Chapter 10 Review Packet Name 1. If water and carbon dioxide molecules did interact, what major intermolecular force will exist between these molecules? a) Hydrogen bonding b) London dispersion c) Dipole-dipole forces 2. Which of the following molecule pairs are not involved in hydrogen bonding? a) HCOOH, H 2 O b) H 2 O, NH 3 c) CH 3 OH, CH 3 COOH d) H 2 and I 2 3. Arrange the following molecules in order of decreasing intermolecular interaction: SO 2, Cl 2, CH 3 OH, CH 3 NH 2 a) CH 3 OH > CH 3 NH 2 > SO 2 > Cl 2 b) Cl 2 > SO 2 > CH 3 OH > CH 3 NH 2 c) SO 2 > CH 3 NH 2 > CH 3 OH > Cl 2 d) CH 3 NH 2 > CH 3 OH > SO 2 > Cl 2 4. Knowing that solutes with a certain polarity (or absence of it) are best dissolved in solutions with similar polarity, which of the following solvents would be optimal for the solvation of CH 3 COOH? a) CH 4 b) CH 3 OH c) C 2 H 6 d) C 6 H 6 5. Which of the following molecules interact primarily through London-dispersion forces? a) SO 2 b) CCl 4 c) CH 2 Cl 2 d) H 2 S 6. Which of the following has the highest boiling point? a) H 2 O b) HF c) HI d) HBr
7. Surface tension is due to the: a) liquid molecules being more attracted to surrounding surface molecules than other liquid molecules b) liquid molecules being as attracted to surrounding molecules as to other liquid molecules c) liquid molecules being more attracted to other liquid molecules than surrounding molecules d) liquid molecules being attracted only to surrounding molecules 8. Which of the following liquids will be the most viscous? a) C 3 H 8 b) C 6 H 6 c) CH 4 d) C 2 H 6 9. In the liquid state, molecules: a) are100% hydrogen bonded to their neighbors. b) are part of a crystal lattice. c) are frozen in space. d) are considerably restricted in movement. 10. Which of the following liquids would show a convex meniscus when placed in a glass tube? a) CH 3 OH(l) b) H 2 O(l) c) CHCl 3 (l) d) BF 3 (l) 11. The smallest repeating unit of the lattice is called: a) unit cell b) unit lattice c) cell d) unit crystal 12. Which of the following types of solids exist as crystals? a) ionic solids b) atomic solids c) molecular solids d) metallic solids 13. The successive packing pattern for an hcp cell is which one of the following? a) ABABAB b) ABAABA c) ABCABC d) ABCCBA
14. X-rays with a particular wavelength were used to analyze a crystalline solid. Assuming n = 1, and knowing that the distance between the planes of atoms, producing a diffraction with an angle = 20.0º, is 200 pm, calculate the frequency of the X-rays. a) 365 b) 6.22 x 10 15 c) 0.110 d) 2.19 x 10 18 15. Conducting electrons in metals are situated in: a) Localized orbitals b) s-orbitals c) Metallic orbitals d) Conduction bands 16. The vapor pressure of 1-propanol at 14.7 C is 10.0 torr. The heat of vaporization is 47.2 kj/mol. Calculate the vapor pressure of 1-propanol at 52.8 C. a) 100. torr b) 20.0 torr c) 200. torr d) 600. torr ln P T1 = ΔH vap 1 1 P T2 R T 2 T 1 ln 10.0 = 47,200 J/mol 1 1 P T2 8.3145 J/mol 326.0 K 287.9 K ln(10/p T2 ) = 2.304 10/P T2 = 0.0999 P T2 = 100. torr
17. The difference between interstitial alloy and substitutional allow is that in substitutional alloys: a) Some atoms of one element are replaced by atoms of another element b) Atoms of one element are inserted in the spaces between the atoms of the other element c) Atoms of one element fuse with the atoms of the other element d) Three elements, rather than two, are combined to form the alloy 18. Which one of the following decreases as the strength of the attractive intermolecular forces increases? a) The heat of vaporization. b) The normal boiling temperature. c) The extent of deviations from the ideal gas law. d) The sublimation temperature of a solid. e) The vapor pressure of a liquid. 19. Which one of the following statements about liquids and solids is generally false? a) The rate of diffusion is lower in solids. b) The density of solids is higher. c) The compressibility of liquids is higher. d) Liquids have higher vapor pressures. e) The heat of vaporization is less than the heat of fusion. 20. Which of the following is a correct listing in terms of increasing boiling point? a) CH 4 < NH 3 < H 2 O < HF b) CH 4 < NH 3 < HF < H 2 O c) CH 4 < HF < NH 3 < H 2 O d) HF< H 2 O < NH 3 < CH 4 e) CH 4 < HF < H 2 O < NH 3 21. The boiling points of the halogens increase from F 2 to I 2. What type of intermolecular forces are responsible for this trend? a) permanent dipole b) hydrogen bonding c) ion-ion attraction d) London dispersion forces e) ion-dipole attraction 22. Which of the following statements is true about p-type silicon? a) It is produced by doping Si with P or As. b) Electrons are the mobile charge carriers. c) It does not conduct electricity as well as pure Si. d) All are true. e) None is true. As atomic size increases, LD forces become increasingly more important. a. is incorrect because it produces an n-type semiconductor. b. is incorrect because the charge carriers are holes in a p-type. c. is incorrect because it would conduct better than pure Si.
23. Doping Se with As would produce a(n) semiconductor with conductivity compared to pure Se. a) n-type, increased b) n-type, decreased c) p-type, increased d) p-type, decreased e) intrinsic, identical 24. A material is made from Al, Ga, and As. The mole fraction of each element is 0.25, 0.26, and 0.49, respectively. This material would be a) a metallic conductor because Al is present. b) an insulator. c) a p-type semiconductor. d) an n-type semiconductor. e) none of the above 25. Which of the following statements about superconductors is false? a) They conduct electricity without wasting heat energy. b) A class of high-temperature superconductors is called perovskites. c) Good conductivity, efficiency, and ductility are reasons why ceramic materials are used in superconductors. Ceramics are brittle, not ductile. d) High-temperature superconductors contain copper, oxygen, a lanthanide metal, and an alkaline earth metal. e) All of these are true. 26. Which of the following statements about phase changes are true? I. No temperature change is observed during a phase change. II. Vaporization is an exothermic process. EXOTHERMIC III. When a phase change occurs, no energy is transferred to or from the substance. IT TAKES ENERGY TO BREAK IMF S!! IV. When cooling a given amount of a substance, the rate at which cooling occurs is a function of.the mass of the substance and its specific heat. V. The heat of fusion for ice would determine how much energy would be required to change the temperature of a 10-g block of ice from 20 C to 2 C. IT WOULD BE NECESSARY TO KNOW THE SPECIFIC HEAT OF ICE, NOT THE HEAT OF FUSION! a) I and III b) I and IV c) II and III d) II, III, and IV e) IV only As has one less valence electron than Se so the resulting semiconductor would be a p-type. This would increase the conductivity due to holes that the electrons can jump into. Twice as much As would seem that the material was doped with Al and Ga. Because Al and Ga have fewer valence electrons than As, it would make this a p-type.
For questions 27 and 28, use the phase diagram for compound X below: 27. The normal boiling point of X is most likely: a) 21 C b) 47 C c) 73 C d) 18 C e) 0 C 28. How will the melting point of X change with increased pressure? a) increase b) decrease c) remain the same d) there is not enough information given e) increase and then decrease 29. How much energy is needed to convert 64.0 grams of ice at 0.00 C to water at 75.0 C? specific heat capacity of water = 4.18 J/g C H vap of water = 2258 J/g specific heat capacity of ice = 2.1 J/g C H fusion of water = 333 J/g a) 10.1 kj b) 20.7 kj c) 31.4 kj d) 41.4 kj e) 65.8 kj Melt water. q = ΔH fus grams q = (333 J/g) (64.0 g) q = 21,300 J = 21.3 kj Heat water from 0 C to 75 C. q = mcδt q = (64.0 g) (4.18 J/g C) (75 C 0 C)) q = 20,100 J = 20.1 kj Add to get the energy needed: 21.3 kj + 20.1 kj = 41.4 kj
30. Which of the compounds below is an example of a network solid? a) S 8 (s) b) SiO 2 (s) c) MgO (s) d) NaCl (s) e) C 25 H 52 (s) 31. How much heat is required to change the temperature of a 10.0-gram ice cube from 15 C to 132 C?
32. Use the band model to describe differences between insulators and conductors. The band model or molecular orbital (MO) model for metals is a molecular model for metals in which the electrons are assumed to travel around the metal crystal in molecular orbitals formed from the valence atomic orbitals of the metal atoms. In this model, the electrons are assumed to travel around the metal crystal in molecular orbitals formed from the valence atomic orbitals of the metal atoms. When many metal atoms interact, as in a metal crystal, the large number of resulting molecular orbitals become more closely spaced and finally form a virtual continuum of levels, called bands. This existence of empty molecular orbitals close in energy to filled molecular orbitals explains the thermal and electrical conductivity of metal crystals. Metals conduct electricity and heat very efficiently because of the availability of highly mobile electrons. The difference between insulators and conductors comes in the proximity of the molecular orbitals. Metals have MO's that are very close together. The band model is used to explain heat and electrical conduction. In this model, mobile electrons are furnished when electrons in filled molecular orbitals are excited into empty ones. These conduction electrons are free to travel throughout the metal crystal. Nonmetals have a wide gap between its MO's. As a result, their electrons cannot be excited into empty MO's. Therefore, they do not conduct heat and electricity in an appreciable manner. 33. How can an n-type semiconductor be produced from pure germanium? Explain. To produce an n-type semiconductor, dope Ge with a substance that has more than 4 valence electrons, (a group 15 element). Phosphorus or arsenic are a couple of substances which would produce n-type semiconductors when they are doped into germanium. 34. What would be the shape of the meniscus of water in a polyethylene tube? (Polyethylene can be represented as CH 3 (CH 2 ) n CH 3, where n is a large number on the order of 1000.) Justify your answer. Polyethylene is a nonpolar substance. The H 2 O-H 2 O attraction (cohesive force) is stronger than the H 2 O-polyethylene attraction (adhesive force) because of hydrogen bonding in the former and only LDF in the latter. Thus, the meniscus will have a convex shape.
35. How much heat is given off when 164 g of steam at 350. C is cooled to ice at 125 C. 9.11 mol H 2 O
36. Order the following compounds from largest to smallest enthalpy of fusions: H 2 O, CO 2, MgO (Justify your answer!) H 2 O has hydrogen bonding as well as dipole and LDF. CO 2 has is nonpolar and has only LDF. MgO is ionic. Ionic is the strongest force, then hydrogen bonding, and finally LDF. Thus the order of largest to smallest forces will be MgO, H 2 O, and CO 2. As intermolecular forces decrease, the enthalpy of fusions decrease. Therefore, the order from largest to smallest enthalpy of fusions: MgO, H 2 O, CO 2 37. How much heat is necessary to melt 175.32 g of sodium chloride at 801 C? (The heat of fusion of sodium chloride is 28.16 kj/mole.) 28.16 kj 1 mol NaCl 175.32 g NaCl = 84.476 kj 1 mol NaCl 58.443 g NaCl Remember: *As IMF's increase, all properties (b.p., m.p., viscosity,...) will also increase EXCEPT vapor pressure which will decrease. *Know how to determine LDF, dipole-dipole, and H-bonding. *LDF's become more important as the SIZE of the atom increases. *Understand cohesive and adhesive forces which produce either a convex meniscus or a concave meniscus. *Know that "normal" means at 1 atmosphere of pressure and 1 atm = 760 mm Hg = 101.3 kpa *Know that "standard pressure" = 1 atm *Understand the trends in the diagrams of the alkanes and the b.p. s of the hydrogen compounds of Groups 14-17. *Understand phase diagrams and how to read them. *Understand the trend that density follows during phase changes. *Know the difference between substitutional and interstitial alloys and examples of each. *Know the difference between n-type and p-type semiconductors and how to form each. *Know how to calculate enthalpy changes (Like a 10.0-g ice cube at 15 C to 150. C) *Understand the band model pertaining to thermal and electrical conductivity of metals.