IMF’s, Solids, and Liquids

1. IMF’s, Solids, and Liquids Ch. 11 in Textbook msconti.blogspot.com

2. I. Intermolecular Forces (IMF’s) • attractions between separate molecules, not bonds • relatively weak • occur based on molecular polarity and/or charge • the strength determines substance’s phase, b.p., m.p., vapor pressure, etc. itl.chem.ufl.edu HW: 11.4, 11.6

3. science.uwaterloo.ca

4. 1. Ion-Dipole Forces (AKA Molecule-Ion Attractions) • between an ion (full charge) and the δ+ or δ- of a polar molecule • usually the polar molecule is water acting as a solvent • the greater the magnitude of the ionic charge and/or the partial charges, the stronger the IMF’s chem.purdue.edu

5. chemprofessor.com

6. van der Waals ForcesA) Dipole-Dipole Forces • a dipole (2 poles) is a polar molecule • attractions between polar molecules • relatively strong, but technically weaker than ion-dipole forces • the higher the value of μ (dipole moment), the higher the IMF’s (for similar mass/size molecules) chemtext.blogspot.com

7. chem.unsw.edu.au

8. B) Hydrogen Bonding • NOT a bond • when H is bonded to very EN elements (N,O,F, ONLY) a “super dipole” is formed • usually NH3, H2O, and HF • this leads to unusually high dipole-dipole attractions and thus, unusually high b.p.’s • also results in ice being less dense than water • weren’t you listening, I said it’s “NOT a bond!” chemed.chem.wisc.edu

9. yellowtang.org

10. C) London Dispersion Forces (AKA Weak Forces) • occurs between nonpolar molecules • helps when molecules are close to one another • results from momentary/temporary/ induced dipoles itl.chem.ufl.edu

11. the more you can distort an atom or molecule’s electron cloud distribution, the more polarizable it is • larger/massive atoms/molecules are more polarizable • thus, larger atoms/molecules have stronger IMF’s • ex) halogens elmhurst.edu

12. C cactus.dixie.edu

13. NOTE: all molecules have London dispersion forces! • when molecules are of similar size, polarity determines the strength of IMF’s • when molecules differ greatly in size, then polarizability determines the strength of IMF’s phys.bspu.unibel.by HW: 11.8, 11.10, 11.12 (a)-(c), 11.18, 11.22

14. IMF flow chart • do activity in lab area as a group of 4 • have chart “Schu approved” • copy as notes adroll.com

15. Properties of Liquids1. Viscosity • resistance to flow • high viscosity- molasses, syrup • low viscosity- ethanol, water • based not only on the strength of the IMF’s, but also structural features that may cause entanglement of molecules • as temp. inc., viscosity dec. due to the breaking of IMF’s syntheticperformanceoil.com

16. 2. Surface Tension • due to the imbalance of IMF’s within a liquid • there is a net downward pull of surface molecules • results in close packing of molecules at the surface, forming a “skin” fizyka.phys.put.poznan.pl

17. technically, surface tension is defined as the energy required to increase the surface area of a liquid by a unit amount • units: J/m2 quest.nasa.gov

18. water has a high surface tension due to high IMF’s • mercury has an even higher surface tension due to metallic bonding ramehart.com HW: 11.23

19. 3. Cohesion and Adhesion • cohesion = IMF’s between molecules of the same substance • adhesion = IMF’s between molecules and other surface • although both types of forces are present, mercury has greater cohesive forces than water whereas water has greater adhesive forces than mercury cr4.globalspec.com

20. 4. Capillary Action • molecules of liquid rising up a narrow tube • mechanism = adhesion causes water to stick to tube which increases the surface area; in order to reduce surface area, surface tension pushes water up tube against gravity • ex) chromatography; water in plant roots cc.gatech.edu HW: 11.24

21. III. Phase Changes chemistry.wustl.edu HW: 11.28

22. 1. Heating/Cooling Curves physicalweeding.com

23. heat is ALWAYS being added! • when temperature increases, the KE (energy of motion) of the particles must be increasing (PE remains the same) • when temperature remains the same, the KE of the particles must remain the same; thus, PE (energy of position) increases as the phase change occurs funsci.com

24. ΔHvap > ΔHfus • q = mCΔT used for calculating heat during temp. changes • where q = heat change in J m = mass in g C = specific heat in J/g·K or J/g·ºC ΔT = temp change (Tf – Ti) in K or ºC mrbigler.com HW: 11.34

25. 2. Vapor and Vapor Pressure • vapor = gaseous form of a substance normally found as a liquid • vapor pressure = pressure due to vapor • evaporation = vaporization of surface molecules of liquid • boiling = vaporization throughout liquid, occurs when the vapor pressure = atmospheric pressure kidsgeo.com

26. STORYTIME! cityoflawton.ok.us

27. #1 Water in a Beaker • @ room temp and standard pressure • what happens to it? goldcoast.qld.gov.au

28. #2 Stoppered Flask of Water • @ room temp and standard pressure • what happens to it? daigger.com

29. #3 Ethanol Vs. Water • @ room temp and standard pressure • what happens? • volatility = the ability to evaporate easily outboardmotoroilblog.com images.veer.com

30. #4 Heated flask of Water • constant heating @ standard pressure • what happens to it? • normal boiling point = temperature at which the v.p. of water equals 1 atm (standard pressure) demo.physics.uiuc.edu HW: 11.39, 11.42

31. 3. Vapor Pressure Curves kentchemistry.com HW: 11.43

32. Phase Diagrams from textbook

33. triple point = temp. and pressure at which all 3 phases exist in equilibrium • critical point = the highest temp. and pressure at which a liquid can exist • supercritical fluid = liquid and gas phases are indistinguishable definitiontees.com HW: 11.36, 11.47, 11.48, 11.50, 11.52

34. Structures of Solids1. Crystalline vs. Amorphous • crystalline = well-defined arrangement of atoms or molecules (def. attractions = def. m.p.) • ex) quartz, diamond, ionic solids • amorphous = no well-defined arrangement of atoms or molecules (indef. attractions = softens over temp. range, no distinct m.p.) • ex) glass, rubber ndt-ed.org HW: 11.53

35. 2. Unit Cells • unit cell = the “bricks” that make up a crystalline solid; the smallest repeating unit in a crystal lattice fkp.jku.at

36. A) Primitive Cubic • the lattice points are at the corners and are actually shared by 8 atoms! • 1/8 of an atom x 8 corners = 1 atom ece-www.colorado.edu mrsec.wisc.edu

37. B) Body-Centered Cubic • lattice points are at the corners and at the center • 1/8 of an atom x 8 corners + 1 atom = 2 atoms ece-www.colorado.edu mrsec.wisc.edu

38. C) Face-Centered Cubic • lattice points are at the corners and each face/side • ½ of an atom x 6 sides + 1/8 atom x 8 corners = 4 atoms ece-www.colorado.edu HW: 11.56, 11.58 mrsec.wisc.edu

39. 3. Bonding in Solids • molecular solids • ionic solids • metallic solids • covalent-network solids = continuous lattice structure of covalent bonds (no molecules); rigid and dense with high m.p.’s (FYI, must break bonds to melt!) • ex) SiO2, C (diamond), C (graphite), C (buckyballs) chem.ufl.edu HW: 11.69, 11.70

40. legacy.co.mohave.az.us