1. 14.3 Acid-Base Reactions
Acids and Bases

2. POINT > Define conjugate acid-base pairs
POINT > Describe strength of acids and bases
POINT > Identify amphoteric species
POINT > Describe neutralization reactions

3. POINT > Define conjugate acid-base pairs
Recall that Brønsted–Lowry reactions must have a proton donor (acid) and a proton acceptor (base)
HCl + H2O  H3O Cl-

4. POINT > Define conjugate acid-base pairs
A Brønsted–Lowry acid must have a removable (acidic) proton:
HCl, H2SO4, CH3COOH

5. POINT > Define conjugate acid-base pairs
A Brønsted–Lowry base must have a pair of nonbonding electrons to accept the proton:
NH3, OH-, H2O

6. POINT > Define conjugate acid-base pairs
Reactions between acids and bases always yield their conjugate bases and acids
HCl + NH3  NH Cl-
When an acid donates a proton, its conjugate base is formed
Cl- is the conjugate base of the acid HCl

7. POINT > Define conjugate acid-base pairs
Reactions between acids and bases always yield their conjugate bases and acids.
HCl + NH3  NH Cl-
When an base accepts a proton, its conjugate acid is formed
NH4+ is the conjugate acid of the base NH3

8. POINT > Define conjugate acid-base pairs
Reactions between acids and bases always yield their conjugate bases and acids.
HCl + NH3  NH Cl-
The conjugate acid always has one more proton than its conjugate base

9. POINT > Define conjugate acid-base pairs
Reactions between acids and bases always yield their conjugate bases and acids.

10. HF + H2O ↔ F- + H3O+ WB CHECK: What is the conjugate base of HF?
What is the conjugate acid of H2O?
What is the conjugate base of H3O+?
What is the conjugate acid of F-?

11. POINT > Describe strength of acids and bases
Strong acids completely dissociate in water:
HCl + H2O  H3O Cl-
Their conjugate bases are therefore quite weak
HCl HBr HI H2SO4 HNO3 HClO4 HClO3
These are the strong acids

12. POINT > Describe strength of acids and bases
Weak acids dissociate only partially in water:
CH3COOH + H2O ↔ H3O CH3COO-
Their conjugate bases are stronger bases

13. POINT > Describe strength of acids and bases
The stronger an acid, the weaker its conjugate base
The stronger a base, the weaker its conjugate acid
The transfer of the proton in acid-base reactions favors the production of the weaker acid and base

14. POINT > Describe strength of acids and bases
The transfer of the proton in acid-base reactions favors the production of the weaker acid and base
HCl + H2O H3O Cl-
Compare the strengths of the acids (HCl and H3O+) and the bases (H2O and Cl-) using chart p. 459
The hydronium ion and chloride ion are weaker as acid and base respectively, so the arrow points…. 

15. POINT > Describe strength of acids and bases
The transfer of the proton in acid-base reactions favors the production of the weaker acid and base
CH3COOH + H2O H3O CH3COO-
Compare the strengths of the acids (acetic acid and H3O+) and the bases (H2O and acetate ion) using chart page 459
The acetic acid and water are weaker as acid and base respectively, so the arrow points…. 

16. HBr + H2O ? H3O+ + Br- WB CHECK:
Predict the direction a reaction will take, based on acid and base strength:
HBr + H2O ? H3O Br-

17. HBr + H2O  H3O+ + Br- WB CHECK:
Predict the direction a reaction will take, based on acid and base strength:
HBr + H2O  H3O Br-
HNO3 + H2O ? H3O NO3-

18. HBr + H2O  H3O+ + Br- WB CHECK:
Predict the direction a reaction will take, based on acid and base strength:
HBr + H2O  H3O Br-
HNO3 + H2O  H3O NO3-

19. HCO3- HSO4- POINT > Identify amphoteric species
As you may have noticed, water can act as an acid or a base. Such particles are called amphoteric:
They tend to be weak as acids and weak as bases
H2O
HCO3-
HSO4-

20. POINT > Describe neutralization reactions
Strong acids and strong bases react with each other in neutralization reactions
The protons released by strong acids combine with hydroxide ions released by strong bases to form water and a salt
HCl NaOH  H2O Na Cl-

21. WB CHECK:
Predict the products of the strong acid-strong base reaction:
HBr + Mg(OH)2  ?
HNO3 + KOH  ?

22. Homework:
Read Section 14.3 Pages
Section Assessment #1-3 Page 463