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E3 : Transferring electrons Oxidation-Reduction (Redox) . Reactions involve . . Change in charge (oxidation state) of reactants. Session one of two

First hour E2 discussion Reaction: 2 Na(s) + Cl2 (g) → 2 NaCl(s) Lab: Parts 1 and 2A

Gain e’s = reduction (Cl → Cl- in NaCl) Lose e’s = oxidation (Na → Na+ in NaCl)

Redox reaction

+ - 2 Na + Cl2 → 2 Νa + 2 Cl + energy LEO GER

DEMO . Loss of electrons (LEO) = oxidation . Gain of electrons (GER) = reduction

REDOX Half Reactions OXIDIZING AGENT Oxidation Reduction

( > in oxidation state) ( < in oxidation state) Gains electrons Loses electrons + - - - 2 ( Na → Na + e ) ( Cl 2 + 2 e → 2 Cl ) and is reduced (GER) and is oxidized (LEO)

. Half reactions always written to show electron GAIN. . The final equation reflects the sum of the balanced half reactions so that electrons lost = electrons gained: 2 Na + Cl → 2 Na + + 2 Cl- 2 → 2 2 .An oxidizing agent brings about the oxidation of another substance. .A reducing agent bring about the reduction of another substance.

1 Redox Agents Redox agent strength

Q. Identify the reducing agents (RA) and oxidizing Q. Rank the strength of the reducing/oxidizing agents agents (OA) in the reaction: in the reaction below: + - 2Sb + 3 Cl 2 Sb3+ + 6 Cl- 2 Na + Cl2 → 2 Νa + 2 Cl + energy 2 → OA RA RA OA OA RA RA OA

. The reactants are the stronger RA and OA and react spontaneously - . The non-reactive products are the Sb Cl 3+ RA strength:___ >___ OA strength: ___Cl2 >___ Sb weaker OA and RA.

Oxidation State versus Family Number gain electrons and reduce (GER)

1 18 1A VIIIA Metals lose electrons Non-metals gain electrons - 5 - 4 - 3 - 2 -1 2 1A VIIIA 2 13 14 15 16 17 He IIA 1s2 1 2 IIIA IVA VA VIAVIIA H He 5 6 7 8 9 10 2 1s1 IIA IIIA IVA VA VIA VIIA 1s B C N O F Ne 2 1 2 2 2 3 2 4 2 5 2 6 3 4 5 6 7 8 9 10 2s 2p 2s 2p 2s 2p 2s 2p 2s 2p 2s 2p Li Be B C N O F Ne 2s1 2s2 2s22p12s22p2 2s22p32s22p4 2s22p52s22p6 14 15 16 17 18

11 12 13 14 15 16 17 18 3 4 5 6 7 8 9 10 11 12 Si P S Cl Ar Na Mg Al Si P S Cl Ar IIIB IVB VB VIB VIIB VIIIB ⇔ VIIIB IB IIB 3s23p23s23p3 3s23p43s23p5 3s23p6 3s1 3s2 IIIB IVB VB VIB VIIBVIIIB ⇔ VIIIB IB IIB 3s23p13s23p2 3s23p33s23p4 3s23p53s23p6 33 34 35 36 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 As Se Br Kr K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 4s24p3 4s24p4 4s24p54s24p6 10 1 10 2 4s1 4s2 3d14s23d24s23d34s23d54s13d54s23d64s2 3d74s2 3d84s2 3d 4s 3d 4s 4s24p14s24p2 4s24p34s24p4 4s24p54s24p6 52 53 54 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Te I Xe Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 5s25p45s25p5 5s25p6 1 2 1 2 2 2 3 2 5 1 5 2 7 1 8 1 10 4d105s14d105s2 2 1 2 2 2 3 2 4 2 5 2 6 5s 5s 4d 5s 4d 5s 4d 5s 4d 5s 4d 5s 4d 5s 4d 5s 4d 5s 5p 5s 5p 5s 5p 5s 5p 5s 5p 5s 5p 85 86 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 At Rn Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 2 5 2 6 10 1 10 2 6s 6p 6s 6p 1 2 1 25d26s25d36s25d46s25d56s25d66s2 5d76s2 5d96s1 5d 6s 5d 6s 6s26p16s26p2 6s26p36s26p4 6s26p56s26p6 6s 6s 5d 6s + Element synthesized, Element synthesized, 87 88 89 104 105 106 107 108 109 + but no official name assigned Fr Ra Ac# + + + + + + but no official name assigned 7s1 7s2 6d17s26d27s26d37s26d47s26d57s26d67s2 6d77s2

+1 1 18 1A Family A Metals +3 +4 +5 +6 VIIIA Ions with multiple oxidation states 1 +2 Q1. Maximum charge vs. family# ? +1 +2 +3 +4 H 2 13 14 15 16 17 1s1 Q2. Possible oxidation states of Sn? VIIA IIA IIIA IVA VA VIA Q. Sn (Group IVA) has oxidation states of zero, plus 3 4 Li Be two, and plus four. Write half reactions depicting: 2s1 2s2 11 12 13 2+ Na Mg 3 4 5 6 7 8 9 10 11 12 Al Reduction of Sn ion: 1 2 VIIIB VIIIB 3s23p1 3s 3s IIIB IVB VB VIB VIIB ⇔ IB IIB 2+ 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Sn + 2 e- → Sn K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge 2+ 1 2 Oxidation of Sn ion: 4s1 4s2 4s23d1 4s23d2 4s23d3 4s13d5 4s23d5 4s23d6 4s23d7 4s23d8 4s 3d10 4s 3d10 4s24p1 4s24p2 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 2+ 4+ Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Sn → Sn + 2 e- 5s1 5s2 5s24d125s 24d2 5s24d3 5s14d5 5s23d5 5s14d7 5s14d8 4d10 5s14d10 5s24d10 5s25p1 5s25p2 5s25p3 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po . Multiple oxidation state ions such as Sn2+ can act as 6s1 6s2 6s25d1 6s25d2 6s25d3 6s25d4 6s24d5 6s25d6 5d76s2 6s15d9 6s15d10 6s25d10 6s26p1 6s26p2 6s26p3 6s26p4 87 88 89 104 105 106 107 108 109 + Element synthesized, an oxidizing or reducing agent in redox reactions! Fr Ra Ac# + + + + + + but no official name assigned 2 2 2 3 2 4 2 5 2 6 7 2 7s1 7s2 7s26d1 7s 6d 7s 7d 7s 6d 7s 3d 6s 6d 6d 7s

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1 Transition Metals 18 1A VIIIA Reactions and Redox Strength 1 Oxidation state vs. family # ? H 2 13 14 15 16 17 1s1 IIA IIIA IVA VA VIA VIIA Q. Write a spontaneous net reaction equation given: 3 4 Li Be RA: Cu > Ag OA: Ag+ > Cu2+ 2s1 2s2 +2 +2 +2 +2 +2 ↓ ↓ ↓ ↓ ↓ 11 12 +3 +4 +5 +6 +7 +2 +1 +2 13 Na Mg 3 4 5 6 7 8 9 10 11 12 Al 3s1 3s2 IIIB IVB VB VIB VIIB VIIIB ⇔ VIIIB IB IIB 3s23p1 reactants 19 20 21 22 23 24 25 26 27 28 29 30 31 32 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge 1 2 2 1 2 2 2 3 1 5 2 5 2 6 2 7 2 8 4s13d10 4s23d10 2 1 2 2 4s 4s 4s 3d 4s 3d 4s 3d 4s 3d 4s 3d 4s 3d 4s 3d 4s 3d 4s 4p 4s 4p + 2+ 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 Cu(______s) + ______2 Ag ( aq ) → → ______2 Ag(s) + ______Cu (aq) Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb 1 10 2 10 5s1 5s2 5s24d125s24d25s24d3 5s14d55s23d55s14d7 5s14d8 4d10 5s 4d 5s 4d 5s25p15s25p25s25p3 Stronger RA and OA Weaker RA and OA 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po react do NOT react 1 10 2 10 6s1 6s2 6s25d16s25d26s25d3 6s25d46s24d56s25d6 5d76s2 6s15d96s 5d 6s 5d 6s26p16s26p26s26p3 6s26p4 87 88 89 104 105 106 107 108 109 + Element synthesized, Fr Ra Ac# + + + + + + but no official name assigned 7s1 7s2 7s26d17s26d27s27d3 7s26d47s23d56s26d6 6d77s2

Reactions and Redox Strength Reactions and Redox Strength . The stronger RA and OA react:

Cu(s) + 2 Ag+(aq) → reaction Cu(s) + Ag+(aq) → ? Ag(s) + Cu2+(aq) → ? . The weaker RA and OA do NOT react:

DEMO Ag(s) + Cu2+(aq) → no reaction

Part I B. Predicting Metal Reactivity. Experiment Design and Data Analysis

. You need to determine the reducing agent strength of • Determine the reducing agent (RA) strength of four Zn, Cu, and Mg. team assigned metals where the metal ions of all four metals are available and only three of the four Problem metals are available for experimental tests. Available: Solutions of Zn2+, Cu2+, and Mg2+. Zn and Cu only (i.e., Mg is unavailable)

3 Experiment Design for Part 1B. Experiment Design and Data Analysis

. Create a table for recording data (pre-lab). . Test available metal and metal ion combinations . Check results -- does the data make sense? •Zn2+ •Cu2+ •Mg2+ •Zn Observations •Cu •Mg Reducing agent species (metals) on one side and oxidizing agents species (metal ions) on other side. Zn(s) + Cu2+ (aq) → reaction

Caution: Check data. Does it make sense? Data Analysis

Zn2+ Cu2+ # rxns. •Zn2+ •Cu2+ •# rxns. Zn Rxn 1 •Zn No •Reaction •1 Cu Rxn 1 •Cu •No No •0 # rxns. 1 1 •# rxns. •0 •1

This data makes sense: “ These results don’t make sense!” . The stronger RA and OA show more reactions! . RA and OA strength are inverse: . Only one combination of metal and metal ion should RA: Zn > Cu OA: Cu2+ > Zn2+ react spontaneously -- the stronger RA and OA!

Reducing Agent Strength of Mg, Zn, and Cu? Part I A. Metal reactions with water.

Q1. Complete the table below. • Rank the reducing agent strength of the metals Na, •Zn2+ •Cu2+ •Mg2+ K, Mg, and Ca from experimental observations. • Correlate the results with the position of the metal No •Rxn. •No •Zn in the periodic table. •Cu •No No •No •Mg Rxn Rxn No

Q2. Comparative RA strength of the metals? RA strength: Mg > Zn > Cu

4 RA and OA Predictions from Electronegativity values Comparison of Ca, Mg, and Na Electron pulling power of an atom when part of a bond 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 Metal + Water → metal hydroxide + H2(g) H RA OA OA RA 2.1 Li Be B C N O F Example: 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Na Mg Si P S Cl Mg + 2HOH → Mg(OH) + H Al (s) (l) 2(s) 2(g) 0.9 1.2 1.5 1.8 2.1 2.5 3.0 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br 0.8 1.0 1.3 1.5 1.6 1.6 1.5 1.8 1.8 1.8 1.9 1.6 1.6 1.8 2.0 2.4 2.8 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I DEMO 0.8 1.0 1.2 1.4 1.6 1.8 1.9 2.2 2.2 2.2 1.9 1.7 1.7 1.8 1.9 2.1 2.5 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At 0.7 0.9 -Lu 1.3 1.5 1.7 1.9 2.2 2.2 2.2 2.4 1.9 1.8 1.8 1.9 2.0 2.2 Fr Ra Ac Th Pa U Np- No RA: Na > Ca > Mg 0.7 0.9 1.1 1.3 1.5 1.7 1.3

= = Nonmetals = Metals

Q. Predict the RA strength of K compared to Na, Mg, Reactivity of K and Ca based on position and electronegativity values. IA IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA . Experimental comparison of the reactivity of K to Na, H Ca, and Mg. 2.1 Li Be B C N O F 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Na Mg Al Si P S Cl 0.9 1.2 1.5 1.8 2.1 2.5 3.0 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br 0.8 1.0 1.3 1.5 1.6 1.6 1.5 1.8 1.8 1.8 1.9 1.6 1.6 1.8 2.0 2.4 2.8 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I 0.8 1.0 1.2 1.4 1.6 1.8 1.9 2.2 2.2 2.2 1.9 1.7 1.7 1.8 1.9 2.1 2.5 Na skitters around the K skitters around the Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At water surface water surface and ignites 0.7 0.9 -Lu 1.3 1.5 1.7 1.9 2.2 2.2 2.2 2.4 1.9 1.8 1.8 1.9 2.0 2.2 Fr Ra Ac Th Pa U Np- No 0.7 0.9 1.1 1.3 1.5 1.7 1.3 RA: K > Na > Ca > Mg ____> _____ > _____ > _____ K > Na > Ca > Mg DEMO

Q. Where are the best reducing and oxidizing agents located? IA IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA H 2.1 Li Be B C N O F 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Na Mg Al Si P S Cl 0.9 1.2 1.5 1.8 2.1 2.5 3.0 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br 0.8 1.0 1.3 1.5 1.6 1.6 1.5 1.8 1.8 1.8 1.9 1.6 1.6 1.8 2.0 2.4 2.8 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I 0.8 1.0 1.2 1.4 1.6 1.8 1.9 2.2 2.2 2.2 1.9 1.7 1.7 1.8 1.9 2.1 2.5 Questions? Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At 0.7 0.9 -Lu 1.3 1.5 1.7 1.9 2.2 2.2 2.2 2.4 1.9 1.8 1.8 1.9 2.0 2.2 Contact [email protected] Fr Ra Ac Th Pa U Np- No 0.7 0.9 1.1 1.3 1.5 1.7 1.3 Caution: Attraction of metal or ion for electrons in a bond is different from its metal or nonmetal element.

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