1. Chemistry Chapter 15
Acids and Bases

2. Definitions Arrhenius acids and bases
Acid: Substance that, when dissolved in water, increases the concentration of hydrogen/hydronium ions (protons, H+ or H3O+).
Base: Substance that, when dissolved in water, increases the concentration of hydroxide ions.

3. Salts Compounds that dissociate releasing neither H+ or OH- ions
Example:
KCl  K+ + Cl-

4. Definitions, cont’d Brønsted–Lowry: must have both
1. an Acid: Proton donor
and
2. a Base: Proton acceptor

5. Brønsted-Lowry acids and bases are always paired.
The Brønsted-Lowry acid donates a proton,
while the Brønsted-Lowry base accepts it.
Which is the acid and which is the base in each of these rxns?

6. What Happens When an Acid Dissolves in Water?
Water acts as a Brønsted–Lowry base and abstracts a proton (H+) from the acid.
As a result, a hydronium ion (H3O+) is formed.

7. Ionization of HCl and formation of hydronium ion, H3O+
H2O + HCl 
H3O+ + Cl-
Proton
acceptor
Proton
donor

8. A Brønsted–Lowry acid…
…must have a removable (acidic) proton.
HCl, H2O, H2SO4
A Brønsted–Lowry base…
…must have a pair of nonbonding electrons.
NH3, H2O

9. Properties of Acids Acids taste sour
Acids react with active metals, produce H2
Acids are electrolytes
Acids neutralize bases to produce a salt and water (neutralization)
Acids turn indicators different colors
litmus turns red
Acids have a pH lower than 7

10. Acids change Indicators
Blue litmus paper turns red in contact with an acid.

11. Acids React with Active Metals
Acids react with active metals to form salts and hydrogen gas.
Mg + 2HCl  MgCl2 + H2(g)

12. Acids Neutralize Bases
HCl + NaOH  NaCl + H2O
Neutralization reactions ALWAYS produce a salt and water.

13. Acids are Proton Donors
Monoprotic acids
Diprotic acids
Triprotic acids
H3PO4
HCl
H2SO4
HC2H3O2
H2CO3
HNO3

14. Uses ACIDS H3PO4 - soft drinks, fertilizer, detergents
H2SO4 - fertilizer, car batteries
HCl - gastric juice
HC2H3O2 - vinegar

15. Acids you must know: Strong Acids Weak Acids Sulfuric acid, H2SO4
Phosphoric acid, H3PO4
Hydrochloric acid, HCl
Acetic acid, HC2H3O2
Nitric acid, HNO3
Hydrobromic acid, HBr
Hydroiodic acid, HI
Perchloric acid, HClO4

16. Properties of Bases Solutions of bases feel slippery
Bases taste bitter
Solutions of bases feel slippery
Bases are electrolytes
Bases neutralize acids to produce a salt and
water
Bases affect indicators
litmus turns blue
Bases have a pH greater than 7

17. Examples of Bases Sodium hydroxide (lye), NaOH
Potassium hydroxide, KOH
Magnesium hydroxide, Mg(OH)2
Calcium hydroxide (lime), Ca(OH)2

18. Uses BASES NaOH - lye, drain and oven cleaner
Mg(OH)2 - laxative, antacid
NH3 - cleaners, fertilizer (most
common weak base)

19. Strong Acids vs. Weak Acids
Strong acids are assumed to be 100% ionized in solution (good proton donors).
HCl
H2SO4
HNO3
Weak acids are usually less than 5% ionized in solution (poor proton donors).
H3PO4
HC2H3O2
Organic acids

20. Strong Acid Dissociation

21. Weak Acid Dissociation
Notice the Double arrow that is used on a weak acid!

22. Concept Test
Which of the following "molecular" pictures best represents a concentrated solution of the weak acid HA? A B

23. pH Scale pH
a measure of the concentration of H3O+ ions in solution
measured with a pH meter or an indicator with a wide color range 7
INCREASING
ACIDITY
NEUTRAL
BASICITY 14

24. Acids Have a pH less than 7

25. Bases have a pH greater than 7

26. pH of Common Substances
pH Scale
pH of Common Substances

27. Neutralization Reaction
ACID + BASE  SALT + WATER
HCl + NaOH  NaCl + H2O =
Neutralization does not always mean pH = 7.

28. Neutralization Reaction
KOH + HNO3  H2O + KNO3
Acid?
Base?
Salt?
HNO3
KOH
KNO3

29. Products of Neutralization
HCl + NaOH 
NaCl + H2O
H2SO4 + Ca(OH)2 
CaSO H2O
HNO3 + KOH 
KNO3 + H2O
The products of neutralization are always a ______ and _______.
salt
water