Experiment Three Lab one: Parts 1 and 2A Lab two: Parts 2B and 3 1 1A 1 H 1s 1 2 IIA 3 Li 2s 1 1 1 Na 3s 1 1 9 K 4s 1 3 7 Rb 5s 1 5 5 Cs 6s 1 8 7 Fr 7s 1 4 Be 2s 2 1 2 Mg 3s 2 3 IIIB 4 IVB 5 VB 6 VIB 7 VIIB 8 VIIIB 2 0 2 1 Ca Sc 4s 2 4s 2 3d 1 3 8 3 9 Sr Y 5s 2 5s 2 4d 1 Halogens (Family VIIA) used in Parts 2 and 3 Q. Possible oxidation states? Answer: 9! 10 VIIIB 11 12 IB 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 Ti V Cr Mn Fe Co Ni Cu 4s 2 3d 2 4s 2 3d 3 4s 1 3d 5 4s 2 3d 5 4s 2 3d 6 4s 2 3d 7 4s 2 3d 8 4s 1 3d 10 4 0 Zr 4 1 Nb 4 2 Mo 4 3 Tc 4 4 Ru 4 5 Rh 4 6 Pd 5s 2 4d 2 5s 2 4d 3 5s 1 4d 5 5s 2 4d 5 5s 1 4d 7 5s 1 4d 8 4d 10 18 VIIIA 2 VIIA 17 1s 2 13 IIIA 14 IVA 15 VA 16 VIA He 5 6 7 8 9 1 0 B C N O F Ne 2s 2 2p 1 2s 2 2p 2 2s 2 2p 3 2s 2 2p 4 2s 2 2p 5 2s 2 2p 6 IIB 1 3 Al 1 4 Si 1 5 P 1 6 S 1 7 Cl 1 8 Ar 3s 2 3p 1 3s 2 3p 2 3s 2 3p 3 3s 2 3p 4 3s 2 3p 5 3s 2 3p 6 3 0 Zn 3d 1 0 4s 2 3 1 Ga 3 2 Ge 3 3 As 3 4 Se 3 5 Br 3 6 Kr 4s 2 4p 1 4s 2 4p 2 4s 2 4p 3 4s 2 4p 4 4s 2 4p 5 4s 2 4p 6 4 7 Ag 4 8 Cd 4 9 In 5 0 Sn 5 1 Sb 5s 1 4d 10 4d 1 0 5s 2 5s 2 5p 1 5s 2 5p 2 5s 2 5p 3 5 2 Te 5 3 I 5 4 Xe 5s 2 5p 4 5s 2 5p 5 5s 2 5p 6 5 6 5 7 7 2 7 3 7 4 7 5 7 6 7 7 7 8 7 9 8 0 8 1 8 2 8 3 8 4 8 5 8 6 Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 6s 2 6s 2 5d 1 6s 2 5d 2 6s 2 5d 3 6s 2 5d 4 6s 2 5d 5 6s 2 5d 6 6s 2 5d 7 6s 1 5d 9 6s 1 5d 10 5d 1 0 6s 2 6s 2 6p 1 6s 2 6p 2 6s 2 6p 3 6s 2 6p 4 6s 2 6p 5 6s 2 6p 6 8 8 8 9 1 0 4 1 0 5 1 0 6 1 0 7 1 0 8 1 0 9 + Element synthesized, Ra Ac # + + + + + + but no official name assigned 7s 2 7s 2 6d 1 7s 2 6d 2 7s 2 6d 3 7s 2 6d 4 7s 2 6d 5 7s 2 6d 6 7s 2 6d 7 Halogens used in Parts 2 and 3 Chlorine Bromine Iodine Cl 2 (g) (l) I 2 (s) Increasing molecular weight 1
HALOGENS Cl 2 = Chlorine Exist as diatomic NONPOLAR molecules Oxidation state = zero Oxidizing agents that react to form halides: Cl 2 + 2 e - 2 Cl - HALIDES Cl - in NaCl(s) Exist as anions in salts Salt names end in ide (e.g., sodium bromide ) Oxidation state = -1. Reducing agents Halogens (Parts 2 and 3) The halogens will be provided in water solution. Chlorine water Bromine water Iodine water similar in visual appearance 2
Halides (Parts 2 and 3) The halides are provided as sodium salts in water solution. Sodium halide (s) Sodium halide (aq) The sodium salts of the halides visually look the same in the solid state and in aqueous solution. Part 2A. Color and Solubility of the Halides and Halogens Determine and compare the color and solubility of the halides and halogens in water and hexane. Color of the Halogens The color of the halogens is solvent dependent. Example Iodine versus Iodine water (dilute and more concentrated) 3
Solvent Polarity Reminders Polar (e.g., water) and non-polar (e.g., hexane) liquids are immiscible. Polar and non-polar liquids form separate phases: Salt Solubility Reminders Salts are soluble and dissociate in polar solvents. Salts are NOT soluble and do not dissociate in nonpolar solvents. Like attracts like Q. A yellow-brown aqueous solution contains an unidentified halogen. If hexane is added to the solution two phases form where the upper phase is pink and the lower phase colorless. Identify the halogen + hexane Answer: 4
Part 2B. Reactivity of the Halogens and Halides. Collect experimental data on the reactivity of the halogens and halides. Discussion questions 3 and 4, p.96 OA Strength of Chlorine versus Bromine? Cl 2 # rxns. Cl - # rxns. See expanded Table, p.77 Table: Oxidizing agents on one side and reducing agents on the other side. Caution: Check data. Does it make sense? Cl - # rxns. Cl 2 No rxn 0 No rxn 0 # rxns. 0 0 These results don t make sense! One combination of halogen and halide should react -- the stronger OA and RA agent! 5
Interpreting Experiment Results 1) Cl 2 + 2 2 Cl - + OA RA RA OA 2) + 2 Cl - 2 + Cl 2 Reaction 1) or 2) should occur! 1) OA strength: > 2) OA strength: > Q. The electronegativity of chlorine = 3.0 and bromine = 2.8. Based strictly on electronegativity values, will (aq) + NaCl(aq) react? List the Oxidizing and reducing agent species and indicate the comparative strength Oxidizing Agent Cl 2 Reducing Agent Cl - Answer. Experiment Results Q. (aq) + NaCl (aq) reaction or no reaction? Add hexane (aq) + 2 NaCl (aq) 6
Interpreting Experiment Results Q2. Identify the species present in the upper and lower phases upon addition of hexane to the reaction mixture. Add hexane (aq) + 2 NaCl (aq) no reaction Part 3. Analysis of Redox Reactions Identify reactants and spectators in redox reactions. - Non-reactive redox species (K +, Na +, NO 3 - ) make good substitutes for an omitted species in tests. Identify products; write a net reaction - Compare properties to known substances - use the CRC Handbook. Rank the oxidizing or reducing agent strength of species in the reaction Example: I 2 + SnCl 2? Help. I spilled Iodine! : Add tin(ii) chloride to iodine spot! 7
Analysis of Reaction 1. Record Observations SnCl 2(aq) + I 2(aq) clear and colorless product 2. Design and Interpret Reference Blank Tests Reaction: SnCl 2(aq) + I 2(aq)? Reference Blank Test: NaCl (aq) + I 2(aq) Conclusion: 2. Design and Interpret Reference Blank Tests Reaction: SnCl 2(aq) + I 2(aq)? Reference Blank Test: Sn(NO 3 ) 2(aq) + I 2(aq) Conclusion: 8
3) Identify OA and RA Reactants Q. Identify the oxidizing and reducing agent reactants: Sn 2+ (aq) + I 2(aq)? 4) Identify Products and Write a Net Reaction Observation: Light brown I 2(aq) color fades. Knowledge: is the reducing agent. Sn 2+ (aq) + I 2(aq) 5). Strength of the Reducing and Oxidizing Agents? Sn 2+ aq) + I 2(aq) Sn4+ (aq) + 2I - (aq) RA strength: > OA strength: > The reactants are the stronger OA and RA. 9
Q. Identify the reactants in the redox reaction, CoF 3(aq) + KBr (aq)? given OA Strength: F 2 > Co 3 + > > K + List the species and indicate OA and RA strength: OA F 2 Co 3+ K + RA Q. Identify the reactants in the redox reaction, CoF 3(aq) + KBr (aq)? given OA Strength: F 2 > Co 3 + > > K + List the species and indicate OA and RA strength: OA F 2 Co 3+ K + RA F - Co 2+ K Q. Identify the reactants in the redox reaction, CoF 3(aq) + KBr (aq)? given OA Strength: F 2 > Co 3 + > > K + Note (circle) all species present in the reaction. OA F 2 Co 3+ K + RA F - Co 2+ K 10
Q. Identify the reactants in the redox reaction, CoF 3(aq) + KBr (aq)? given OA Strength: F 2 > Co 3 + > > K + Identify which species will react OA F 2 Co 3+ K + RA F - Co 2+ K Q. Identify the products in the redox reaction, CoF 3(aq) + KBr (aq)? given OA Strength: F 2 > Co 3 + > > K + OA F 2 Co 3+ K + RA F - Co 2+ K Answer: Chem 125/126 Exam Practice exam questions! You should be able to answer all hourly I exam questions upon completion of experiment 3. Exams and review notes on Ctools and course web site: http:www.umich.edu/~chem125 11