1. Stay Strong or Be Neutral
ACIDS & BASES
Stay Strong or Be Neutral

2. Acids and Bases Arrhenius Model (1884) Bronsted-Lowery Model (1923)
Acid produces excess H+ in water
Base produces excess OH-
Very practical, but one disadvantage. It restricts the number of reactions that can be considered acid/base
Bronsted-Lowery Model (1923)
Acid is H+ donor
Base is H+ acceptor

3. Strong Acids and Bases Strong Acids Strong Bases HCl (aq) HBr (aq)
HI (aq)
HNO3 (aq)
HClO4 (aq)
H2SO4 (aq)
Strong Bases
LiOH
NaOH
KOH
Ca(OH)2
Sr(OH)2
Ba(OH)2

4. Strong: Ionize 100% pH = -log[H3O+ ] Strong acid HA +H2O H3O+ + A-
[Acid] = [H3O+ ]
pH = -log[H3O+ ]
Base must be soluble hydroxide
BOH  B+ + OH-
[Base] = [OH-]
pOH = -log [OH-]

5. Weak: Don’t ionize 100% Bronsted-Lowry model for Acid-Base Reactions
HA + H2O D H3O+ + A-
HA acid and A- conjugate base
B + H2O D BH+ + OH-
B base and BH+ conjugate acid

6. Conjugate Acid/Base Conjugate Acid Conjugate Base HF F- HSO4- SO42-
NH4+
NH3

7. In this unit we are only going to be dealing with STRONG ACIDS/BASES.

8. Determining Acid or Base
We determine if a substance is an acid or base based on its pH.
In lab we use…
pH meter
Indicators
Phenolphthalein pH of 9
Methyl Red pH of 5
Bromthymol blue pH of 7
pH strips

9. Review pH pH less than 7 is acidic pH equal to 7 is neutral
pH greater than 7 is basic
Remember pH is based on a power of 10
The smaller the pH the stronger the acid
The larger the pH the stronger the base

10. The Ion product of water
Because of the water decomposes, it has a Kw constant of 1.0 E-14
Kw stands for equilibrium of water constant

11. Formulas pH + pOH= 14 pH = -log[H+] pOH = -log[OH-]
[H+] * [OH-] = 1 x 10-14

12. Find the pH and pOH with the following [H+]
1.0 M
1.7 E-4 M
6.8 E-8 M

13. Calculate the [H+] and [OH-] in solutions with the following pH.
4.0
8.52
0.00
12.60

14. Solution X has pH 11. 7. Solution Y has [OH-]= 4. 5 E-2
Solution X has pH Solution Y has [OH-]= 4.5 E-2. Which solution is more basic? Which has a higher pH?

15. Milk of magnesia has a pH of 10. 5
Milk of magnesia has a pH of Calculate the concentration of the hydrogen ion. Calculate the ratio of the hydrogen ions concentration of gastric juice, pH 1.5, to that of milk of magnesia.

16. Homework 1: Page 374 (7-15 odd)

17. We can also find the pH of a solution based on the [H+] and [OH-]
Find the [H+] and pH of the following solutions.
1.75 L of a 37.5% (by mass) solution (d=1.0g/mL) of HCL. What is the pH of L of the same solution?
A solution made up of 22g of HBr dissolved in enough water to make 479 mL of solution. What is the pH if the same mass of HBr is dissolved in enough water to make 47.9 mL of solution?

18. Find pH
What is the pH of a solution obtained by adding 145 mL of M HCl to 493 mL of a HNO3 solution with a pH of Assume the volumes are additive.

19. Find [OH-], [H+], pH & pOH
45.0 mL of M Ba(OH)2 diluted with enough water to make 350 mL of solution.
A solution made by dissolving 4.68 g of NaOH in enough water to make 635 mL of solution.

20. Homework 2: odd

21. Acid/Base Titrations Strong acids/bases ionize completely in water.
The neutralization reactions that takes place when any strong acid reacts with any strong base can be represented by a net ionic equation.
**Write the equations on the board.

22. Acid/Base Titrations
The K of the formation of water through acid/base neutralization is 1.0 E14. Such an enormous K value means that for all practical purposes this reaction geos to completion.
Titrations are based on stoichiometric factors
At the equivalence point, the pH is 7
Near the equivalence point, the pH varies greatly.

23. Acid/Base titrations
When mL of 1.0 M HCl is titrated with 1.0 M of NaOH, the pH increases.
Find the initial pH
Find the pH after mL NaOH has been added.
Find the pH after mL of NaOH has been added.
Find out how much NaOH is needed to reach the equivalence point.
Based on the pH’s found above, what indicators can be used to in this acid base reaction.
Find the pH ½ way to the equivalence point.
Find the pH 5 mL past the equivalence point.

24. Homework 3: page & 44