1. Exam 2 Wednesday 4/4
Homework 9 posted and due Monday 4/2

2. Bronsted Model of Acids/Bases 3 new concepts (see pp 452-453 & 623-6)
CLASSICAL REACTIONs OVERVIEW(continued)
Bronsted Model of Acids/Bases 3 new concepts (see pp & 623-6)
New Concept #1: Follow the protons
Acid=
proton donor (=H+)
No real change from Arrhenius
HF, HCl, HBr
HNO3 HClO4
H2SO4 H2CO3
H3PO4
ARRHENIUS ACIDS = BRONSTED ACIDS

3. …nearly any negative ion (=anion) that even weakly attracts protons
CLASSICAL REACTIONs OVERVIEW(continued)
BRONSTED’S MODEL OF ACIDS/BASES: New Concept #1: following the protons (cont.)
BASE=
proton acceptor
Examples of Bronsted Bases
OH-
CO3-2 ,PO4-3, C2H3O2-,SiO3-2…
The set of Bronsted bases includes Arrhenius bases + ….
…nearly any negative ion (=anion) that even weakly attracts protons

4. Hydrolysis…Bronsted bases `split’ water !!!
CLASSICAL REACTIONs OVERVIEW(continued)
BRONSTED’S MODEL OF ACIDS/BASES: New Concept #2
How the proton acceptor creates the basic salt effect:
Hydrolysis…Bronsted bases `split’ water !!!
EXAMPLE
CO32- + H-OH
 HCO OH-
Hydrolysis reaction
..Bronsted Base is basic in water because it splits water to make OH- !

5. Identify `acids’ and bases
BRONSTED’S MODEL OF ACIDS/BASES: New Concept #3a: conjugate acid/base pairs
Conjugate idea is like going drag…
Men=acid Women=base
Identify `acids’ and bases
CONJUGATE
ACID
CONJUGATE
BASE
BASE
ACID

6. Identify `acid’ and base Identify conjugate acid and base
CLASSICAL REACTIONs OVERVIEW(continued)
BRONSTED’S MODEL OF ACIDS/BASES: New Concept #3a: conjugate acid/base pairs
Identify `acid’ and base
Identify conjugate acid and base
Conjugate acid
 HCO OH-
CO32- + H-OH
Acid
Base
Conjugate base
Acid conjugate base
Base conjugate acid

7. new concept #3a: Conjugates (continued)
When acid and base reacts….
Acid conjugate base
Base conjugate acid
EXAMPLE: IDENTIFY ACID, BASE AND THEIR CONJUGATE BASE AND ACID ABOVE
PO43- + HCO3 -  HPO42- + CO32-
CONJUGATE
ACID
CONJUGATE BASE
BASE
ACID

8. Bronsted Model Contrast to Arrhenius Model
CLASSICAL REACTIONs OVERVIEW(continued)
BRONSTED’S MODEL OF ACIDS/BASES: New Concept #3b:
Bronsted Model
ACID + BASE CONJUGATE BASE + CONJUGATE ACID
spontaneous acid + base reactions
produce weaker acids + bases
Contrast to Arrhenius Model
ACID + BASE SALT WATER
Both products `neutral’

9. ACID-BASE THEORIES SUMMARIZED
ARRHENIUS
BRONSTED
PROTON DONOR
ACID =
H+ DONOR
BASE=
OH- DONOR
PROTON DONOR
ACID + BASE 
SALT +
WATER
CONJUGATE ACID + CONJUGATE BASE

10. What observation required Bronsted to create a new Acid/Base Theory different than Arrhenius’s model ?
Many salts formed conjugate acids.
Spontaneous acid+base reactions only occurred if weaker acids and bases formed.
H2O spontaneously decomposed to OH- and H+ in presence of various salts.
Many salts without OH- somehow created OH- in water.

11. Which part of the Bronsted salt K3PO4 is the proton acceptor ?
OH-

12. What new concept of Bronsted’s most directly explains why many salts are bases?
The anionic part of salts can hydrolyze water.
Spontaneous acid/base reactions lead to weaker conjugate acids/bases.
Bronsted bases are proton acceptors.
Bronsted acids are proton donors.

13. In-class reaction Jeopardy
WHAT IS…
Low heat, precipitates, cation swap
metathesis
Pick the Arrhenius acids
H2O HNO3 NaHCO3 HBr NaCl
HNO3 HBr
Na2CO3 for example
A Bronsted base
What’s my reaction type:
Acid/base neutralization (Arrhenius)
HCl + KOH KCl + H2O

14. In-class reaction Jeopardy
WHAT IS…
What’s my reaction type:
Acid/base hydrolysis
(Bronsted)
K3PO4 + H2O  HK2PO4 + KOH
Write my products ?
AgNO3(aq) + NaCl(aq) ?
AgCl(s) + NaNO3(aq)
Pick the Bronsted base(s)
NaOH NaHCO3 K3PO4
Pick the Arrhenius bases
NaOH
NaOH HBr NaHCO3 K3PO4

15. Still want more
practice with
Acid/Base and Metatheses ????

16. OXIDATION-REDUCTION (REDOX) REACTIONS
REDOX REACTIONS ALL INVOLVE CHANGES IN ELECTRON OWNERSHIP
EXAMPLE #1: (w/demo) +1
Mgo + 2H+  Mg2+ + H2 +2
Mg loses 2 e-
Losing is oxidation
Each H+ gains 1 e-
Gaining is reduction

17. Lose electrons = oxidation Gain electrons =reduction
Oxidation-Reduction:
Remembering which is which…..
Leo-Ger
Lose electrons = oxidation
Gain electrons =reduction

18. Oil-Rig Oxidation is losing Reduction is gaining Oxidation-Reduction:
Remembering which is which…..
Oil-Rig
Oxidation is losing
Reduction is gaining

19. Qualitative Features of REDOX Reactions
Often involves gross changes in state
(solid gas or solution)
Extreme changes in energy
(fire, light, explosions)
prime engine of living metabolisms
(if you breathe, you redox…)

20. To emphasize, metals often written Mo
How to know if a reaction is a `redox’ reaction:
assign OXIDATION NUMBERS
1) PURE UNCHARGED ELEMENTS HAVE 0 OXIDATION #
H2 O2 N2 Fe Cu Au
To emphasize, metals often written Mo
Example: Fe  Feo

21. F- Co3+ H+ S2- How to know if a reaction is a `redox’ reaction:
assign OXIDATION NUMBERS
THE RULES: (continued)
2) OXIDATION # OF A CHARGED ATOM IS THE CHARGE ITSELF -1 +3 +1 -2
F Co H+ S2-

22. How to know if a reaction is a `redox’ reaction:
assign OXIDATION NUMBERS
THE RULES: (continued)
3) F (AND USUALLY THE OTHER HALOGENS) ARE -1 in binary and larger compounds
* *
NaF HCl NCl SiOF2
* Each atom of Cl or F is -1

23. How to know if a reaction is a `redox’ reaction:
assign OXIDATION NUMBERS
THE RULES: (continued)
4) O IS -2 EXCEPT IN PEROXIDES (X-OO-Y) WHERE IT IS -1
* *
H2O NaOH K2CrO4 NaMnO4
* Each atom of O in compound is -2
-1 -1
PEROXIDE STRUCTURE
HOOH =H2O2

24. How to know if a reaction is a `redox’ reaction:
assign OXIDATION NUMBERS
THE RULES: (continued)
5) H IS +1 FOR COVALENT COMPOUNDS (AND MOST IONIC ONES TOO)
* +1* *
HCl NH3 H2O CH4
*Each H in the compound is +1

25. Oxidation # RULES SUMMARIZED
1) PURE UNCHARGED ELEMENTS HAVE 0 OXIDATION #
2) OXIDATION # OF A CHARGED ATOM IS THE CHARGE ITSELF
F (AND USUALLY THE OTHER HALOGENS) ARE
-1 IN BINARY AND LARGER COMPOUNDS
4) O IS -2 EXCEPT IN PEROXIDES (X-OO-Y) WHERE IT IS -1
5) H IS +1 FOR COVALENT COMPOUNDS (AND MOST IONIC ONES TOO)

26. N2 O2 H2O Fe2O3 H2SO4 N=0 O=0 H=+1 O= -2 Fe=+3 O= -2 H= +1 O= -2 S=+6
PRACTICE ASSIGNING OXIDATION #
Provide oxidation # for all elements below N2 O2
H2O
Fe2O3
H2SO4
N=0
O=0
H=+1 O= -2
Fe=+3 O= -2
H= +1 O= -2 S=+6

27. Zn(s) + 2HCl(aq)  ZnCl2(aq) + H2(g)
PRACTICE ASSIGNING OXIDATION #(cont.)
Zn(s) + 2HCl(aq)  ZnCl2(aq) + H2(g) Zn
Which element oxidized ?
w/demo
Which element reduced ? H
2Al(s) + 3CuSO4(aq) Al2(SO4)3(aq) + 3 Cu(s)
Which element oxidized ? Al
w/demo
Which element reduced ? Cu

28. What are the oxidation # for H, Mn and O in HMnO4

29. What is oxidized and reduced in the reaction: PbO + COPb+CO2
O reduced, Pb oxidized
C reduced, Pb oxidized
Pb reduced, O oxidized
Pb reduced, C oxidized

30. In the reaction: CH4+2O2 CO2+2H2O the oxidation # for reactant C vs
In the reaction: CH4+2O2 CO2+2H2O the oxidation # for reactant C vs. product C and reactant O vs. product O are:
C ; O
+4 vs. -4; 0 vs. +2
0 vs. +4; -2 vs. +2
-4 vs. +4; 0 vs. +2
-4 vs.+4; 0 vs. -2

31. What is oxidized and reduced in the reaction: CH4 +2O2CO2 +2H2O
C oxidized, O reduced
H oxidized, C reduced
C oxidized, H reduced
O oxidized. C reduced