p424 Chapter Ten: Liquids and Solids

Transcription

1 p424 Chapter Ten: Liquids and Solids

2 Contents p424

3 0 H 2O( s) H 2O( l) H fus 6.02 kj / mol 0 H 2O( l) H 2O( g) H vap 40.7 kj / mol p426

4 p Intermolecular Forces Dipole-Dipole Forces 4

5 Hydrogen Bonding in Water. To distinguish betweenp427 intramolecular bonds and intermolecular forces. 5

6 Dipole-Dipole Forces 6

7 Hydrogen Bonding 7

8 p427 Figure 10.4 The Boiling Points of the Covalent Hydrides of the Elements in Groups 4A, 5A, 6A, and 7A.

9 London Dispersion Forces p428 9

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11 Table 10.2 The Freezing Points of the Group 8A Elements p428 11

12 10-2 The liquid state p429

13 p430 Beads of water on a waxed car finish. The nonpolar component of the wax causes the water to form approximately spherical droplets.

14 React As intermolecular forces increase, what happens to each of the following? Why? Boiling point Viscosity Surface tension Enthalpy of fusion Freezing point Vapor pressure Heat of vaporization

15 10-3 An Introduction to Structures and Types of Solids p430 Amorphous Solids Disorder in the structures Glass Crystalline Solids Ordered Structures Unit Cells 15

16 p432 Figure 10.9 Three cubic unit cells and the corresponding lattices. Note that only parts of spheres on the corners and faces of the unit cells reside inside the unit cell, as shown by the cutoff versions.

17 X-Ray Analysis of Solids p433 Figure X rays scattered from two different atoms may reinforce (constructive) or cancel (destructive interference) one another. (a) Both the incident rays and the reflected rays are also in phase. In this case, d 1 is such that the difference in the distances traveled by the two rays is a whole number of wavelengths. (b) The incident rays are in phase but the reflected rays are out of phase. In this case d 2 is such that the difference in distances traveled by the two rays is an odd number of half wavelengths.

18 P433 Ex 10.1 Using the Bragg Equation X rays of wavelength 1.54 were used to analyze an aluminum crystal. Assuming n = 1, calculate the distance d between the planes of atoms producing this reflection. Solution: To determine the distance between the planes, 2d sin n n (1)(154 pm) d 233 pm 2sin (2)(0.3305) 18

19 Types of Crystalline Solids p435 Figure Examples of Three Types of Crystalline Solids. (a) An atomic solid. (b) An ionic solid. (c) A molecular solid. The dotted lines show the hydrogen bonding interactions among the polar water molecules.

20 Table 10.3 Classification of Solids p436

21 10-4 Structure and Bonding in Metals p437 Figure The closest packing arrangement of uniform spheres.

22 Hexagonal Closest Packing p437 Figure When spheres are closed packed so that the spheres in the third layer are directly over those in the first layer (aba), thee nit cell is the hexagonal prism illustrated here in red.

23 Cubic Closest Packing Figure When spheres are packed in the abc arrangement, the unit cell is face-centered cubic. To make the cubic arrangement easier to see, the 23 vertical axis has been tilted as shown.

24 The indicated sphere has 12 nearest neighbors p439 Figure

25 p439 Figure The net number of spheres in a facecentered cubic unit cell. The net number of spheres in a face-centered cubic unit cell is 1 1 ( 8 ) (6 ) 4 8 2

26 Ex 10.2 Calculating the Density of a Closest Packed Solid P439 Silver crystallizes in a cubic closest packed structure. The radius of a silver atom is 144 pm. Calculate the density of solid silver. 26

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28 Bonding Models for Metals P440 Electron sea model Band model (MO model) 28

29 The Electron Sea Model p441 Figure The electron sea model for metals postulates a regular array of cations in a sea of valence electrons.

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31 The Band Model for Magnesium p442 Figure (left) A representation of the energy levels (bands) in magnesium crystal. The electrons in the 1s, 2s, and2p orbitals are close to the nuclei and thus localized on each magnesium atom as shown. However, the 3s and 3p valence orbitals overlap and mix to form molecular orbitals. Electrons in these energy levels can travel throughout the crystal. (right) Crystal of magnesium grown from a vapor.

32 Metal Alloys p444 Substitutional Alloy Interstitial Alloy

33 10-5 Carbon and Silicon: Network Atomic Solids p444 Network solids Figure The structures of diamond and graphite. In each case only a small part of the entire structure is shown.

34 Network Solids 34

35 p445 Figure Partial representation of the molecular orbital energies in (a) diamond and (b) a typical metal.

36 The p Orbitals p445 Figure The p orbitals (a) perpendicular to the plane of the carbon ring system in the graphite can combine to form (b) an extensive π-bonding network. 36

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42 Table 10.5 Compositions of some common types of glass p448

43 Ceramics p448

44 Semiconductors p450 Silicon Crystal Doped with (a) Arsenic and (b) Boron.

45 Figure Energy level diagrams for (a) an n-type semiconductor and (b) a p-type semiconductor. p450

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47 Magnetic Levitation By a Superconductor 47

48 10-6 Molecular Solids p454

49 10-7 Ionic Solids p457

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51 Ex 10.3 Determining the Number of Ions in a Unit Cell Determining the number of Na + and Cl - ions in the sodium chloride unit cell. P457 Figure 10.37

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53 Molecular Solids 53

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55 Ionic Solids 55

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57 Ex 10.4 Types of Solids Using Table classify each of the following p459 substance according to the type of solid it forms.

58 10.8 Vapor Pressure and Changes of State p459 Vaporization or evaporation Heat of vaporization The enthalpy of vaporization is symbolized as The rate of condensation The rate of evaporation Highly dynamic on the molecular level Figure Behavior of a liquid in a closed container. 58

59 The Rates of Condensation and Evaporation p460 Figure The rate of condensation over time for a liquid sealed in a closed container. The rate of evaporation remains constant and rate of the increases as the number of molecules in the vapor phase increases, until the two rates become equal. At this point, the equilibrium vapor pressure is attained..

60 Vapor Pressure p460

61 Vapor Pressure vs. Temperature p462 Figure 10.42

62 p461 H ln( p vap ) H vap 1 ln( p vap ) ( ) C 10.4 R T Figure (b)

63 Ex 10.5 Determining Enthalpies of Vaporization Using the plots in Fig (b), determine whether water or diethyl ether has the larger enthalpy of vaporization. P461

64 P463 EX 10.6 Calculating Vapor Pressure The vapor pressure of water at 25 is 23.8 torr, and the heat of vaporization of water at 25 is Calculate the vapor pressure of kj / mole water at 50.

65 Solution: p463

66 Changes of State p464 Figure Heating curve for (not drawn to scale) for a given quantity of water energy water is added at a constant rate. The plateau at the boiling point is longer than the plateau at melting point because it takes almost seven times more energy (and thus seven times the heating time) to vaporize liquid water than to melt ice. The slopes of the other lined are different because the different states of water have different molar heat capacities (the energy required to raise the temperate of 1 mol of substance by 1 ).

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69 Boiling Water with Ice 69

70 Changes of State 70

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73 10-9 Phase Diagrams p467 73

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77 React Explain the differences in the phase diagrams of water and carbon dioxide. 77

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