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Bell Ringer

Bell Ringer. 2NO(g) + O 2 (g) 2NO 2 (g) D H = -27 kcal. Which graph represents the reaction shown above?. A. B. Energy. Energy. Reaction Progress. Reaction Progress. C. D. Energy. Energy. Reaction Progress. Reaction Progress.

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Bell Ringer

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  1. Bell Ringer 2NO(g) + O2(g) 2NO2(g) DH = -27 kcal Which graph represents the reaction shown above? A B Energy Energy Reaction Progress Reaction Progress C D Energy Energy Reaction Progress Reaction Progress Source: 2004 VA Chemistry EOC Exam

  2. Homework Answers • A, B • B • C • B • A • C • Inter • Intra • Dispersion forces • Boiling Point • Amorphous • Higher • Dipole-dipole • Freezing • Hydrogen bonding • 30ºC • 1.0 atm • 40ºC • 47ºC • 0.4 atm

  3. Practice with Enthalpy Calculate DH for the following reactions: 2 KBr (s) + I2 (g) 2 KI (s) + Br2 (l) DHtotal = [2mol (-327.9 kJ/mol) + 1mol (0 kJ/mol)] - [2mol (-393.8 kJ/mol) + 1mol (0 kJ/mol)] DHtotal = 131.8 kJ ENDOTHERMIC 2 HCl (g) + 2 Ag 2 AgCl (s) + H2 (g) DHtotal = [2mol (-127.01 kJ/mol) + 1mol (0 kJ/mol)] - [2mol (- 92.31kJ/mol) + 2mol (0 kJ/mol)] DHtotal = -69.40 kJ EXOTHERMIC

  4. Entropy and Gibb’s Free Energy They work the same way!! “PRODUCTS – REACTANTS” DStotal = DSproducts - DSreactants at 298 K! DS > 0, entropy increases (more disorder) DS < 0, entropy decreases (less disorder) DGtotal = DGproducts - DGreactants at 298 K! DG > 0, not spontaneous DG < 0, spontaneous DG = 0, equilibrium

  5. How do H, S, and G Relate? not at 298 K! DG = DH - TDS Potassium bromide reacts with iodine at 345K. Will this reaction occur spontaneously? 2 KBr (s) + I2 (s) 2 KI (s) + Br2 (l) DHtotal = [2mol (-327.9 kJ/mol) + 1mol (0 kJ/mol)] - [2mol (-393.8 kJ/mol) + 1mol (0 kJ/mol)] DHtotal = 131.8 kJ DStotal = [2mol (106.3 J/mol K) + 1mol (152.21 J/mol K)] - [2mol(95.9 J/mol K) + 1mol (116.14 J/mol K)] DStotal = 56.87 J/ K

  6. 1000 J x 1 kJ How do H, S, and G Relate? DG = DH - TDS Potassium bromide reacts with iodine at 345K. Will this reaction occur spontaneously? 2 KBr (s) + I2 (s) 2 KI (s) + Br2 (l) DHtotal = 131.8 kJ = 131,800 J DStotal = 56.87 J/ K DG = 131,800 J – (345K)(56.87 J/K) DG = 131800 J – 19620.15 J DG = 112179.85 J 112,000 J = 112 kJ NOT SPONTANEOUS!

  7. Properties of Water Ms. Besal 3/24-27/2006

  8. Characteristics of Water O H • Bent Shape • Hydrogen Bonding • Liquid at Room Temperature • Requires great amount of energy to change (raise or lower) temperature • Expands as a solid • High boiling point • High surface tension • High heat of vaporization • “universal” solvent H

  9. How does the flow of heat change water? E GAS DHvap = 40.7 kJ/mol VAPORIZATION 100ºC D CONDENSATION C TEMP. LIQUID MELT 0ºC B DHfus = 6.02 kJ/mol A FREEZE SOLID TIME

  10. Phase Diagram of Water E B FREEZE C liquid pressure solid CONDENSATION MELT VAPORIZATION . A gas D SUBLIMATION DEPOSITION Tc temperature

  11. E B liquid solid C . pressure A D gas temperature A: Triple point – the temperature and pressure at which gas, liquid, and solid form of a substance all exist in equilibrium. B: Melting curve C: Vaporization curve D: Sublimation curve E: Critical point – the temperature and pressure above which gas cannot be liquefied no matter how much pressure is applied.

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