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Previously in Chem 104: unit cell, Z, at.wt related to density

Previously in Chem 104: unit cell, Z, at.wt related to density types of closest packing, ccp= fcc, hcp Ionic Unit Cells for CsCl and NaCl. TODAY QUIZ answer key out - send self-check by Tuesday 5PM Is Aluminum a stable solid? Born Haber Cycles “why doesn’t that solid exist”

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Previously in Chem 104: unit cell, Z, at.wt related to density

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  1. Previously in • Chem 104: • unit cell, Z, at.wt related to density • types of closest packing, ccp= fcc, hcp • Ionic Unit Cells for CsCl and NaCl • TODAY • QUIZ answer key out - send self-check by Tuesday 5PM • Is Aluminum a stable solid? • Born Haber Cycles • “why doesn’t that solid exist” • phase diagrams

  2. Born Haber Cycles Relate Lattice Enthalpy and Heat of Formation Energy DHf Must be (-) for a stable solid Elements in Standard States: M(s) , X2(g) ionic solid

  3. Born Haber Cycles Energy X(g) M+(g) DHEA M+(g) , X- (g) DHI.E. X- (g) M(g) DHBD DHsub DHlattice M(s) , X2(g) ionic solid, MX DHf must be (-) for a stable solid

  4. Born Haber Cycles Energy X(g) M+(g) DHEA M+(g) , X- (g) DHI.E. X- (g) M(g) DHBD DHsub DHlattice M(s) , X2(g) DHf ionic solid, MX DHf = DHsub + DHI.E + DHBD + DHEA+ DHlattice

  5. Born Haber Cycles Energy Cl(g) Na+(g) DHEA Na+(g) , Cl- (g) DHI.E. Cl- (g) Na(g) DHBD DHsub DHlattice Na(s) , Cl2(g) DHf ionic solid, NaCl DHf = DHsub + DHI.E + DHBD + DHEA+ DHlattice For NaCl: -381 = +108 + 496 + 121 – 349 - 757

  6. DHf = DHsub+ DHI.E + DHBD + DHEA+ DHlattice For NaCl: -381 = +108 + 496 + 121 – 349 - 757 For Al2O3: -2365 = 2(+150 + 5139) + 3/2 (493) + 3 (639) - 15,600 For NaO: +2230 = +108 + 5058 + ½ (493) + 639 - 3820 Positive DHf: NaO does not (can not) exist!

  7. What factors affect the parameters in the Born-Haber calculations? • HEA: • HI.E: • HBD: • Hsub: • Hlattice: Hlattice ~ Ulattice = C NA { (Z+)(Z-) d

  8. Solids and Phase Diagrams. Energy Pressure, P Temperature, T

  9. The Basics of a Phase Diagram What does the slope of this line tell us? solid liquid Pressure, P Triple point: gas Temperature, T

  10. H2O Phase Diagram liquid solid Pressure, P gas Temperature, T

  11. CO2 Phase Diagram solid liquid Pressure, P gas Temperature, T

  12. Fe-C (steel) Phase Diagram FCC (Fe3C) FCC (BCC) Steel Cast Iron

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