1. Chapter 19 Acid and Base
Chemistry

2. Properties of Acids Acids effect indicators Blue litmus turns red
Acids taste sour (tart)
Acids effect indicators
Blue litmus turns red
Phenolphthalein is clear
Acids have a pH lower than 7

3. Properties of Acids Acids are proton donors (hydrogen ion, H+)
Acids react with active metals, produce H2
Acids react with metal carbonates and hydrogen carbonates, produce CO2
Acids neutralize bases, produce salt and H2O
Nonmetallic oxides become acids in aqueous solutions

4. What are acids? Many definitions exist…
Acids are compounds that give off hydrogen ions when dissolved in water.
They are recognized by having H+1 as the cation.
(formula begins with H)
The H+1 ion attaches to a water molecules to give rise to H3O+1 ions HYDRONIUM IONS

5. Protic Acids Monoprotic acids Diprotic acids Triprotic acids H3PO4 HCl
H2SO4
HC2H3O2
H2CO3
HNO3
Mono- can donates 1 hydrogen
Di – can donate 2 hydrogens
Tri- can donate 3 hydrogen
Polyprotic – includes Di- and Tri- protic acids

6. Acid Nomenclature Rules Naming-Review
Binary acids – H+1 and another nonmetal
(two elements)
Prefix = Hydro __ Suffix = ic HCl = hydrochloric
Ternary acids - H+1 and a polyatomic ion
Suffix = ic (-ate ion)
Suffix = ous (-ite ion)

7. Properties of Bases Bases feel slippery Bases effect indicators
Bases taste bitter
Bases feel slippery
Bases effect indicators
Red litmus turns blue
Phenolphthalein turns pink
Bases have a pH greater than 7

8. What are bases? Many definitions exist…
BASES are compounds that dissociate to form hydroxide ions when dissolved in water. 0H-1
They are recognized by having 0H-1 as the anion.
(formula end with 0H)
Bases are proton (hydrogen ion, H+) acceptors
Oxides of metallic elements usually form basic solutions

9. Ions in Solution
Pure water is neutral because equal numbers of hydrogen ions (H+1) and hydroxide ions (0H-1) are always present.

10. Arrhenius Model Ex: HCl + H2O  H3O+ (aq) + Cl – (aq)
Svante Arrhenius noticed that aqueous solutions of acids and bases were good conductors (electrolytes).
Traditional definition; requires water & focuses on products.
ACID- Increases hydrogen ions (H+ or H3O+) in water (ionizes)
Ex: HCl + H2O  H3O+ (aq) + Cl – (aq)
BASE - Increases hydroxide ions in water (OH-) (dissociates)
Ex: NaOH water  Na + (aq) + OH - (aq)

11. Bronsted-Lowry Model Bronsted –Lowry Acid = Proton Donor
Takes into account bases that do not contain a hydroxide group, such as ammonia.
Bronsted –Lowry Acid = Proton Donor
Bronsted-Lowry Base = Proton Acceptor
What is a proton =
These donors and acceptors produce partners called _____________
H+ ion lost from an acid
Conjugates

12. Bronsted-Lowry examples
HNO H2O  H3O NO3 –
Acid Base conjugate acid conjugate base
HCl NH3  NH Cl –
Acid Base conjugate acid conjugate base
1. HBr H2O 
H3O Br –
2. H2CO H2O 
H3O HCO3-
3. CN H2O 
HCN OH –
4. NH H2O 
NH OH –
Substances that can act as both acids and bases are said to be amphoteric.

13. POGIL Time!

14. The following substances act as Bronsted acids in water.
HF H F + H2O  H3O+ + F-
H2SO3 H2SO3 + H2O  H3O+ + HSO3-
Nitrous acid, HNO2 + H2O  H3O+ + NO2-
Acid Base C.A C.B
Acid Base C.A C.B
Acid Base C.A C.B

15. The following substances act as Bronsted bases in water.
Carbonate ion CO H2O  HCO OH-
Acetate ion C2H3O H2O  HC2H3O OH-
Ammonia NH3 + H2O  NH OH-
Base Acid C.A C.B
Base Acid C.A C.B
Base Acid C.A C.B

16. HF (aq) + H2O (l) F- (aq) + H3O+(aq)
Identify each reactant and each product in these equations as either a Bronsted acid or a Bronsted base.
HClO (aq) + H2O (l) ClO- (aq) H3O + (aq)
HF (aq) + H2O (l) F- (aq) H3O+(aq)
H2SO4 (aq) + SO32- (aq) HSO4 -(aq) HSO3- (aq)
Acid Base C.B C.A
Acid Base C.B C.A
Acid Base C.B C.A

17. POGIL Time!

18. Strengths of Acids Strong Acids Weak Acids Sulfuric acid, H2SO4
Phosphoric acid, H3PO4
Hydrochloric acid, HCl
Acetic acid, HC2H3O2
Nitric acid, HNO3

19. HCl(aq) + H2O(l)  H3O+(aq) + Cl-(aq)
Strong Acids
HCl is strong because it is very good at transferring an H+ ion to a water molecule.
In a 6 M hydrochloric acid solution, 100 % of the HCl molecules react with water to form H3O+ and Cl- ions.
HCl(aq) + H2O(l)  H3O+(aq) + Cl-(aq)

20. CH3CO2H(aq) + H2O(l) H3O+(aq) + CH3CO2-(aq)
Weak Acids
Vinegar is a weak acid because it is NOT very good at transferring H+ ions to water.
In a 1 M solution, less than 0.5% of the CH3CO2H molecules react with water to form H3O+ and CH3CO2- ions.
CH3CO2H(aq) + H2O(l) H3O+(aq) + CH3CO2-(aq)
It is considered weak because more than 99 % of the acetic acid molecules remain intact.

21. Strengths of Bases Strong Bases Weak Bases
Sodium hydroxide (lye), NaOH
Weak Bases
Potassium hydroxide, KOH
Magnesium hydroxide, Mg(OH)2
Calcium hydroxide (lime), Ca(OH)2
not very soluble
Ammonia, NH3

22. NaOH(s)  Na+(aq) + OH-(aq)
Strong Bases
NaOH is strong because it is very good at dissociating entirely into Na+ ion and OH -
NaOH(s)  Na+(aq) + OH-(aq)
Even though Ca(OH)2 is only slightly soluble in water, it is a strong base because all of the compound that dissolves dissociates into ions.

23. NH3(aq) + H2O(l) NH4+(aq) + OH-(aq)
Weak Bases
Ammonia is a weak base because it is NOT very good at transferring OH- ions to water.
NH3(aq) + H2O(l) NH4+(aq) + OH-(aq)
Equilibrium lies to the left because NH3 is weak and the conjugate base, OH- ion, is strong.

24. Strength Is Not Concentration
Although the terms weak and strong are used to compare the strengths of acids and bases, dilute and concentrated are terms used to describe the concentration of solutions.
To make the range of concentrations of possible hydronium or hydroxide ion concentrations (10–14 M to 1M) easier to work with, the pH scale was developed by S.P.L. Sørenson.

25. Neutralization
Milk of Magnesia contains magnesium hydroxide, Mg(OH)2, which neutralizes stomach acid, HCl.
2 HCl + Mg(OH)2
MgCl2 + 2 H2O

26. The Reaction Between Acids & Bases
Neutralization reaction: an acid and a base react in aqueous solution to produce a soluble salt and water
Salt
Ionic compound
Cation from base (Mg2+)
Anion from acid (Cl-)

27. Acids Neutralize Bases
Bases Neutralize Acids
Acids Neutralize Bases
Complete each neutralization reaction.
HCl (aq) + NaOH (aq) 
NaCl (aq) + HOH (l)
H2SO4 (aq) + Ca(OH)2(aq) 
CaSO4(aq) + 2HOH (l)
2HNO3 (aq) + Mg(OH)2 (aq) 
Mg(NO3)2 (aq) + 2HOH (l)
2HBr (aq) + Ba(OH)2 (aq) 
BaBr2 (aq) + 2HOH (l)
H2CO3 (aq) + Sr(OH)2 (aq) 
SrCO3 (aq) + 2HOH (l)
HClO4 (aq) + NaOH (aq) 
NaClO4 (aq) + HOH (l)

28. POGIL Time!

29. What is pH?
pH is a mathematical scale in which the concentration of hydronium ions in a solution is expressed as a number from 0 to 14.
much easier to work with than a range from 1 to 10–14 (each number is 10x the number preceding it)
The pH of a solution is the negative logarithm of the hydrogen ion concentration.
pH = -log[H+]

30. What is pOH?
pOH is a mathematical scale in which the concentration of hydroxide ions in a solution is expressed as a number from 14 to 0.
Runs opposite to the pH scale
The pOH of a solution is the negative logarithm of the hydroxide ion concentration.
pOH = -log[OH-]
pH + pOH = 14.00

31. pH and pOH

32. Using your calculator to determine pH
Enter the [H+]
Take the log of [H+] by pressing the key marked LOG.
Change the sign by pressing the +/- key.
Ex. Calculate the pH
[H+] = 1.0 x 10-7 M
[H+] = 1.0 x 10-2 M
[H+] = 3.0 x 10-6 M
[OH-] = 8.2 x 10-6 M
7.0
2.0
5.5
Determine pOH and subtract from 14.00
8.9

33. Using your calculator to determine [H+]
Enter the [-pH]
Take the antilog of [-pH] by pressing the 2nd key and then the key marked LOG.
Ex. Calculate the [H+]
pH = 6
pH = 3
pH = 4.7
pOH = 2.8
1 x10-6 M
1 x 10-3 M
2.0 x 10-5 M
6.3 x M
Subtract from and determine [H+].

34. Acid-base Titration
Acid-base indicator: chemical dyes whose colors are affected by acidic and basic solutions
Titration: method for determining the concentration of a solution by reacting a known volume of the solution with a solution of known concentration

35. Acid-base Titration
End point: the point at which the indicator changes color
Equivalence point: stoichiometric point at which the moles of H+ ion from the acid equal moles of OH- from the base

36. Titration Curves NH3+ HCl Strong CA NaOH + HCl CH3COOH + NH3
CH3COOH + NaOH
Strong CB

37. Calculating Molarity (#H+)MAVA = (#OH-)MBVB
What is the concentration (molarity) of a CsOH solution if 30.0 mL are neutralized by 26.4 mL of a M HBr solution?
HBr + CsOH  CsBr + HOH
(1 H+) (0.250 M) (26.4 mL) = (1OH-) MB (30.0 mL)
MB = M

38. Buffered Solutions
Buffers: solutions that resist changes in pH when limited amounts of acid or base are added
a buffer is a mixture of a weak acid and its conjugate base OR a weak base and its conjugate acid
the mixture of ions in solution resist changes in pH by reacting with any H+ or OH- ions added to the solution

39. Buffered Solutions
Buffer capacity: amount of acid or base a buffer solution can absorb without significant change in pH
ecosystems
blood