4b.Lec06E3W10 - Redox Reminders Experiment 3 Session...

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Unformatted text preview: Redox Reminders Experiment 3 Session 2 (Three hour lab) Complete Experiment 3 Parts 2B and 3 Complete team report Complete discussion presentation 2 Na + Cl2 → 2 NaCl + energy • Involve a transfer of electrons between a reducing agent (e.g., Na) and an oxidizing agent (e.g., Cl2) Redox Reminders Oxidizing Agent Reducing Agent ClNa strength Parts 2A and 2B Compare the properties and reactivity of the halogens and halides strength Cl2 Na+ BACKGROUND INFORMATION • The stronger OA and RA (Cl2 and Na) react spontaneously. • The weaker OA and RA (Na+ and Cl-) do NOT react (i.e. exchange electrons) spontaneously Parts 2A and 2B 1 1A 1 Halogens (Family VIIA) 18 VIIIA Compare the properties and reactivity of the halogens and halides H 1 s1 2 IIA 4 Q. Possible oxidation states? Answer: 0 or -1 13 5 14 6 15 7 16 8 2 IIIA IVA VA VIA VIIA B 13 17 9 He 1 s2 3 Li 2s1 11 Be 2s2 12 C 14 N 15 O 16 F 17 10 Ne 18 2 s2 2 p1 2 s2 2 p2 2 s2 2 p3 2 s2 2 p4 2 s2 2 p5 2 s2 2 p6 Na Mg BACKGROUND INFORMATION 3s1 19 K 3s2 20 3 4 5 6 7 8 9 10 IIIB IVB VB VIB VIIB VIIIB ! VIIIB 21 22 11 IB 29 1 1 2 Al Si P S Cl Ar IIB 3 s2 3 p1 3 s2 3 p2 3 s2 3 p3 3 s2 3 p4 3 s2 3 p5 3 s2 3 p6 30 10 3d1 04 s2 Ca Sc Y Ti Zr 23 V 24 Cr 25 Mn Fe Ru 26 27 Co Rh 28 Ni Pd Cu Ag 1 Zn 48 31 Ga 49 2 32 Ge 50 33 As 51 34 Se 52 35 Br 53 36 Kr 54 4s1 37 5s1 55 6s1 87 Rb Sr Cs Fr 4s2 4 s2 3d1 4 s2 3d2 4 s2 3d3 4 s1 3d5 4 s2 3d5 4 s2 3d6 4 s2 3d7 4 s2 3d8 4s 3d 38 39 40 41 42 43 44 45 46 47 4 s2 4 p1 4 s2 4 p2 4 s2 4 p3 4 s2 4 p4 4 s2 4 p5 4 s2 4 p6 Nb Mo Tc 5s2 5 s2 4d1 5 s2 4d2 5 s2 4d3 5 s1 4d5 5 s2 4d5 5 s1 4d7 5 s1 4d8 4d1 0 5s 4d 4d 5s 5 s2 5 p1 5 s2 5 p2 5 s2 5 p3 5 s2 5 p4 5 s2 5 p5 5 s2 5 p6 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 1 10 10 2 6s2 6 s2 5d1 6 s2 5d2 6 s2 5d3 6 s2 5d4 6 s2 5d5 6 s2 5d6 6 s2 5d7 6 s1 5d9 6s 5d 5d 6s 6 s2 6 p1 6 s2 6 p2 6 s2 6 p3 6 s2 6 p4 6 s2 6 p5 6 s2 6 p6 88 10 Cd 10 In Sn Sb Te I Xe Ra Ac# 89 104 105 + + 106 107 108 + + + 109 + + Element synthesized, but no official name assigned 7s1 222324252627 7s2 7 s2 6d1 7 s 6d 7 s 6d 7 s 6d 7 s 6d 7 s 6d 7 s 6d 1 Halogens HALOGENS Chlorine C l 2 ( g) Bromine Br2(l) Increasing molecular weight Iodine I2(s ) Cl2 = Chlorine Diatomic NONPOLAR molecules Oxidation state = zero Oxidizing agents that react to form halides: Cl2 + 2 e- → 2 Cl- Halogens HALIDES The halogens are provided in lab in water solution. Cl- in NaCl(s) Exist as ions in salts Br2(aq) (Bromine water) I2(aq) (Iodine water) Salt names end in ide (e.g., sodium bromide…) Oxidation state = -1 Reducing agents Halides The halides are provided in lab as sodium salts in water solution. Sodium salts of the halides Sodium halide (s) Sodium halide (aq) • One cannot visually distinguish between the different sodium halides in the solid form or in water solution The sodium salts of the halides visually look the same in the solid state and in aqueous solution. 2 Part 2B. Reactivity of the Halogens and Halides. Part 2B Information Collect experimental data on the comparative - oxidizing agent strength of the halogens - reducing agent strength of the halides. Br2(aq) (Bromine water) I2(aq) (Iodine water) • It is difficult to visually distinguish between bromine in water and iodine in water. Solvent extraction and visual ID of Halogens Solvent extraction and visual ID of Halogens • The halogens have different colors in hexane DEMO ID of Halogen (e.g. Iodine) by addition of Hexane OA Strength of Br2 versus I2? IA Q. How do Br2 and I2 compare as oxidizing agents solely based on electronegativity values? IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA •I • I2 •Br2 •Br See expanded Table in manual • Oxidizing agents are on one side of the Table and reducing agents on the other. Will Br2 gain an electron from I - or will I2 g ain an electron from Br -? H 2.1 Li 1.0 Na 0.9 K 0.8 Rb 0.8 Cs 0.7 Fr 0.7 Be 1.5 Mg 1.2 Ca 1.0 Sr 1.0 Ba 0.9 Ra 0.9 Sc 1.3 Y 1.2 La -Lu Ac 1.1 Ti 1.5 Zr 1.4 Hf 1.3 Th 1.3 V 1.6 Nb 1.6 Ta 1.5 Pa 1.5 Cr 1.6 Mo 1.8 W 1.7 U 1.7 BC 2.0 2.5 Al Si 1.5 1.8 Mn Fe Co Ni Cu Zn Ga Ge 1.5 1.8 1.8 1.8 1.9 1.6 1.6 1.8 Tc Ru Rh Pd Ag Cd In Sn 1.9 2.2 2.2 2.2 1.9 1.7 1.7 1.8 Re Os Ir Pt Au Hg Tl Pb 1.9 2.2 2.2 2.2 2.4 1.9 1.8 1.8 Np- N o 1.3 N 3.0 P 2.1 As 2.0 Sb 1.9 Bi 1.9 O 3.5 S 2.5 Se 2.4 Te 2.1 Po 2.0 F 4.0 Cl 3.0 Br 2.8 I 2.5 At 2.2 OA: Br2 I2 _ _____>_________ 3 Q. Based solely on electronegativity values, will a reaction occur between I2(aq) + NaBr(aq) → ? I2 (aq) + NaBr (aq) + hexane→ ? strength Oxidizing Agent Br2 I2 Reducing Agent BrI- Answer.______________________________ No. • I2 and Br - are the weaker oxidizing and reducing agents and therefore will NOT spontaneously react. Mix NaBr (aq) + I2 (aq) + hexane. Mix the phases. strength I2 (aq) + NaBr (aq) + hexane→ ? • After mixing the phases, determine the identity of the halogen present in the hexane phase Solvent extraction species I2 Na+ Br ? C l2 Br2 I2 I2 (aq)+ 2 NaBr ( aq) no reaction No Q. Has reaction occurred?________ B Enter results in data Table and continue to experiment Br2 (aq) + NaI (aq) + hexane→ ? II2 Br2 #rxns Data Analysis Br NO YES 1 0 # rxns 0 1 •The stronger RA and OA react & exhibit more rxns •The weaker RA and OA do not react spontaneously Mix NaI (aq) + Br2 (aq) + hexane. Mix the phases. Enter all results in the data Table Br2 I2 OA: ____ > ____ IRA: ____ > Br ____ 4 Part 3. Analysis of Redox Reactions Example: I2 + SnCl2 → ? Identify reactants and spectators - Design reference blank tests - Substitute non-reactive species (K+, Na+, NO3-) for an omitted species “Help. I spilled Iodine!” Identify products - Compare properties to known substances - Refer to the CRC Handbook. DEMO: Write a net reaction ID and rank strength of OAs and RAs Example: I2 + SnCl2 → ? Analysis of Reaction 1. Record Observations SnCl2(aq) + I2(aq) → Clear and colorless 2. Identify spectator and reactant species. Rxn: SnCl2(aq) + I2(aq) Reaction: SnCl2(aq) + I2(aq) → ? Reference Blank Test: Test: NaCl(aq) + I2(aq) n o rxn Conclusion: “Sn2+ is a reactant”. Sn(NO3)2(aq) + Conclusion: I2(aq) reaction “ Cl- is a spectator”. 5 3) Identify Products and Write a Net Reaction Observation: L ight brown I2(aq) color fades. 4). Indicate RA and OA comparative strength Sn2+aq) + RA I2(aq) → OA Sn4+ (aq) + 2I - (aq) OA RA and thus must form ____ IKnowledge: If I2 = OA, Sn2+ is a ________agent. reducing I2 Sn RA strength: ____ >___ OA strength: ___ >___ 4+ Sn2+ I“The reactants are the stronger OA and RA”. Sn4+ and thus must form ____ (rather than Sn0 ) Sn2+(aq) + I2(aq) → _2I-(aq) + Sn4+(aq) ______________ Q. Identify the reactants and products in the reaction, CoF3(aq) + KBr(aq) → ? given OA Strength: F2 > Co3 + > Br2 > K+ List the OA species and indicate OA strength Experiment 3 Exam Question OA F2 Co3+ Br2 K+ Q. Identify the reactants and products in the reaction, CoF3(aq) + KBr(aq) → ? given OA Strength: F2 > Co3 + > Br2 > K+ Q. Identify the reactants and products in the reaction, CoF3(aq) + KBr(aq) → ? given OA Strength: F2 > Co3 + > Br2 > K+ Circle all species actually present in the List the RA species and indicate RA strength OA F2 RA reaction mixture. OA F2 RA Co3+ FCo2+ FCo2+ Br2 K+ B rK Co3+ Br2 B rK K+ 6 Q. Identify the reactants and products in the reaction, CoF3(aq) + KBr(aq) → ? given OA Strength: F2 > Co3 + > Br2 > K+ Determine the species combination/s that will spontaneously react. OA F2 RA Q. Identify the products in the redox reaction, CoF3(aq) + KBr(aq) → ? given OA Strength: F2 > Co3 + > Br2 > K+ OA F2 RA FCo2+ FCo2+ Co3+ Br2 Co3+ Br2 Br K B rK K+ K+ Answer:______________ Co2+ + Br2 Answer:____________________. Co3+ and Br - will react Chem 125/126 Hourly I Exam Practice exam questions! You should be able to answer all hourly I exam questions upon completion of experiment 3. Exams on Ctools and the course web site: http:www.umich.edu/~chem125 7 ...
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This note was uploaded on 04/07/2010 for the course PSYCH 123 taught by Professor 123 during the Spring '10 term at University of Michigan.

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