1. CHEM 121 Chapter 9
Winter 2014

2. Acids
produce H+ ions
Naming:
HCl (g) :
For polyatomic ion acids:

3. Bases
Bases: donate OH- ions
NaOH (s)

4. Acids & Bases Brønsted-Lowry Acids: HCl + H2O  Brønsted-Lowry Bases:
NH3 + H2O 
Conjugate acid-base pairs: HA + B

5. 3-minute Practice
What is conjugate acid of I-? What is the conjugate base of CH3COOH?

6. Strong Acids & Bases

7. Weak Acids & Bases H2O + NH3 +
Reaction will favor side with weaker acid

8. Dissociation Constants
Equilibrium constants for weak acids and bases
HA (aq) +
H2O (l) +

9. Dissociation of Water Water is ______________ H2O (l) + pure water:
Kw =

10. 3-minute Practice
Calculate the concentration of hydroxide ions in coffee, an aqueous solution containing 1.0 x 10-5 M H3O+ ions
Calculate the concentration of hydroxide ions in milk, which contains 5.0 x 10-7 M H3O+ ions

11. The pH Scale Scale from ________ Acidic Neutral Basic
Milk: [H3O+] = 5.0 x 10-7 M
pH of milk =

12. 3-minute Practice Calculate the pH of a solution that has…
[H3O+] = 1.0 x 10-8 M
[OH-] = 4.0 x 10-2 M

13. Neutralization Example: Reactants: Products: HCl (aq) + NaOH (aq) 
Molecular equation:
Net ionic equation:

14. Other Acid Reactions Example: carbonates bicarbonates Products:
NaHCO3 (aq) + HCl (aq) 

15. Acid & Active Metals
Example: calcium solid + HCl
Zn and HCl

16. Titration Indicator: Equivalence Point: End Point: Pink (basic)
Colorless
(acidic)
Equivalence Point:
End Point:

17. Titration Calculations
25.0 mL HCl solution is titrated with 15.5 mL M NaOH to reach the equivalence point. What is the molarity of the HCl?
mols base?
mols acid?
Acid concentration?

18. Buffers Acid must neutralize __________________________
Base must neutralize __________________________
Acid and base must not __________________________
Use a weak acid and its salt

19. Buffers CH3COOH (aq) + H2O (l) CH3COO - (aq) + H3O+ (aq)
You have prepared a buffer with 0.90 M CH3COOH and 1.2 M CH3COO-. (Ka for acetic acid = 1.8 x 10-5).
What is the equilibrium expression for this buffer?
What is the [H3O+] in this solution?
What is the pH of this solution?