example: 2 na + cl 2 nacl - university of michigan
TRANSCRIPT
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E3 Redox: Transferring electrons
Session one of two• First hour: Discussion (E1)• 2nd and 3rd hour: Lab (E3, Parts 1 and 2A)
Oxidation-Reduction (Redox)
Example: 2 Na(s) + Cl2 (g) → 2 NaCl(s)
Reactions involve electron transfer. Change in charge (oxidation state) of reactants.
Gain of e’s = reduction (Cl → Cl- in NaCl)Lose of e’s = oxidation
(Na → Na+ in NaCl)
Loss of electrons (LEO) = oxidation Gain of electrons (GER) = reduction
Redox reaction
2 Na + Cl2 → 2 ΝaCl + energy
DEMO
LEO GER
2
2 Na + Cl2 → 2 Na + + 2 Cl-
Oxidation Reduction
2 ( ) ( )
( > in oxidation state) ( < in oxidation state)
Na → Na+ + e- Cl2 + 2e- → 2Cl-
Half reactions always written to show electron GAIN.
The final equation reflects the sum of the balanced halfreactions so that electrons lost = electrons gained:
REDOX Half ReactionsOXIDIZING AGENT REDUCING AGENT
Gains electronsand is reduced (GER) and is oxidized (LEO)
Loses electrons
An oxidizing agent brings about the oxidation of another substance.A reducing agent bring about the reduction of another substance.
Redox Agents
2 Na + Cl2 → 2 Νa+ + 2 Cl- + energyRA OA
Q. Identify the reducing agents (RA) and oxidizingagents (OA) in the reaction:
OA RA_________________________________________
1A VIIIA1H
1s1 IIA IIIA IVA VA VIA VIIA
2He1s2
3Li
2s1
4Be
2s2
5B
2s22p1
6C
2s22p2
7N
2s22p3
8O
2s22p4
9F
2s22p5
1 0Ne
2s22p6
1 1Na
3s1
1 2Mg
3s2 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 9K
4s1
2 0Ca
4s2
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 7Rb
5s1
3 8Sr
5s2
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 5Cs
6s1
5 6Ba
6s2
5 7
La*
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 7Fr
7s1
8 8Ra
7s2
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
Oxidation State versus Family Number
Metals lose electrons Non-metals gain electrons
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11A
18VIIIA
2IIA
- 513
IIIA
- 414
IVA
- 315
VA
- 216
VIA
-117
VIIA
2
He
1s2
5
B
2s22p1
6
C
2s22p2
7
N
2s22p3
8
O
2s22p4
9
F
2s22p5
1 0
Ne
2s22p6
3 IIIB
4 IVB
5 VB
6VIB
7VIIB
8VIIIB
9 !
10 VIIIB
11 IB
12 IIB
1 4
Si
3s23p2
1 5
P
3s23p3
1 6
S
3s23p4
1 7
Cl
3s23p5
1 8
Ar
3s23p6
3 3
As
4s24p3
3 4
Se
4s24p4
3 5
Br
4s24p5
3 6
Kr
4s24p6
5 2
Te
5s25p4
5 3
I
5s25p5
5 4
Xe
5s25p6
8 5
At
6s26p5
8 6
Rn
6s26p6
+ Element synthesized,
but no official name assigned
Nonmetals gain electrons and reduce (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
Family A Metals Q1. Maximum charge vs. family# ?Q2. Possible oxidation states of Sn?
Ions with multiple oxidation states
Reduction of Sn2+ ion:
Oxidation of Sn2+ ion: Sn2+ → Sn4+ + 2 e-
Q. Sn (Group IVA) has oxidation states of zero, plustwo, and plus four. Write half reactions depicting:
Sn2+ can act as an oxidizing or reducing agent inredox reactions!
Sn2+ + 2 e- → Sn
11A
18VIIIA
1H
1s12IIA
13IIIA
14IVA
15VA
16VIA
17VIIA
3Li
2s1
4Be
2s2 +2 !
+2 !
+2 !
+2 !
+2 !
1 1Na
3s1
1 2Mg
3s2
+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 9K
4s1
2 0Ca
4s2
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 7Rb
5s1
3 8Sr
5s2
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 5Cs
6s1
5 6Ba
6s2
5 7
La*
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 7Fr
7s1
8 8Ra
7s2
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 # ?
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Strength of Redox Agents
Example: 2 Na + Cl2 → 2 Νa+ + 2 Cl-
RA OA
RA: Na > Cl- OA: Cl2 > Na+
OA RA
The reactants are the stronger RAand OA and react spontaneously The non-reactive products are theweaker OA and RA.
_________________________________________
Redox agent strength
2 Sb + 3 Cl2 → 2 Sb3+ + 6 Cl-
OA RA
Q. Rank the strength of the reducing/oxidizing agentsin the reaction below:
RA strength:___ >___ OA strength: ___ >___
RA OA
Sb Cl - Cl2 Sb 3+
Reaction and Redox Strength
Cu(s) + Ag+(aq) → ? Ag(s) + Cu2+(aq) → ?
DEMO
If RA: Cu > Ag OA: Ag+ > Cu2+
Reactants
Reactions and Redox Strength
Cu(s) + Ag+(aq) → reaction
The weaker RA and OA do NOT react:
The stronger RA and OA react:
Ag(s) + Cu2+(aq) → no reaction
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Part I B. Predicting Metal Reactivity.
• Determine the reducing agent (RA) strength of fourteam assigned metals where the metal ions of allfour metals are available and only three of the fourmetals are available for experimental tests.
Experiment Design and Data Analysis
Example You need to determine the reducing agent strength of
Zn, Cu, and Mg.
ProblemAvailable: Solutions of Zn2+, Cu2+, and Mg2+. Zn and Cu only (i.e., Mg is unavailable)
Experiment Design for Part 1B.
•Mg•Cu•Zn
•Mg2+•Cu2+•Zn2+
Reducing agent species (metals) on one side andoxidizing agents species (metal ions) on other side.
Create a table for recording data (pre-lab).
Experiment Design and Data Analysis
Example:
Zn(s) + Cu2+ (aq) → reaction
Test available metal and metal ion combinations Record observations
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Check data. Does it make sense?
11# rxns.
1RxnCu
1RxnZn
# rxns.Cu2+Zn2+
“ These results don’t make sense!”
Only one combination of metal and metal ion should react spontaneously -- the stronger RA and OA!
•1•0•# rxns.
•0No•No•Cu
•1•ReactionNo•Zn
•# rxns.•Cu2+•Zn2+
Data Analysis
RA and OA strength are inverse:
RA: Zn > Cu OA: Cu2+ > Zn2+
This data makes sense: The stronger RA and OA show more reactions!
No•Mg•NoNo•No•Cu•No•Rxn.No•Zn
•Mg2+•Cu2+•Zn2+
Reducing Agent Strength of Mg, Zn, and Cu?
Mg > Zn > Cu
Q2. Comparative RA strength of the metals?
Q1. Complete the table below.
Rxn Rxn
RA strength: _______________
Part I A. Metal reactions with water.
• Rank the reducing agent strength of the metals Na,K, Mg, and Ca from experimental observations.
• Correlate the results with the position of the metalin the periodic table.
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Experimental Comparison of Ca and Mg
Metal + Water → metal hydroxide + H2(g) RA OA OA RAExample: Mg(s) + 2HOH(l) → Mg(OH)2(s) + H2(g)
Ca > Mg
DEMO
RA: ________________
Reactivity of K and Na
Experimental determination of the reactivity of K andNa compared to Ca and Mg.
DEMO
Experimental Comparison of K, Na, Ca, and Mg
RA: K > Na > Ca > Mg
Na skitters around the K skitters around the water surface water surface and ignites
Electronegativity of the elements1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17IA IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA
H2.1Li1.0
Be1.5
B2.0
C2.5
N3.0
O3.5
F4.0
Na0.9
Mg1.2
Al
1.5
Si1.8
P2.1
S2.5
Cl3.0
K0.8
Ca1.0
Sc1.3
Ti1.5
V1.6
Cr1.6
Mn1.5
Fe1.8
Co1.8
Ni1.8
Cu1.9
Zn1.6
Ga1.6
Ge1.8
As2.0
Se2.4
Br2.8
Rb0.8
Sr1.0
Y1.2
Zr1.4
Nb1.6
Mo1.8
Tc1.9
Ru2.2
Rh2.2
Pd2.2
Ag1.9
Cd1.7
In1.7
Sn1.8
Sb1.9
Te2.1
I2.5
Cs0.7
Ba0.9
La-Lu
Hf1.3
Ta1.5
W1.7
Re1.9
Os2.2
Ir2.2
Pt2.2
Au2.4
Hg1.9
Tl1.8
Pb1.8
Bi1.9
Po2.0
At2.2
Fr0.7
Ra0.9
Ac1.1
Th1.3
Pa1.5
U1.7
Np- No1.3
= Metalloids = Nonmetals = Metals
RA and OA Predictions from Electronegativity values = Electron pulling power of an atom when part of a bond
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IA IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA
H2.1Li1.0
Be1.5
B2.0
C2.5
N3.0
O
3.5F4.0
Na0.9
Mg1.2
Al
1.5
Si1.8
P2.1
S2.5
Cl3.0
K0.8
Ca1.0
Sc1.3
Ti1.5
V1.6
Cr1.6
Mn1.5
Fe1.8
Co1.8
Ni1.8
Cu1.9
Zn1.6
Ga1.6
Ge1.8
As2.0
Se2.4
Br2.8
Rb0.8
Sr1.0
Y1.2
Zr1.4
Nb1.6
Mo1.8
Tc1.9
Ru2.2
Rh2.2
Pd2.2
Ag1.9
Cd1.7
In1.7
Sn1.8
Sb1.9
Te2.1
I2.5
Cs0.7
Ba0.9
La-Lu
Hf1.3
Ta1.5
W1.7
Re1.9
Os2.2
Ir2.2
Pt2.2
Au2.4
Hg1.9
Tl1.8
Pb1.8
Bi1.9
Po2.0
At2.2
Fr0.7
Ra
0.9Ac1.1
Th1.3
Pa1.5
U1.7
Np- No1.3
Q. Predict the RA strength of K compared to Na, Mg,and Ca based on position and electronegativity values.
K > Na > Ca > Mg____> _____ > _____ > _____
IA IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA
H2.1Li1.0
Be1.5
B2.0
C2.5
N3.0
O3.5
F4.0
Na0.9
Mg1.2
Al
1.5
Si1.8
P2.1
S2.5
Cl3.0
K0.8
Ca1.0
Sc1.3
Ti1.5
V1.6
Cr1.6
Mn1.5
Fe1.8
Co1.8
Ni1.8
Cu1.9
Zn1.6
Ga1.6
Ge1.8
As2.0
Se2.4
Br2.8
Rb0.8
Sr1.0
Y1.2
Zr1.4
Nb1.6
Mo1.8
Tc1.9
Ru2.2
Rh2.2
Pd2.2
Ag1.9
Cd1.7
In1.7
Sn1.8
Sb1.9
Te2.1
I2.5
Cs0.7
Ba0.9
La-Lu
Hf1.3
Ta1.5
W1.7
Re1.9
Os2.2
Ir2.2
Pt2.2
Au2.4
Hg1.9
Tl1.8
Pb1.8
Bi1.9
Po2.0
At2.2
Fr0.7
Ra
0.9Ac1.1
Th1.3
Pa1.5
U1.7
Np- No1.3
Q. Where are the best reducing and oxidizing agents located?
Caution: Attraction of metal or nonmetal ion for electrons in abond is different from its metal or nonmetal element.
Questions?Contact [email protected]