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Exercises

Exercises. P257 B1. F –O–O–F d O–O = 1.217 Ǻ B. O. = 1 H –O–O–H d O–O = 1.48 Ǻ B. O. = 1 O–O 2– d O–O = 1.49 Ǻ B. O. = 1 Electronegativity: reduce Electron density of O atom, then reduce Lone paired electrons repulsion

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Exercises

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  1. Exercises

  2. P257 B1 • F–O–O–F dO–O = 1.217 Ǻ B. O. = 1 • H–O–O–H dO–O = 1.48 Ǻ B. O. = 1 • O–O2– dO–O = 1.49 Ǻ B. O. = 1 • Electronegativity: reduce Electron density of O atom, then reduce Lone paired electrons repulsion • F–O–F dO–F = ? Ǻ • F–O–O–F dO–F = 1.575 Ǻ

  3. P241 B13 • rO = 0.66 Ǻ rS = 1.04 Ǻ • dO–S = 1.70 Ǻ dS–S = 2.08 Ǻ • dO–S(SO42–) = 1.44 Ǻ • dO–S(SO3) = 1.42 Ǻ S–O π, What type ? • S2O32– S2O42– S3O62– S4O62– • dO–S 1.47 1.51 • dS–S 2.01 2.39 2.15 2.12(2.02) • No S–S π, Group repulsion

  4. The Nitrogen Chapter 16 (p179)

  5. Inroduction • Valence shell E. C. 2S22P3 • To complete its valence shell: 1. gain electron to form nitride: Li3N 2. formation of covalent bond compounds: NH3, N2, RN=NR, NO2 3. combine 2 with gaining or losing electron: NH2–, NR4+

  6. Notes • Stable free bases: NO, NO2, R2N=O • NR3: 1. as lewis base 2. may be chiral, turn inversion, as an umbrela can turn inside out 3. usually be pyramidal, but N(SiMe3)3 • Propensity to form p-pπ bond, cis or trans forms, may be as a optical switch

  7. The Haber Process N2(g) + 3H2(g) NH3(g) Nitrogen Hydrides (read yourself) catalyst? Preparation of Nitric Acid Thermal decomposition of ammonium Salts

  8. Prepared by Raschig process: NH3 + NaOCl N2H4 + NaCl + H2O Aqueous N2H4 is a powerful reducing agent O2 + N2H4(aq) H2O2(aq) + N2 Hydrazine N2H4 Hydrazine is commonly used for the synthesis of herbicides and pesticides, blowing agents for foam rubber and plastics, rocket fuel and the removal of oxygen from boiler water

  9. Hydroxylamine and Azides • Hydroxylamine NH2OH 1. A weak base, comparing with ammonia 2. As a reducing agent [NH3OH]Cl • Azides (N3–) • preparation: NaNH2 and NaNO2 • Explosive, especially heavy metal salts • Like a halide ion, can act as a ligand

  10. Nitrogen Oxides

  11. Nitrogen Oxides

  12. Nitrogen Oxides

  13. Why no O=N–N=O ? • Both NO and NO2 are free bases • Both NO and NO2 can lose the single electron to give positive ions: NO+ and NO2+ • N2O3 andN2O4 dissolve in concentrated sulpheric acid giving nitrosonium, and nitrosonium and nitronium • NO and NO2 give N2O3 rN-N = 1.86Ǻ • NO2 and NO2 give N2O4 rN-N = 1.75Ǻ • Reaction of NO and NO should give N2O2. Why is there no N2O2 ? Low temperature, rN-N = 2.18Ǻ

  14. NO • Odd-electron molecule that does NOT form a stable dimer such as NO2 • -due to greater delocalization of odd electron in * orbital relative to delocalization of electron in HOMO of NO2 • Atmospheric NO is slow to convert to NO2 • -sources are gasoline engines, power plants, etc • -catalysts have been discovered for its decomposition • -none yet robust enough for practical application in automotive world

  15. Nitrous and nitric acids • Nitrous Acid (HNO2) • Unstable HNO2 NO + NO2 + H2O 2. As oxidizing (I–) and reducing (Cl2) agents • Nitric acids (HNO3) • Unstable HNO3 NO3– + NO2+ + H2O 2. As oxidizing agents

  16. NF3 Can be converted to N(V) NF3 + 2F2 + SbF3 [NF4+] [SbF6-] Halides Nitrogen • Fluorides exhibit the greatest variety Relatively unreactive -why isn’t the lone pair very active? Finding use as a plasma-cleaning gas -N-F bond thermolysis at ~500 °C -”Safe” source of F atoms Prepared by electrolysis of NH4F

  17. Copper Packed Reactor NH3 + F2 NF3 N2F4 N2F2 NHF2 NF3 pyramidal molecule with very low dipole moment What does this imply? Given the stability of NF3 there have been attempts to prepare NF5 These have proven unsuccessful. (Decomp as low as –140 °)

  18. N2F2 F-N=N-F N2F4 F2N-NF2 Halides Other nitrogen fluorides:

  19. NCl3 • Very different compound from NF3 • Volatile, explosive liquid • Why? • Oxidizing bleach for flour NBr3 Increasing Explosive Character • Deep red, explosive solid NI3 • Red-black, explosive solid • Also prepared as black explosive ammoniate • NI3•NH3 Compounds of Group 15 Elements Halides:

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