1. Acid/Base Definitions pH and pOH calculations

2. Evaluation/Assessment:
Objective:
Today I will be able to:
Define acid and bases based on the Arrhenius and Bronsted-Lowry definitions
Calculate the pH and the pOH for a compound
Evaluation/Assessment:
Informal assessment – listening to student responses to questions. Listening to group interactions as the students complete the practice problems
Formal assessment – analyzing student responses to the pH practice and the naming acids activity
Common Core Connection
Build Strong Content Knowledge
Make sense of problem and persevere in solving them
Reason abstractly and quantitatively
Construct viable arguments and critique the reasoning of others

3. Lesson Sequence Evaluate: Warm-Up Evaluate: Review HW
Explain: Acids and Bases Notes
Elaborate: Conjugate Acid/Base Practice
Explain: pH, pOH
Elaborate: pH Scale Practice
Evaluate: Exit Ticket

4. Warm - Up
Name the following acids and bases
HBr
H2SO4
NaOH
H2CO3
NH3

5. Objective Today I will be able to:
Define acid and bases based on the Arrhenius and Bronsted-Lowry definitions
Calculate the pH and the pOH for a compound

6. Homework
Finish the pH, pOH practice

7. Agenda Warm-Up Acids and Bases Notes Conjugate Acid/ Base Practice
pH, pOH notes
pH Scale Practice
Exit Ticket

8. ACID/BASE DEFINITIONS

9. 3 ways to define acids and bases
Arrhenius Theory
Bronstead-Lowry Theory
Lewis Theory – we will come back to the Lewis Definition later

10. What is an acid? Arrhenius Theory (Definition 1)
Substance that when dissolved in water, will yield H+ ions
Example
HCl(aq)  H+(aq) + Cl-(aq)

11. What is an acid? Bronsted-Lowry Theory (Definition 2)
An acid is a substance that can donate a proton
Example:
HCl(aq) + H2O(l)  H3O+(aq) + Cl-(aq)
H3O+ = Hydronium ion

12. Strong Acids vs. Weak Acids
Ionize almost 100% in water (react to completion)
Do not ionize completely, achieve an equilibrium

13. Examples Strong Acids Weak Acids HCl – hydrochloric acid
HBr - hydrobromic acid
HI - hydroionic acid
H2SO4 – sulfuric acid
HNO3 - nitric acid
HClO3 – chloric acid
Weak Acids
HF – hydrofluoric acid
CH3COOH – acetic acid
HCN - hydrocyanic acid

14. What is a base? Arrhenius Theory (Definition 1)
Substance that yields hydroxide ions (OH-) as the only negative ions in an aqueous solution
Example
NaOH(s)  Na+(aq) + OH-(aq)

15. What is a base? Bronsted-Lowry (Definition 2)
Any substance that can combine with or accept a proton (H+)
Can be substances besides hydroxides
NH3(aq) + H2O(l)  NH4+(aq) + OH-(aq)

16. Strong vs. Weak Bases Ionize close to 100% Reach equilibrium Examples
NaOH - sodium hydroxide
KOH – potassium hydroxide
LiOH – lithium hydroxide
Reach equilibrium
Examples
Most bases that are not considered strong, NH3 (ammonia)

17. BRONSTEAD-LOWRY CONJUGATE ACID/BASE PRACTICE
You have 15 minutes to complete the practice problems

18. How can we measure the strength of an acid?

19. pH Scale
A one unit change in pH represents a ten fold change in the H3O+ concentration
pH = - log [H3O+]
Water that falls near a coal burning power plant has a [H3O+] = 6.23 x 10-4 M. What is the pH?
pH = 3.2 (acidic)

20. pH Scale You can also calculate [H3O+] when given a pH [H3O+] = 10-pH
Human blood has a pH of Calculate the [H3O+]
[H3O+] =
[H3O+] = 5.01 x 10-8 M

21. pH Scale Figuring out the pH of a base is a little different – use pOH
pH + pOH = 14
-log [OH] = pOH
What is the pH of a NaOH solution that has a [OH] of M?
-log [0.025] = 1.6 = pOH
= 12.4 = pH

22. Disclaimer Acid-Base strength is the not the same as concentration
Strength – the amount of ionization or breaking apart that a particular acid or base undergoes
Concentration – amount of acid or base that you initially have
You can have a concentrated solution of weak acid, or a dilute solution of a strong acid, or a concentrated solution of a strong acid, etc…

23. PH SCALE PRACTICE
Complete the practice at your desk. Problems not completed in class will become your homework

24. Exit Ticket
Name the following bases
NaOH
NH3
LiOH
KOH