2. OUTCOME QUESTION(S):
C ACID/BASE AND pH
Outline acid/base theories and write acid/base equations. Include: Arrhenius, Bronsted-Lowry, Lewis.
Distinguish between strong and weak acids and bases. Include: electrolytes and non-electrolytes
Formulate an operational definition of pH and solve problems.
Vocabulary & Concepts 
concentrated dilute indicator

3. Associated Thought:
Don't confuse weak and strong with dilute and concentrated:
Weak and strong indicates the proportion of an acid or base which ionized (balance at equilibrium)
Dilute and concentrated refer to the volume of acid and base dissolved (in a total solution)
It is possible to have a concentrated weak acid/base or a dilute strong acid/base

4. HA H+ + A- HA + H2O H3O+ + A- +x - x + x - x + x +x [I] [C] [E] [I]
Strong Acid HA
H A-
2.5 M
[I] +x
+ x
- x
[C]
2.5 M
[E]
The more dilute acid (↑) has a higher concentration of corrosive H+ ions because it dissociates 100%
Note the way the two equations show strong and weak with the arrows and inclusion of water
Weak Acid
HA + H2O
H3O A-
10 M
[I] +x
+ x
- x
[C]
9.0 M
1.0 M
[E]

5. H+ and H3O+ are interchangeable
Generally it can be stated:
Acidic: [H3O+] > [OH-]
Alkaline (basic): [OH-] > [H3O+]
Neutral: [OH-] = [H3O+]
Remember:
H+ and H3O+ are interchangeable
Soren Sorensen developed a simplified system for the degree of acidity of a solution: pH
POWER OF HYDROGEN
potenz of wasserstoff – German
puissance of hydrogène – French
potentia hydrogenii – Latin

6. Equation 1: pH = - log [H+] Equation 2: [H+] = 10-pH
These equations allow for the conversion between hydrogen ion concentration and a simple scale that all can understand
pH scale contains values between 0 – 14:
neutral – 7
more acidic
less acidic

7. pH = - log [H+] pH = -log[H+] = -log(0.1) = -(-1.0) = 1 Equation 1:
Notice each pH step of
1 unit is actually a 10x change in hydrogen ion concentration…
So an acid with pH of 1 is 100x stronger than an acid with pH of 3
pH = -log[H+]
= -log(0.1)
= -(-1.0)
= 1

8. Remember strong acids are 100% dissociating:
Calculate the pH of an HCl solution whose concentration is 5.0 x 10-6 mol/L.
Remember strong acids are 100% dissociating:
[HA]i = [H+]e
Equation 1:
pH = - log [H+]
= -log(5.0 x 10-6 M)
= -(-5.30)
= 5.30

9. Find the “10 x” button on your calculator
The pH of a solution is Calculate the hydrogen ion concentration in the solution.
Equation 2:
[H+] = 10-pH
Find the “10 x” button on your calculator =
= 5.6 x 10-4 M

10. Notice the two scales are inverse of each other
Basic properties (OH-) can also be measured with a separate scale – like pH:
Equation 3: pOH = - log [OH-]
Equation 4: [OH-] = 10-pOH
pOH scale contains values between 0 – 14:
neutral – 7
more basic
less basic
Notice the two scales are inverse of each other

11. pH + pOH = 14 pOH pH Equation 5:
Acidic solution will have a low pH and high pOH
Basic solution will have a low pOH and high pH
inverse scales total 14 for any solution
neutral
more basic
less basic
neutral
less acidic
more acidic
Equation 5:
pH + pOH = 14

12. pH/pOH Formulae pH Equation 5: [H+] pOH [OH-] pH = - log [H+]
pOH = - log [OH-]
pOH
[OH-]
Equation 4:
[OH-] = 10-pOH

13. Alkali earth metal hydroxide - strong base – 100% dissociates
What is the pH of 5.0 x 10-5 M Mg(OH)2 solution?
Alkali earth metal hydroxide - strong base – 100% dissociates pH
pOH
[OH-]
Mg(OH)2 (s) Mg2+(aq) + 2 OH-(aq)
[E] xi xe xe
[E]
[I]
[C]
- x
+ x
+ 2x x 2x
[OH-] = 2x = 2(5.0 x 10-5 M)
= 1.0 x 10-4 M
Equation 3: pOH = -log[OH-] = 4.00
Equation 5: pH = = 10.00

14. The pH of a solution is 10.30, what is the hydroxide ion concentration?
pOH
[OH-]
Equation 5: pOH = pH
pOH =
= 3.70
Equation 4: [OH-] = 10-pOH
[OH-] =
= 2.0 x 10-4 mol/L

15. Measuring pH There are two ways to measure pH: pH Meters Indicators
Probes must be calibrated
(set against a known pH)
Indicator: weak acid or base that undergoes a colour change with the gain or lose of H+.
Colour changes at various pH depending on indicator
Le Chatelier’s applies to the colour change

16. Hphph H+ + phph- HLit H+ + Lit - Phenolphthalein
Weak acid is colourless - conjugate base is bright pink
Weak Acid
Con Base
Hphph
H phph-
Think about how the presence of an acid or base would “shift” equilibrium for these reactions
2. Red Litmus
Mix of dyes that turn blue in presence of base.
Red
Blue
HLit
H Lit -

17. Some Natural pH indicators
Beets , Blackcurrant juice , Blueberries , Cherries , Grapes , Onion , Red cabbage , Rhubarb , Rose Petals , Turmeric

18. CAN YOU / HAVE YOU?
C ACID/BASE AND pH
Outline acid/base theories and write acid/base equations. Include: Arrhenius, Bronsted-Lowry, Lewis.
Distinguish between strong and weak acids and bases. Include: electrolytes and non-electrolytes
Formulate an operational definition of pH and solve problems.
Vocabulary & Concepts 
concentrated dilute indicator