Honors Chemistry Name Chapter 10: Forces of Attraction, Phase Change, Date / / Period and Solids Answer Key Complete each of the following questions directly on this worksheet. Intermolecular and Intramolecular Forces 1. What is dipoledipole attraction? What is hydrogen bonding? 2. How do the strengths of dipoledipole forces compare with the strengths of ionic, polar covalent, covalent, and metallic bonds? 3. Explain how London dispersion forces arise. Although London dispersion forces exist among all molecules, for what type of molecules are they the only major intermolecular forces? Are London dispersion forces relatively strong or relatively weak? Explain. 4. How do intermolecular forces affect each of the following? a. When intermolecular forces increase the boiling point. b. When intermolecular forces increase the melting point. c. When intermolecular forces increase vapor pressure. d. Solubility e. Adhesive force f. Cohesive forces 5. What causes dipoledipole interactions? a. unequally sharing of electron pairs b. bonding of a covalentlybonded hydrogen to an lone electron pair c. the random motion of electrons d. none of these 6. Why is hydrogen bonding only possible with hydrogen? a. Hydrogen is the least electronegative element known. b. The size of a hydrogen atom is similar to that of oxygen, nitrogen, and fluorine. c. Hydrogen is the only atom with an unshielded nucleus when it forms covalent bonds.
d. More than one of the above. 7. Which of the following has the least amount of attractive force? a. polar covalent bond b. hydrogen bond c. ionic bond d. dipoledipole force 8. What is the strongest force of attraction present for each of the following compounds? Drawing the geometric structures can help to determine the type of attraction for some of the substances. a. water b. carbon tetrachloride c. ammonia d. carbon dioxide e. phosphorus trichloride f. nitrogen molecule g. ethane (C 2 H 6 ) h. acetone (CH 3 COCH 3 ) i. methanol (CH 3 OH) j. borane (BH 3 ) 9. Circle all the compounds in the following list that would be expected to form intermolecular hydrogen bonds in the liquid state. Drawing the geometric structures can help to determine the type of intermolecular forces. The underlined element is the central atom. a. CH 3 OCH 3 (dimethyl ether) c. HF e. Br 2 b. CH 4 d. CH 3 CO 2 H (acetic acid) f. CH 3 OH (methanol) 10. Specify the predominant force of attraction involved for each substance in the space immediately following the substance. Then in the last column, indicate which member of the pair you would expect to have the higher boiling point. Substance #1 Predominant Force of Attraction Substance #2 Predominant Force of Attraction Substance with Higher Boiling Point a. HCl (g) I 2 b. CH 3 F CH 3 OH c. H 2 O H 2 S d. SiO 2 SO 2 e. Fe Kr f. CH 3 OH CuO g. NH 3 CH 4 h. HCl (g) NaCl i. SiC Cu
11. What type of forces must be overcome to melt or vaporize a substance (are these forces intramolecular of intermolecular)? Explain. 12. Define the equilibrium vapor pressure of a liquid. How is the magnitude of a liquid s vapor pressure related to the intermolecular forces? 13. How do we know that the properties of the solid and the liquid states of a substance are more similar than to the properties of the substance in the gaseous state? 14. Explain how the process of vaporization and condensation represent equilibrium in a closed container. 15. What is surface tension? What is the effect of a dishwashing liquid on the surface tension of water? Explain.
For each of the questions on this worksheet, refer to the phase diagram for mysterious compound X. 16. What is the critical temperature of compound X? 17. If you were to have a bottle containing compound X in your closet, what phase would it most likely be in? 18. At what temperature and pressure will all three phases coexist? 19. If I have a bottle of compound X at a pressure of 45 atm and temperature of 100 o C, what will happen if I raise the temperature to 400 o C? 20. Why can t compound X be boiled at a temperature of 200 o C? 21. If I wanted to, could I drink compound X? 22. What observable difference would there be for the solid/liquid line for the phase diagram for compound X and the phase diagram for water? Why? Refer to your notes/book for a phase diagram of water. 23. What is vaporization? What is condensation? 24. Define molar heat of fusion and molar heat of vaporization.
25. The heat of fusion of aluminum is 3.95 kj/g. What is the molar heat of fusion of aluminum? 26. Calculate the total energy required to convert 55.1 grams of ice at 0.00 o C to a resulting gaseous state at 100. o C. S (solid) = 2.1 J/g o C H fusion = 6.02 kj/mole S (liquid) = 4.2 J/g o C H vaporization = 40.7 kj/mole S (vapor) = 2.1 J/g o C 27. Draw a heating / cooling curve for iron, which has a melting point of 1535 o C and a boiling point of 2750 o C. Make sure to properly label both axis of your graph.
Types of Solids 28. Crystalline solid 29. List the properties of each of the following? a. Ionic solids b. Molecular solids c. Atomic solids Network Atoms Metals Noble gases
d. Alloy substitutional alloy Interstitial alloy