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Friday’s Exam

Topics: Thermodynamics Laws of thermodynamics enthalpy, entropy, and free energy free energy and equilibrium standard vs. non-standard states Electrochemistry oxidation states of elements in compounds recognizing redox reactions

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Friday’s Exam

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  1. Topics: Thermodynamics Laws of thermodynamics enthalpy, entropy, and free energy free energy and equilibrium standard vs. non-standard states Electrochemistry oxidation states of elements in compounds recognizing redox reactions writing half-reactions Determining E° from table of reduction half-reactions Diagraming Galvanic Cells The Nernst Equation Electrolysis and electrolytic cells Stoichiometry of electroplating Friday’s Exam Given Equations and constants: R = 8.314 J mol-1 K-1 or 0.008314 kJ mol-1 K-1 F= 96,500 (C mol-1 or J V-1 mol-1) DH°rx = SiDH°f,i(products) - SiDH°f,i(reactants) (S° or DG°f,imay be substituted for DH°f,i) DG = DH - TDSDG = DG° + RT lnQDG° = -RT lnK E = E - 0.0592/n log Q DG = -nFE

  2. +1 none +2 -2 -1 -3 +3 Periodic Table Transition Metals and Coordination compounds H He Li Mg B C N O F Ne Na Mg Al Si P S Cl Ar Transition metals - variable K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

  3. Types of Acids/Bases

  4. bond formed H H-N: + H+ H H H-N:H+ H H H-N→H H + Coordinate covalent bond (dative bond) one molecule provides both electrons (Lewis base) the other molecule accepts electron pair into an empty orbital (Lewis acid)

  5. Electronic Configuration review Mn [Ar] 4s2 3d5 Mn+1 [Ar] 3d6 Mn+2 [Ar] 3d5 Mn+5 [Ar] 3d2 Transition Metals – Oxidation states Sc Ti V Cr Mn Fe Co Ni Cu Zn +3 d0 +3 d1 +3 d2 0 d6 +1 d6 0 d8 0 d9 0 d10 +1 d10 +2 d10 +4 d0 +5 d0 +2 d4 +2 d5 +2 d6 +1 d8 +2 d8 +2 d9 +3 d3 +3 d4 +3 d5 +2 d7 +4 d2 +5 d2 +3 d6 +6 d0 +7 d0

  6. Transition Metals – Coordination compounds Transition metals often have empty d orbitals The TM ion can act a Lewis acid They form coordinate covalent bonds with other molecules (ligands) which act as Lewis bases by donating a lone pair of electrons to empty d orbitals. Coordination compounds may have > octet. The most common geometries are tetrahedral or octahedral. Also linear, square planar, trigonalbipyramid etc. Coordination compounds often absorb light in visible range and thus have various colors

  7. .. .. HOH HOH Cr 3+ :OH2 H2O: H2O: :OH2 Coordination compounds - example Hexaaquachromium (III) – complex ion [Cr(H2O)6]3+ coordination complex ion – H2O is ligand As neutral compound [Cr(H2O)6](NO3)3 cationanion

  8. Anionic ligands end in – o (chloro, nitro, hydroxo, etc.) Neutral ligand names either unchanged or common names (e.g. aqua, ammine, carbonyl, etc.)

  9. diethylenetriamine (dien) tridentate .. .. .. H2N-(CH2)2-N-(CH2)2-NH2 H Ethylenediamintetraacetato (edta) hexadentate -OOC – CH2 CH2 – COO- .. .. N – (CH2)2 - N -OOC – CH2 CH2 – COO- PolydentateLigands ethylenediamine (en) bidentate .. .. H2N-CH2-CH2-NH2

  10. Nomenclature — Coordination Compounds 1) Cation name 1st (leave a space) anion name • a) Ligands named in alphabetical order • b) ligand prefixes (ignore when alphabetizing ligands) • mondentate – di, tri, tetra, penta, hexa • (polydentate) – bis (2), tris (3), tetrakis (4) 3) Anionic ligands end in – o (chloro, nitro, hydroxo, etc.) Neutral ligand names either unchanged or common names are used (e.g. aqua, ammine, carbonyl, etc.) 5) Roman Numerals designate metal oxidation states (II). 6) -ate ending used for metals in anionic complex ions

  11. Student Satisfaction Surveys CHM 1120 section 001 See Blackboard site for link Evaluations open for completion until 11:59 PM on May 10

  12. K3[FeF6] Cu(NH3)2(H2O)22+ Potassium hexacyanomanganate(III) sodium tetracyanozincate(II) (NH4)2[Fe(H2O)F5] a) diammoniumaquapentafluoroferrate(III) b) ammonium aquapentafluoroferrate(III) c) ammonium aquapentafluoroiron(III) d) diammoniumaquapentafluoroiron(III) tetraamminedichlorocobalt(III) nitrate a) [(NH3)4Cl2Co]NO3 b) [Co(III)(NH3)4Cl2]NO3 c) [Co(NH3)4Cl2]NO3 c) [CoCl2(NH3)4]NO3

  13. Fe(CO)5 hexaamminechromium(III) tetrachlorocuprate(II) Rh(CN)2(en)2+ [Cr(NH3)4SO4]Cl

  14. Coordination compounds – geometry Coordination #geometryexample(s) 2 linear [Cu(CN)2]- 4 tetrahedral [Zn(CN)4]2- square planar [Ni(CN)4]2- 5 trigonal bipyramidal Fe(CO)5 square pyramidal [Ni(CN)5]3- 6 octahedral [Fe(CN)6]4-

  15. Used in cancer chemotherapy Isomers – same formula but different compounds. NH3 NH3 Cl Cl Pt Pt Cl NH3 Cl NH3 cis – pale yellow trans – dark yellow diamminedichloroplatinum (II) square planar

  16. dxz z y x d z2 z y x dxy, dxz, dyzelectron densitybetween axes dz2 and dx2-y2electron densitylocated along x & y axes

  17. t2g = dxy, dxz, dyz eg = dz2 & dx2-y2 z z y y x x dxy, dxz, dyzelectron densitybetween axes dz2 and dx2-y2along x & y axes Where do the ligands approach from in an octahedral coordination complex? a) along axes b) in between axes c) both

  18. Crystal Field Theory A ligand is a Lewis base – electron pair donor In transition metal atoms all 5 d orbitals have the same energy – They are called degenerate. The ligands may approach central metal ion/atom along axes, e.g octahedral, or between axes, e.g. tetrahedral. Ligands prefer to approach where d orbitals are ….? a) full b) half full c) empty These ligands will be repelled by the electrons occupying orbitals along the direction in which they approach. This is the concept of the crystal (electric) field. The repulsion caused by Ligand fields overlapping the Metal ion/atom field will raise the energy of the eg orbitals (octahedral) or the energy of the t2g orbitals (tetrahedral).

  19. Bonding in Coordination Compounds Isolated transition metal atom Bonded transition metal atom Crystal field splitting (D) is the energy difference between two sets of dorbitals in a metal atom when ligands are present

  20. Bonding in Coordination Compounds weak ligand field strong ligand field

  21. l nm10-3 10-1 100 103 105 107 109 1011 1013 m 10-12 10-10 10-9 10-6 10-4 10-2100 102 104 n1020 1018 1016 1014 1012 1010 108 106 104 s-1 grays xrays UV IR mwaves radio visible high energy low energy E = hn J = Js  s-1 h = 6.626 x 10-34 Js

  22. Spectrochemical Series Ligands influence the value of Doct by virtue of their crystal field strength. Strong field ligands produce larger splitting energy (Doct). Pg 970 I- < Br- < Cl- < OH- < F- < H2O< (COO)22- < NH3 < en < CN-< CO High spincomplexes>>>>>>>>>>>>>>>>>>>>>>> Low spin e.g. Ni2+ d8 octahedral complexes with …. H2O, bipyridine, en, NH3, glycine

  23. 500 600 400 700 Orange A450 Red A500 Yellow A400 Violet A550 Green A650 Blue A600 Light Violet blue green yellow orange red Color

  24. Orange A450 Red A500 Yellow A400 Violet A550 Green A650 Blue A600 I- < Br- < Cl- < F- < OH- < H2O< (COO)22- < NH3 < en < NO2- < CN- [Ni(H2O)6]2+ Ni(gly)3 [Ni(NH3)6]2+ [Ni(en)3]2+ [Ni(bipyr)3]2+

  25. Weak field ligand eg eg eg eg t2g t2g t2g t2g strong field ligand l l

  26. t2g tetrahedral eg

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