1. Acids and Bases By: Anthony Gates Regular Chemistry: Chapter 19
Honors Chemistry: Chapter 18

2. Think, Pair, Share What is an acid? What is a base?
Can you think of any acids or bases that are used in your everyday life?

3. Learning Objective
I can identify the acid, base conjugate acid, and conjugate base of a acid-base reaction.
I can define amphoterism.

4. Bronsted-Lowry Acids and Bases
Bronsted-Lowry Acid: a hydrogen-ion (proton) donor.
Bronsted-Lowry Base: a hydrogen-ion (proton) acceptor.
Hydrogen ion symbol: H+
Example:
NH3(aq) + H2O(l)  NH4+(aq) + OH-(aq)
Ammonia Water Ammonium Hydroxide
(base) (acid)

5. Practice Identify the acid and the base in the following reactions:
C2H4O2(aq) + H2O(l) C2H3O2-(aq) + H3O+(aq)
Acid Base
CH3NH2(aq) + H2O(l) CH3NH3+(aq) + OH-(aq)
Base Acid

6. Conjugate acids and bases
Conjugate Acid: the particle produced after the base has accepted a proton.
Conjugate Base: the particle produced after the acid has donated a proton.
Example:
NH3(aq) + H2O(l) NH4+(aq) + OH-(aq)
Conjugate Conjugate
Acid Base

7. Practice
Identify the conjugate acid and the conjugate base in the following reactions:
C2H4O2(aq) + H2O(l) C2H3O2-(aq) + H3O+(aq)
Conjugate Conjugate
Base Acid
CH3NH2(aq) + H2O(l) CH3NH3+(aq) + OH-(aq)
Acid Base

8. Auto-Ionization of Water
H2O + H2O  H3O+ + OH-
At 25, [H3O+] = [OH-] = 1 x 10-7M

9. Amphoterism
Amphoterism: the ability of a substance to act like both an acid and a base.
Water is amphoteric

10. Bellwork
Turn to a partner and give a definition of an acid and a base in your own words.
Turn to a different classmate and give a definition of a conjugate acid and conjugate base in your own words.

11. Learning Objective I can write an acid or base dissociation equation.
I can calculate the pH, pOH, [H3O+] and [OH-] based on given information of a acid-base reaction.

12. Acidic Solutions vs Basic Solutions
Acidic solutions will have an abundance of hydronium ions
[H3O+] = [H+]
Basic solutions will have an abundance of hydroxide ions
[OH-]

13. Acid Dissociation Acid Proton Conjugate base
HA  H A-
Acid Proton Conjugate
base
Alternately, H+ may be written in its hydrated form, H3O+ (hydronium ion)

14. Strong Acids to know
AP College Board would like you to know the following strong acids:
HCl, HBr, HI, HClO4 , H2SO4 , HNO3

15. Strong Bases Strong bases are metallic hydroxides
Group I hydroxides (NaOH, KOH) are very soluble
Group II hydroxides (Ca, Ba, Mg, Sr) are less soluble

16. Base Conjugate Hydroxide Acid
Dissociation of Bases
B + H2O  BH+ + OH-
Base Conjugate Hydroxide
Acid

17. pH Scale
The pH scale is a log based scale used to measure the acidity of a solution.
Smaller pH values are more acidic.
Bigger pH values are more basic.
pH levels at or very near 7 are considered to be neutral.

18. pH Calculations pH = -log[H+] pOH = -log[OH-] 14 = pH + pOH
10-pH = [H+]

19. pH and pOH Calculations

20. Relationship: OH- vs. H3O+
We can use the auto-ionization of water to determine the relationship between hydroxide and hydronium.
Kw is a constant at 25 C:
Kw = [H3O+][OH-]
Kw = (1 x 10-7)(1 x 10-7) = 1 x 10-14

21. Vamos a empezar…
What is the pH of a solution with a hydroxide concentration of 2.35 x 10-6M?
pOH = 5.63
pH = 8.37
What is the concentration of hydronium in this solution?
[H3O+] = 4.26 x 10-9 M