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2 Hg ( l ) + O 2 ( g ) 2 HgO ( s ) exothermic

Given:. Δ H – increasing or decreasing? favorable or unfav? Δ S – increasing or decreasing? favorable or unfav? Δ G – increasing or decreasing? favorable or unfav?. 2 Hg ( l ) + O 2 ( g ) 2 HgO ( s ) exothermic. Given:. What is Δ H for reaction of 2 moles of O 2 ?.

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2 Hg ( l ) + O 2 ( g ) 2 HgO ( s ) exothermic

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  1. Given: ΔH – increasing or decreasing? favorable or unfav? ΔS – increasing or decreasing? favorable or unfav? ΔG – increasing or decreasing? favorable or unfav? 2Hg(l) + O2(g) 2HgO(s) exothermic

  2. Given: What is ΔH for reaction of 2 moles of O2? 2Hg(l) + O2(g) 2HgO(s) ΔH°= -181kJ Calculate ΔH for the reaction of 100.0 grams of Hg.

  3. Given: 2Hg(l) + O2(g) 2HgO(s) ΔH°= -181kJΔS° = -67 J/K What is ΔG° at 50 °C?

  4. Calculate heat needed for: 230 g ice 230 g water at 0 °C at 30 °C

  5. Chem 140 Chap 10: Gases, Liquids, Solids Gases have little or no interactions, expand to fill space Liquids have significant interactions, defined volume, no defined shape. Solids have defined volume and shape. Gas Liquid Solid Shape: Volume: Interactions:

  6. Comparison of Gases Liquids and Solids Gases have little or no interactions, expand to fill space Liquids have significant interactions, defined volume, no defined shape. Solids have defined volume and shape. There are no forces (or very weak forces) holding gas molecules together, so they tend to fly apart. What holds liquid and solid molecules together? Gas Liquid Solid

  7. Intermolecular Forces Liquid and solid molecules are held together by intermolecular forces based on polarity. Polar molecules have an end that is partially positive (+) and an end that is partially negative (-). Since opposites attract, the partial positive on one molecule is attracted to the partial minus on a neighboring molecule.

  8. Polar Molecules - Bonds What makes a molecule polar? 1) and 2) Polar bonds – based on a concept called “electronegativity”, which is the ability of an atom to pull on electrons of a covalent bond.

  9. Electronegativity (EN or eleneg) 7.4 Electronegativity – the ability of an atom to attract electrons in a covalent bond. Examples – Hydrogen (H2) and HCl H–H or H:H Atoms pulls equally on electrons H–Cl or H:Cl Cl pulls more strongly on the two electrons of the covalent bond.

  10. Electronegativity – Periodic Properties Eleneg for elements on the periodic table show clear trends.

  11. Bond Polarity from Electronegativity To determine the polarity of a bond between two atoms, find the difference in electronegativity (EN) ΔEN = 0 to 0.4 bond is non-polar covalent ΔEN = .5 to 1.9 bond is polar covalent ΔEN > 2.0 bond in ionic These electronegativity differences are rough guidelines.

  12. Bond Polarity from Electronegativity ΔEN = 0 to 0.4 bond is non-polar covalent ΔEN = .5 to 1.9 bond is polar covalent ΔEN > 2.0 bond in ionic Find the difference in EN and classify the following bonds: C – H Li – O P – Cl EN: ΔEN:

  13. Polar Molecules - Shapes What makes a molecule polar? 1) Polar Bonds and 2) Unsymmetrical Shape Shape of Molecules – bases on the idea that electrons want to spread out and stay far away from each other. This theory is called “Valence Shell Electron Pair Repulsion” or VSEPR.

  14. VSEPR 7.9 VSEPR – based on the idea that atoms and lone pairs around a central atom will spread out as far as possible, due to the repulsion of the electron clouds. To determine geometry, count atoms + lone pairs (“charge clouds”) around the central atom. A t o m s + L o n e P a i r s : 2 3 4 Electron PairGeometry:

  15. EP Geometry and Shape of Molecules What is the electron pair geometry for the following molecules? (consider lone pairs AND atoms) What is the molecular shape? (consider only atoms) • a. NH3 b. CF4 c. H2O d. SO2 atoms +lone pairs

  16. Dipole Moments 01 Polar covalent bonds form between atoms of different electronegativity. A molecule has polar bonds that are unsymmetrical will be polar, and have a dipole moment.

  17. dipole moment Dipole Moments 03 Polarity can be illustrated with an electrostatic potential map. These show electron-rich groups as red and electron-poor groups as blue-green.

  18. Dipole Moments 04 These molecules are symmetrical, so dipole moment is zero.

  19. Dipole Moments 05 Which of the following compounds will have a dipole moment? Show the direction of each. • a. BH3 b. CF4 c. H2O d. SO2

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