … [H+] pH [OH-] pOH Acid or Base 1x10-4 12 5.6 2.6x10-8
9.8
5.0x10-3
4.23
4.35
1.85x10-7
4.0x10-11
3.5
8.75
6.78 x10-9
.05

47. Acid-Base Indicators Know Figure 19.2
An indicator(Hln) undergoes dissociation in a known pH range
Changes colors in different solutions
Limits of liquid indicators
Optimal temp 250C
Color sol. Can distort
Dissolved salts can affect dissociation
Paper indicators
pH meters
Know Figure 19.2
Thymol Blue
Bromphenol Blue
Bromcresol green
Methyl Red
Alizarin
Bromthymol Blue
Phenol Red
Phenolphtalein
Alizarin yellow R