e3 redox: transferring electrons - university of michiganchem125/f08/lec05e3f08key.pdf · two hours...
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Chem. 125-126: Oct. 1 - Oct. 7
Agenda One hour discussion of E2(Questions, p.73) Two hours of E3; E3= two session 5 hour lab
Preparation Pre-lab Report (p.90) for E3 completed Discussion Presentation for E2 completed Pre-lab reading and studies for E3 completed
E3: Redox: Transferring Electrons
Session 1: Two Hour Lab Agenda* Complete Part 1 Complete Part 2A Complete Team Report (Parts 1 and 2A) * See Student Information Sheet on Ctools underResources → Experiments.
Session 2: Three Hour Lab Agenda Complete Parts 2B and 3
E3 Redox: Transferring Electrons
Redox = oxidation-reduction
Redox reactions involve electron transfer.
Loss of electrons (LEO) = oxidation Gain of electrons (GER) = reduction
1A VIIIA1H1s1 IIA IIIA IVA VA VIA VIIA
2He1s2
3Li2s1
4Be2s2
5B
2s22p1
6C
2s22p2
7N
2s22p3
8O
2s22p4
9F
2s22p5
1 0Ne
2s22p6
1 1Na3s1
1 2Mg3s2 IIIB IVB VB VIB VIIBVIIIB ⇔VIIIB IB IIB
1 3Al
3s23p1
1 4Si
3s23p2
1 5P
3s23p3
1 6S
3s23p4
1 7Cl
3s23p5
1 8Ar
3s23p6
1 9K4s1
2 0Ca4s2
2 1Sc
3d14s2
2 2Ti
3d24s2
2 3V
3d34s2
2 4Cr
3d54s1
2 5Mn
3d54s2
2 6Fe
3d64s2
2 7Co
3d74s2
2 8Ni
3d84s2
2 9Cu
3d1 04s1
3 0Zn
3d1 04s2
3 1Ga
4s24p1
3 2Ge
4s24p2
3 3As
4s24p3
3 4Se
4s24p4
3 5Br
4s24p5
3 6Kr
4s24p6
3 7Rb5s1
3 8Sr5s2
3 9Y
4d15s2
4 0Zr
4d25s2
4 1Nb
4d35s2
4 2Mo
4d55s1
4 3Tc
4d55s2
4 4Ru
4d75s1
4 5Rh
4d85s1
4 6Pd
4d10
4 7Ag
4d1 05s1
4 8Cd
4d1 05s2
4 9In
5s25p1
5 0Sn
5s25p2
5 1Sb
5s25p3
5 2Te
5s25p4
5 3I
5s25p5
5 4Xe
5s25p6
5 5Cs6s1
5 6Ba6s2
5 7La*
5d16s2
7 2Hf
5d26s2
7 3Ta
5d36s2
7 4W
5d46s2
7 5Re
5d56s2
7 6Os
5d66s2
7 7Ir
5d76s2
7 8Pt
5d96s1
7 9Au
5d1 06s1
8 0Hg
5d1 06s2
8 1Tl
6s26p1
8 2Pb
6s26p2
8 3Bi
6s26p3
8 4Po
6s26p4
8 5At
6s26p5
8 6Rn
6s26p6
8 7Fr7s1
8 8Ra7s2
8 9Ac#
6d17s2
1 0 4 +
6d27s2
1 0 5 +6d37s2
1 0 6 +6d47s2
1 0 7 +6d57s2
1 0 8 +6d67s2
1 0 9 +6d77s2
+ Element synthesized,but no official name assigned
Background Information: Redox
Metals lose electrons Non-metals gain electrons (LEO) GER)
+ 1 1 1A
+3
+4
+5
+6
18 VIIIA
1 H 1s1
+2 2 IIA
+1 13 IIIA
+2 14 IVA
+3 15 VA
+4 16 VIA
17 V I I A
3 Li 2s1
4 Be 2s2
1 1 Na 3s1
1 2 Mg 3s2
3
IIIB
4
IVB
5 VB
6
VIB
7
VIIB
8 VI I IB
9 ⇔
10 VIIIB
11 IB
12 IIB
1 3 Al
3s23p1
1 9 K 4s1
2 0 Ca 4s2
2 1 Sc
4s23d1
2 2 Ti
4s23d2
2 3 V
4s23d3
2 4 Cr
4s13d5
2 5 Mn
4s23d5
2 6 Fe
4s23d6
2 7 Co
4s23d7
2 8 Ni
4s23d8
2 9 Cu
4s13d10
3 0 Zn
4s23d10
3 1 Ga
4s24p1
3 2 Ge
4s24p2
3 7 Rb 5s1
3 8 Sr 5s2
3 9 Y
5s24d12
4 0 Zr
5s24d2
4 1 Nb
5s24d3
4 2 Mo
5s14d5
4 3 Tc
5s23d5
4 4 Ru
5s14d7
4 5 Rh
5s14d8
4 6 Pd
4d10
4 7 Ag
5s14d10
4 8 Cd
5s24d10
4 9 In
5s25p1
5 0 Sn
5s25p2
5 1 Sb
5s25p3
5 5 Cs 6s1
5 6 Ba 6s2
5 7 L a *
6s25d1
7 2 Hf
6s25d2
7 3 Ta
6s25d3
74 W
6s25d4
7 5 Re
6s24d5
7 6 Os
6s25d6
7 7 Ir
5d76s2
7 8 Pt
6s15d9
7 9 Au
6s15d10
8 0 Hg
6s25d10
8 1 Tl
6s26p1
8 2 Pb
6s26p2
83 Bi
6s26p3
8 4 Po
6s26p4
8 7 Fr 7s1
8 8 Ra 7s2
8 9 Ac#
7s26d1
1 0 4 +
7s26d2
1 0 5 + 7s27d3
1 0 6 + 7s26d4
1 0 7 + 7s23d5
1 0 8 + 6s26d6
109 + 6d77s2
+ Element synthesized, but no official name assigned
Q. Max positive oxidation state of family A metal ions?
Sn = 0 or 2+ or 4+
Q. Oxidation states ofSn?
11A
18VIIIA
1H1s1
2IIA
13IIIA
14IVA
15VA
16VIA
17VIIA
3Li2s1
4Be2s2 +2
↓ +2 ↓
+2 ↓
+2 ↓
+2 ↓
1 1Na3s1
1 2Mg3s2
+3 3 IIIB
+ 4 4
IVB
+ 5 5 VB
+6 6
VIB
+7 7
VIIB 8VIIIB
+2 9 ⇔
10 VIIIB
+1 11 IB
+2 12 IIB
1 3Al
3s23p1
1 9K4s1
2 0Ca4s2
2 1Sc
4s23d1
2 2Ti
4s23d2
2 3V
4s23d3
2 4Cr
4s13d5
2 5Mn
4s23d5
2 6Fe
4s23d6
2 7Co
4s23d7
2 8Ni
4s23d8
2 9Cu
4s13d10
3 0Zn
4s23d10
3 1Ga
4s24p1
3 2Ge
4s24p2
3 7Rb5s1
3 8Sr5s2
3 9Y
5s24d12
4 0Zr
5s24d2
4 1Nb
5s24d3
4 2Mo
5s14d5
4 3Tc
5s23d5
4 4Ru
5s14d7
4 5Rh
5s14d8
4 6Pd
4d10
4 7Ag
5s14d10
4 8Cd
5s24d10
4 9In
5s25p1
5 0Sn
5s25p2
5 1Sb
5s25p3
5 5Cs6s1
5 6Ba6s2
5 7La*
6s25d1
7 2Hf
6s25d2
7 3Ta
6s25d3
7 4W
6s25d4
7 5Re
6s24d5
7 6Os
6s25d6
7 7Ir
5d76s2
7 8Pt
6s15d9
7 9Au
6s15d10
8 0Hg
6s25d10
8 1Tl
6s26p1
8 2Pb
6s26p2
8 3Bi
6s26p3
8 4Po
6s26p4
8 7Fr7s1
8 8Ra7s2
8 9Ac#
7s26d1
1 0 4 +
7s26d2
1 0 5 +7s27d3
1 0 6 +7s26d4
1 0 7 +7s23d5
1 0 8 +6s26d6
1 0 9 +6d77s2
+ Element synthesized,but no official name assigned
Transition Metals Q. Maximum oxidation state vs. family # ? Redox Reactions
Example of Metal and Non-Metal Reaction: 2 Na + Cl2 → 2 NaCl + energy
DEMO
LEO GER
Redox Reactions
2 Na(s) + Cl2 (g) → 2 NaCl(s)
Reactants transfer electrons.
Reactants change charge (oxidation state).
Gain of e’s = reduction (Cl → Cl - in NaCl)
Lose of e’s = oxidation(Na → Na + in NaCl) 2 Na + Cl2 → 2 Na+ + 2 Cl-
Oxidation Reduction
2 ( ) ( )( > in oxidation state) ( < in oxidation state)
Na → Na+ + e- Cl2 + 2e- → 2Cl-
Half rxns always written to show electron GAIN.
The equation = the sum of the half reactionswhere electrons lost = electrons gained:
REDOX Half Reactions
OXIDIZING AGENT REDUCING AGENT
Gains electrons
and is reduced (GER) and is oxidized (LEO)
Loses electrons
Oxidizing agents cause the oxidation of other substances. Reducing agents cause the reduction of other substance.
2 Na + Cl2 → 2 Na+ + 2 Cl- + energy
RA OA
Q. Label the reducing agent (RA) andoxidizing agent (OA) in the reaction:
OA RA_________________________________________
• The stronger RA and OA =reactants; reactants exchangeelectrons spontaneously andenergy is released
• The weaker RA and OA productsdo not exchange electrons
2 Na + Cl2 → 2 Na+ + 2 Cl- + energy RA OA
Q. Based on the reaction below between Naand Cl2, compare sodium metal and chlorideion as reducing agents (RA)
OA RA_________________________________________
a) Cl- > Nab) Na > Cl-
c) Cl2 > Na+
d) Na+ > Cl-
2 Na + Cl2 → 2 Na+ + 2 Cl- + energy RA OA
Q. Based on the reaction below between Naand Cl2, rank the oxidizing agents (OA)
OA RA_________________________________________
Answer: ____ > _____Cl2 Na+
•Note that the metal Na = RA but its metal ion Na+ = OA
1A VIIIA1H1s1 IIA IIIA IVA VA VIA VIIA
2He1s2
3Li2s1
4Be2s2
5B
2s22p1
6C
2s22p2
7N
2s22p3
8O
2s22p4
9F
2s22p5
1 0Ne
2s22p6
1 1Na3s1
1 2Mg3s2 IIIB IVB VB VIB VIIBVIIIB ⇔VIIIB IB IIB
1 3Al
3s23p1
1 4Si
3s23p2
1 5P
3s23p3
1 6S
3s23p4
1 7Cl
3s23p5
1 8Ar
3s23p6
1 9K4s1
2 0Ca4s2
2 1Sc
3d14s2
2 2Ti
3d24s2
2 3V
3d34s2
2 4Cr
3d54s1
2 5Mn
3d54s2
2 6Fe
3d64s2
2 7Co
3d74s2
2 8Ni
3d84s2
2 9Cu
3d1 04s1
3 0Zn
3d1 04s2
3 1Ga
4s24p1
3 2Ge
4s24p2
3 3As
4s24p3
3 4Se
4s24p4
3 5Br
4s24p5
3 6Kr
4s24p6
3 7Rb5s1
3 8Sr5s2
3 9Y
4d15s2
4 0Zr
4d25s2
4 1Nb
4d35s2
4 2Mo
4d55s1
4 3Tc
4d55s2
4 4Ru
4d75s1
4 5Rh
4d85s1
4 6Pd
4d10
4 7Ag
4d1 05s1
4 8Cd
4d1 05s2
4 9In
5s25p1
5 0Sn
5s25p2
5 1Sb
5s25p3
5 2Te
5s25p4
5 3I
5s25p5
5 4Xe
5s25p6
5 5Cs6s1
5 6Ba6s2
5 7La*
5d16s2
7 2Hf
5d26s2
7 3Ta
5d36s2
7 4W
5d46s2
7 5Re
5d56s2
7 6Os
5d66s2
7 7Ir
5d76s2
7 8Pt
5d96s1
7 9Au
5d1 06s1
8 0Hg
5d1 06s2
8 1Tl
6s26p1
8 2Pb
6s26p2
8 3Bi
6s26p3
8 4Po
6s26p4
8 5At
6s26p5
8 6Rn
6s26p6
8 7Fr7s1
8 8Ra7s2
8 9Ac#
6d17s2
1 0 4 +
6d27s2
1 0 5 +6d37s2
1 0 6 +6d47s2
1 0 7 +6d57s2
1 0 8 +6d67s2
1 0 9 +6d77s2
+ Element synthesized,but no official name assigned
• Metals = reducing agents (LEO)
• Metal ions IA and IIA = oxidizing agents (GER)
• Other Metal ions = oxidizing or reducing agents
Multiple oxidation state metal ions
Example: Sn = 0, 2+ and 4+
Sn2+ ion can gain electrons = OA:
Sn2+ ion can lose electrons = RA: Sn2+ → Sn4+ + 2 e-
Some metal ions can act as an oxidizing orreducing agent!
Sn2+ + 2 e- → Sn
Predicting Redox Strength
Electronegativity and RedoxStrength
Electronegativity of the elements 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 IA IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA H 2.1
Li 1.0
Be 1.5
B 2.0
C 2.5
N 3.0
O 3.5
F 4.0
Na 0.9
Mg 1.2
Al 1.5
Si 1.8
P 2.1
S 2.5
Cl 3.0
K 0.8
Ca 1.0
Sc 1.3
Ti 1.5
V 1.6
Cr 1.6
Mn 1.5
Fe 1.8
Co 1.8
Ni 1.8
Cu 1.9
Zn 1.6
Ga 1.6
Ge 1.8
As 2.0
Se 2.4
Br 2.8
Rb 0.8
Sr 1.0
Y 1.2
Zr 1.4
Nb 1.6
Mo 1.8
Tc 1.9
Ru 2.2
Rh 2.2
Pd 2.2
Ag 1.9
Cd 1.7
In 1.7
Sn 1.8
Sb 1.9
Te 2.1
I 2.5
Cs 0.7
Ba 0.9
La -Lu
Hf 1.3
Ta 1.5
W 1.7
Re 1.9
Os 2.2
Ir 2.2
Pt 2.2
Au 2.4
Hg 1.9
Tl 1.8
Pb 1.8
Bi 1.9
Po 2.0
At 2.2
Fr 0.7
Ra 0.9
Ac 1.1
Th 1.3
Pa 1.5
U 1.7
Np-
N o 1.3
= Metalloids = Nonmetals = Metals
Electronegativity and Redox Strength
• Electronegativity values (p.222, manual) reflect anelements attraction for electrons when forming a bond
IA IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA H 2.1
Li 1.0
Be 1.5
B 2.0
C 2.5
N 3.0
O 3.5
F 4.0
Na 0.9
Mg 1.2
Al 1.5
Si 1.8
P 2.1
S 2.5
Cl 3.0
K 0.8
Ca 1.0
Sc 1.3
Ti 1.5
V 1.6
Cr 1.6
Mn 1.5
Fe 1.8
Co 1.8
Ni 1.8
Cu 1.9
Zn 1.6
Ga 1.6
Ge 1.8
As 2.0
Se 2.4
Br 2.8
Rb 0.8
Sr 1.0
Y 1.2
Zr 1.4
Nb 1.6
Mo 1.8
Tc 1.9
Ru 2.2
Rh 2.2
Pd 2.2
Ag 1.9
Cd 1.7
In 1.7
Sn 1.8
Sb 1.9
Te 2.1
I 2.5
Cs 0.7
Ba 0.9
La -Lu
Hf 1.3
Ta 1.5
W 1.7
Re 1.9
Os 2.2
Ir 2.2
Pt 2.2
Au 2.4
Hg 1.9
Tl 1.8
Pb 1.8
Bi 1.9
Po 2.0
At 2.2
Fr 0.7
Ra 0.9
Ac 1.1
Th 1.3
Pa 1.5
U 1.7
Np-
N o 1.3
Q. Where are the best oxidizing agentslocated in the electronegativity table?
Note: The element O is in the area (upper right corner)
IA IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA H 2.1
Li 1.0
Be 1.5
B 2.0
C 2.5
N 3.0
O 3.5
F 4.0
Na 0.9
Mg 1.2
Al 1.5
Si 1.8
P 2.1
S 2.5
Cl 3.0
K 0.8
Ca 1.0
Sc 1.3
Ti 1.5
V 1.6
Cr 1.6
Mn 1.5
Fe 1.8
Co 1.8
Ni 1.8
Cu 1.9
Zn 1.6
Ga 1.6
Ge 1.8
As 2.0
Se 2.4
Br 2.8
Rb 0.8
Sr 1.0
Y 1.2
Zr 1.4
Nb 1.6
Mo 1.8
Tc 1.9
Ru 2.2
Rh 2.2
Pd 2.2
Ag 1.9
Cd 1.7
In 1.7
Sn 1.8
Sb 1.9
Te 2.1
I 2.5
Cs 0.7
Ba 0.9
La -Lu
Hf 1.3
Ta 1.5
W 1.7
Re 1.9
Os 2.2
Ir 2.2
Pt 2.2
Au 2.4
Hg 1.9
Tl 1.8
Pb 1.8
Bi 1.9
Po 2.0
At 2.2
Fr 0.7
Ra 0.9
Ac 1.1
Th 1.3
Pa 1.5
U 1.7
Np-
N o 1.3
Q. Where are the best reducing agentslocated in the electronegativity table?
Note: The element Ra is in the area (lower left hand corner)
Part IA. Metal reactions with water
• Rank the reducing agent strength of themetals Na, K, Mg, and Ca from experimentalobservations.
• Correlate reactivity results with the positionof the metal in the periodic table.
IA IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA H 2.1
Li 1.0
Be 1.5
B 2.0
C 2.5
N 3.0
O 3.5
F 4 . 0
Na 0.9
Mg 1.2
Al 1.5
Si 1.8
P 2.1
S 2.5
Cl 3.0
K 0.8
Ca 1.0
Sc 1.3
Ti 1.5
V 1.6
Cr 1.6
Mn 1.5
Fe 1.8
Co 1.8
Ni 1.8
Cu 1 . 9
Zn 1.6
Ga 1.6
Ge 1.8
As 2.0
Se 2.4
Br 2.8
Rb 0.8
Sr 1.0
Y 1.2
Zr 1.4
Nb 1.6
Mo 1.8
Tc 1.9
Ru 2.2
Rh 2.2
Pd 2.2
Ag 1.9
Cd 1.7
In 1.7
Sn 1.8
Sb 1.9
Te 2.1
I 2.5
Cs 0.7
Ba 0.9
La -Lu
Hf 1.3
Ta 1.5
W 1.7
Re 1.9
Os 2.2
Ir 2.2
Pt 2.2
Au 2.4
Hg 1.9
Tl 1.8
Pb 1.8
Bi 1.9
Po 2.0
At 2.2
Fr 0.7
Ra 0.9
Ac 1.1
Th 1.3
Pa 1.5
U 1.7
Np-
N o 1.3
Q. Predict the RA strength of Mg and Ca based onposition and electronegativity values.
Ca Mg____> _____
Experimental Comparison of Ca and Mg
Metal + Water → metal hydroxide + H2(g) RA OA OA RA
Example: Mg(s) + 2HOH(l) → Mg(OH)2(s) + H2(g)
Ca > Mg
DEMO
RA: ________________
Experimental Comparison of Ca and Mg
IA IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA H 2.1
Li 1.0
Be 1.5
B 2.0
C 2.5
N 3.0
O 3.5
F 4 . 0
Na 0 . 9
Mg 1 . 2
Al 1.5
Si 1.8
P 2.1
S 2.5
Cl 3.0
K 0 . 8
Ca 1 . 0
Sc 1.3
Ti 1.5
V 1.6
Cr 1.6
Mn 1.5
Fe 1.8
Co 1.8
Ni 1.8
Cu 1 . 9
Zn 1.6
Ga 1.6
Ge 1.8
As 2.0
Se 2.4
Br 2.8
Rb 0.8
Sr 1.0
Y 1.2
Zr 1.4
Nb 1.6
Mo 1.8
Tc 1.9
Ru 2.2
Rh 2.2
Pd 2.2
Ag 1.9
Cd 1.7
In 1.7
Sn 1.8
Sb 1.9
Te 2.1
I 2.5
Cs 0.7
Ba 0.9
La -Lu
Hf 1.3
Ta 1.5
W 1.7
Re 1.9
Os 2.2
Ir 2.2
Pt 2.2
Au 2.4
Hg 1.9
Tl 1.8
Pb 1.8
Bi 1.9
Po 2.0
At 2.2
Fr 0.7
Ra 0.9
Ac 1.1
Th 1.3
Pa 1.5
U 1.7
Np-
N o 1.3
Q. Predict the RA strength of K and Na compared to Mgand Ca based on electronegativity values.
K Na Ca Mg____> _____ > _____ > _____
Reactivity of K and Na
Experimental determination of the reactivityof K and Na compared to Ca and Mg.
DEMO
Experimental Comparison of K, Na, Ca, and Mg
RA: K > Na > Ca > Mg
• Prediction from electronegativity values andexperimental results agree
Na skitters around the K skitters around the water surface water surface and ignites
Part I B. Predicting Metal Reactivity.
• Experimentally determine the reducingagent (RA) strength of four teamassigned metals
Information:• Only three of the four metals will be provided• Four of the assigned metal’s ions will beprovided
Part 1B Experiment Design
Example• You need to determine the reducing agentstrength of Pb, Cu, and Ag.
Information:• Solutions of metal ions Pb2+, Cu2+, Ag+ inthe form of 0.10 M metal ion nitrate salts• Cu and Ag only (i.e., Pb is unavailable)
Table Design for Part 1B.
Ag+ Cu2+ Pb2+
Ag
Cu
Pb
Reducing agents (metals) on one side andoxidizing agents (metal ions) on other side.
Create a table for recording data (pre-lab).
Part 1B experiment
Ag+ Cu2+ Pb2+
Ag NO √
Cu √ NO
Pb NO
Combine different available metals andmetal ions (0.10 M metal ion nitrates)
Metal and Metal ion reactions
Cu(s) + AgNO3(aq)→ ? Ag(s) + Cu(NO3)2(aq) → ?
DEMO
Q. Based on experiment results, rank:-The oxidizing agents (Ag+ and Cu2+)- The reducing agents (Ag and Cu)
Cu(s) + Ag+(aq) → YES Ag(s) + Cu2+(aq) → NO
Cu AgOA: ______>______ RA: ___ >_____Ag+ Cu2+
Metal and Metal Ion Reactions
Cu(s) + 2 Ag+(aq) 2 Ag(s) + Cu2+(aq)
RA: Cu > Ag OA: Ag+ > Cu2+
• Stronger RA and OA = Reactants
Part 1B experiment
Ag+ Cu2+ Pb2+
Ag NO NO √
Cu YES NO √
Pb NO
Enter results into Part 1B Table Test remaining available metal - metal ioncombinations
Metal and Metal ion reactions
Cu(s) + Pb(NO3 )2(aq)→ ? Ag(s) + Pb(NO3)2(aq) → ?
DEMO
Part 1B experiment
Ag+ Cu2+ Pb2+
Ag NO NO NO
Cu YES NO NO
Pb NO
Enter results into Part 1B Table
Ag+ Cu2+ Pb2+
Ag NO NO NO
Cu YES NO NO
Pb NO
Pb > Cu > Ag
Q. Complete the table below and indicate thecomparative RA strength of Ag, Cu, and Pb.
YES YES
RA strength: __________________
2
1
0
Questions?Contact [email protected]