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 nkerner@umich.edu