1. Acids and Bases Day 2 1

2. A beaker of aqueous solution has a pH of 7. 2 and the desired pH is 9
A beaker of aqueous solution has a pH of 7.2 and the desired pH is 9.4. Should an acid or base be added? 2

3. A beaker of aqueous solution has a pH of 7. 2 and the desired pH is 9
A beaker of aqueous solution has a pH of 7.2 and the desired pH is 9.4. Should an acid or base be added? Base, because to increase the pH, the H+ needs to be at a lower concentration. Bases will either increase the OH- levels or directly accept the Hydrogen ions 3

4. Arrhenius Acids and Bases
Producers
Acids produce H+
Bases produce OH-
Acids increase H3O+ concentration
Bases increase OH- concentration 4

5. Brønsted-Lowry Hydrogen Donor or Hydrogen acceptor
Acids donate Hydrogen Ions
Bases accept Hydrogen Ions 5

6. Brønsted-Lowry cont. Conjugate Acids and Base
When a base accepts a Hydrogen Ion/Proton from an acid, it becomes a conjugate base
When an acid donates a Hydrogen Ion/Proton to a base, it becomes a conjugate acid 6

7. Dissociation/Ionization
Acids and Bases break off their ions
Acid example: HCl + H2O H3O+ + Cl-
Base example: NaOH  Na+ + OH-
Acids will only dissociate in a solution
Bases can dissociate without another reactant, but it is rare 7

8. General formulas pH + pOH = 14 14 – pH = pOH 14 – pOH = pH
pOH = -log(OH-)
H+ = 10^(-pH)
pH = -log(H+) 8

9. Ka and pKa
The strength of an acid or base is determined by how easily it dissociates/ionizes
The easier it is for the substance to dissociate the stronger it is
Ka = [H3O+][A-] / [HA]
pKa = -log10(Ka)
Calculations with these concepts will be minimal
Higher pKa means more basic
Lower pKa (even going into the negatives) means more acidity 9

10. Concentration/dilution vs strength
Concentration is density and NOT strength
You determine concentration by how much of an acid or base is in the solution
Strength is determined by how easily ionized a substance is
A strong acid that is diluted can have a higher pH (less acidic) than a weak acid that is concentrated 10

11. Molarity (M) Measures concentration levels
Applies for both Acids and Bases
Moles / Liters
c = n/V 11

12. Which of the following substances is an Arrhenius Base?
A) CsOH
B) H2SO4
C) HI
D) HClO4 12

13. All Arrhenius Bases have “OH” in the molecular formula
All Arrhenius Bases have “OH” in the molecular formula. This is because they are defined by increasing the OH- concentration
A) CsOH 13

14. Which of the following substances is an Arrhenius Base?
A) HBr
B) NaClO-
C) HSO3
D) KOH 14

15. All Arrhenius Bases have “OH” in the molecular formula
All Arrhenius Bases have “OH” in the molecular formula. This is because they are defined by increasing the OH- concentration. Additionally, B) NaClO- is incorrect because it does not have a hydroxide (OH) although it is a strong base with a powerful negative charge.
D) KOH is the answer. 15

16. How would HNO3 dissociate in water?16

17. How would HNO3 dissociate in water?
First, note that the Hydrogen is written on the left side of the formula. This likely indicates that the substance is an acid.
Next, use your reference sheet and memory to confirm that NO3 is a polyatomic ion. This means that it will likely break off during ionization and leaving the Hydrogen alone.
Thus, the substance is an acid and will dissociate in the following manner:
HNO3 + H2O  H3O+ + NO3- 17

18. Write and balance the reaction for the following acid-base reactions AND label the acid, base, and salt in each:
HNO2 + Ca(OH) 2  18

19. HNO2 + Ca(OH) 2 
First, understand which is the acid and base. Acids normally have the Hydrogens on the left/front. Bases have their hydrogens on the right/back or don’t have them at all.
HNO2 (Acid) + Ca(OH)2 (Base) 
The Hydrogen and Hydroxide will combine to make water and the Ca and NO2 will combine to make the salt
Ca(NO2)2 (Salt) + H2O
HNO2 (Acid) + Ca(OH)2 (Base) Ca(NO2)2 (Salt) + H2O
Then it needs to be balanced.
2 HNO2 (Acid) + Ca(OH)2 (Base) Ca(NO2)2 (Salt) + 2H2O 19

20. What is the H+ concentration if the pH is 4.2?
A) 1.66E-4
B) 6.31E-5
C) 1.58E4
D) 3.16E5 20

21. Recall the general formulas
Recall the general formulas. If the pH is given, finding the H+ concentration requires you use: H+=10^(-pH) H+=10^(-4.2) =
B) 6.31E-5 21

22. What is the pH if the OH- concentration is 3.16E-9?
A) 8.5 pH
B) 7.5 pH
C) 6.5 pH
D) 5.5 pH 22

23. First, take the OH- concentration and find the pOH
First, take the OH- concentration and find the pOH. pOH=-log(OH-) pOH=-log(3.16E-9) pOH=8.5 Then, the pH can be found because the general formulas state that 14=pH+pOH 14-pOH=pH =5.5
D) 5.5 pH 23

24. What is the pOH if the p concentration is 6.3E-6?
A) 5.2 pH
B) 4.2 pH
C) 9.8 pH
D) 8.8 pH 24

25. First, take the H+ concentration and find the pH. pH=-log(H+) pH=-log(6.3E-6) pH=5.2 Then, the pOH can be found because the general formulas state that 14=pH+pOH 14-pH=pOH =8.8
D) 8.8 pOH 25

26. What is the molarity if 5 moles of HCl is placed in 100 Liters of water?
A) 5 M
B) 0.5 M
C) 0.05 M
D) M 26

27. n/V = c moles divided by volume equals concentration 5 mol / 100 L = 0
n/V = c moles divided by volume equals concentration 5 mol / 100 L = 0.05 M
C) 0.05 M 27