1. Unless otherwise stated, all images in this file have been reproduced from:
Blackman, Bottle, Schmid, Mocerino and Wille,      Chemistry, 2007 (John Wiley)      ISBN:

2. A/Prof Adam Bridgeman (Series 1) Dr Feike Dijkstra (Series 2)
CHEM1002 [Part 2]
A/Prof Adam Bridgeman (Series 1)
Dr Feike Dijkstra (Series 2)
Weeks 8 – 13
Office Hours: Monday 2-3, Friday 1-2
Room: 543a
It is a good idea if all lecturers can make an appearance for the first lecture.
Remind students we are IT for the rest of the semester.
DEMOS for this lecture:
EXP 2.3: “Charles law (2.3),
EXP 2.1 “CO2 density (2.1)

3. Acids and Bases Lecture 1: Common Acids and Bases Definitions
Equilibria
Conjugate acid-base pairs
Autoionisation of water pH
Blackman Chapter 11, Sections
Reproduced from ‘The Extraordinary Chemistry of Ordinary Things, C.H. Snyder, Wiley, 2002 (Page 245)

4. Use of Common Acids and Bases
Substance Formula Use
Acids
Acetic acid CH3COOH flavouring; preservative
Citric acid C6H8O7 flavouring
Phosphoric acid H3PO4 rust remover
Boric acid B(OH)3 mild antiseptic; insecticide
Hydrochloric acid HCl brick/ceramic tile cleaner
Bases
Sodium hydroxide NaOH oven cleaner
Ammonia NH3 household cleaner
Sodium carbonate Na2CO3 water softener; grease remover
Sodium hydrogen NaHCO3 fire extinguisher; baking powder carbonate
Reproduced from ‘The Extraordinary Chemistry of Ordinary Things, C.H. Snyder, Wiley, 2002 (Page 231)

5. Definitions Arrhenius: H+(aq) + OH-(aq) H2O(l)
ACID: H+ producer in aqueous solution e.g. HCl
BASE: OH- producer e.g. NaOH
Brønsted - Lowry: H+ + A HA
ACID: proton donor (H+) e.g. HCl
BASE: proton acceptor e.g. NH3

6. HA(aq) + H2O(l) H3O+(aq) + A-(aq)
Acids, Bases & Equilibrium
HA(aq) + H2O(l) H3O+(aq) + A-(aq)
A STRONG acid has equilibrium to the right (HA completely ionised)
A WEAK acid has equilibrium to the left (HA partly/mostly intact)
Equilibrium Equation:
Ka is the ACID DISSOCIATION CONSTANT

7. Conjugate Acid-Base Pairs
NH4+ is the conjugate acid of NH3
NH3 is the conjugate base of NH4+
A conjugate base has one less proton than its conjugate acid
HSO4–: conjugate base is SO42– conjugate acid is H2SO4
H2SO4 is a dibasic or diprotic acid:
H2SO4(aq) + H2O(l) H3O+(aq) + HSO4–(aq)
HSO4–(aq) + H2O(l) H3O+(aq) + SO42–(aq)

8. Acid-Base Reactions ACID + BASE BASE + ACID HF(aq) + H2O(l)
conjugate pair
ACID BASE
BASE ACID
conjugate pair
HF(aq) H2O(l)
HCOOH(aq) CN-(aq)
H2PO4-(aq) OH-(aq)
NH4+(aq) CO32-(aq)
F-(aq) H3O+(aq)
HCOO-(aq) HCN(aq)
HPO42-(aq) H2O(l)
NH3(aq) HCO3-(aq)

9. Autoionisation of Water
2 H2O(l) H3O+(aq) + OH–(aq)
Equilibrium constant given special symbol:
Kw = [H3O+][OH– ] NB: [H2O(l)] = constant
At 25 °C: Kw = 1.0  10-14
Neutral solution: [H+] = [OH– ] = 1.0  10-7 M
Acidic solution: [H+] > 1.0  10-7 M
Basic: [H+] < 1.0  10-7 M
remember this

10. pH = -log10[H+] pOH = -log10[OH-] pH + pOH = 14 The pH Scale
Because the concentrations of acids and bases can vary over many orders of magnitude, it is convenient to define a logarithmic scale to compare them:
pH = -log10[H+]
pOH = -log10[OH-]
pH + pOH = 14
e.g. If [H+] = 1.0 x 10-6 M then pH = -log(10-6) = - (-6) = 6.00
Hence, pOH = – 6.00 = 8.00 and [OH-] =

11. The ‘p’ Convention pH = – log10[H+] pOH = – log10[OH– ]
pKw = – log10Kw = at 25 °C
Acid : pH < 7
Neutral: pH = 7
Basic: pH > 7
Since Kw = [H+][OH– ]:
log10 Kw = log10 [H+] + log10 [OH– ]
– log10 [H+] – log10 [OH– ] = – log10 Kw
pH + pOH = 14
pOH = 14 – pH

12. Temperature Dependence of pH
H2O
H+ + OH-
ΔH0 = 56 kJ mol-1 Ea
Kw = 1.0  only at 25 °C
Reaction is endothermic: it is more favourable at higher temperature
For T > 25 °C, Kw > 10-14
For T < 25 °C, Kw < 10-14
 pH + pOH  14 if T  25 °C
 neutral pH  7 if T  25 °C !

13. } [H+] ACIDIC NEUTRAL BASIC pH 1 M NaOH Household Ammonia Sea Water
10-14
10-12
10-10
10-8
10-6
10-4
10-2
100
ACIDIC
NEUTRAL
BASIC pH 14 12 10 8 6 4 2
1 M NaOH
Household Ammonia
Sea Water }
Blood
Pure Water
Milk
Vinegar
Lemon Juice
Stomach Acid
1 M HCl

14. Practice Examples
1. Calculate the pH for solutions with each of the [H+(aq)] concentrations below
(a) 10.0 M
(b) 1.00 M
(c) 0.10 M
(d) M
2. Calculate the pH for solutions with each of the [OH-(aq)] concentrations below

15. Summary: Acids & Bases 1 List common acids and bases
Learning Outcomes - you should now be able to:
Complete the worksheet
List common acids and bases
Define acids & bases
Use pH and Kw
Answer Review Problems and in Blackman
Next lecture:
Calculations involving acids and bases