INTERMOLECULAR FORCES AND SOLIDS & LIQUIDS - UNIT 07

EXTRA PROBLEMS FOR PRACTICE INTERMOLECULAR FORCES AND SOLIDS & LIQUIDS - UNIT 07 _________________________________________________________

Questions 1 through 23 are multiple choice questions. Questions 24 through 33 are free response.

1. Which compound is most likely to form intermolecular hydrogen bonds?

2. Which best explains why bromine is soluble in mineral oil?

3. The strongest interaction between hexane and iodine is . . .

4. In general, the strongest interaction with water molecules in aqueous solution are for ions that have . . .

5. Water and ethanol are completely miscible largely due to which intermolecular forces?

6. The energy absorbed when dry ice sublimes is required to overcome which type of interaction?

7. A container is half-filled with a liquid and sealed at room temperature and atmospheric pressure. What happens inside the container?

8. Acetone, (CH3)2C=O, is a volatile, flammable liquid. The central carbon is sp2 hybridized. The strongest intermolecular forces present in acetone are . . .

9. The molar masses of a series of similar polar molecules increases in this order: A < B < C < D < E. The boiling points, in degrees Celsius, of molecules A, B, C, D, and E are respectively, 20o, 50o, 150o, 100o, and 200o. Which molecule is likely to form hydrogen bonds?

(a) C4H10 (b) NaH (c) C2H5OH (d) C2H5SH (e) CH4

(a) Both substances are liquid. (b) Both substances have similar densities.

(c) Both substances are made of nonpolar molecules. (d) Both substances dissolve in water.

(e) One substance is made of polar molecules and the other is made of nonpolar molecules.

(a) covalent bonds (b) London dispersion (c) ionic bonds

(d) hydrogen bonds (e) ion-dipole attractions

(a) large charge and large size. (b) large charge and small size. (c) small charge and large size.

(d) small charge and small size. (e) zero charge and small size.

(a) covalent bonds (b) London dispersion (c) ionic bonds

(d) hydrogen bonds (e) ion-dipole attractions

(a) covalent bonds (b) ion-dipole forces (c) dipole-dipole forces

(d) dispersion forces (e) hydrogen bonds

(a) Evaporation stops.

(b) Evaporation continues for a time then stops.

(c) The pressure inside the container remains constant.

(d) The pressure inside the container increases for a time and then remains constant.

(e) The liquid evaporates until it is all in the vapor phase.

(a) dipole-dipole forces. (b) London dispersion forces. (c) hydrogen bonds.

(d) covalent bonds. (e) ion-dipole forces.

(a) A (b) B (c) C (d) D (e) E

Page of Revised 2018-2019 - from AP* Test Prep sources1 4


10. Which of the factors affect the vapor pressure of a liquid at equilibrium? I. Intermolecular forces of attractions within the liquid II. The volume and/or surface area of liquid present III. The temperature of the liquid

Questions 11 - 14 refer to the following information.

A solid is a poor conductor of electricity, is very hard, and has a high melting point. 11. The solid is probably . . .

12. The solid might be . . .

13. The solid could have the chemical formula . . .

14. The properties of this solid can be attributed to . . .

Examine the atomic-level structures of graphite and diamond to the right and answer Q 15-18. 15. The orbital hybridization of graphite and diamond,

respectively, are . . . (a) sp3 and sp3. (b) sp2 and sp2. (c) sp3 and sp2. (d) sp2 and sp3. (e) sp and sp2.

16. Which contains delocalized electrons.

17. Which conducts electricity?

(a) I only (b) II only (c) III only (d) I and II only (e) I and III only

(a) metallic. (b) an alloy. (c) ionic.

(d) molecular. (e) covalent network.

(a) quartz. (b) tin. (c) brass.

(d) table sugar. (e) rock salt.

(a) CaSO4. (b) Pb. (c) C20H42.

(d) SiC. (e) P2O5.

(a) an interlocking pattern of atoms. (b) intermolecular hydrogen bonding.

(c) the electron-sea model. (d) strong ion-ion interactions.

(e) interstitial atoms occupying the spaces between atoms.

(a) Neither graphite nor diamond. (b) Graphite only. (c) Diamond only.

(d) Both graphite and diamond. (e) There is not enough info.

(a) Neither graphite nor diamond. (b) Graphite only. (c) Diamond only.

(d) Both graphite and diamond. (e) There is not enough info.



18. Graphite is characterized by . . .

19. List the substances, CCl4, CBr4, and CH4 in order of increasing boiling point.

20. How do viscosity and surface tension change (a) as temperature increases and (b) and intermolecular forces of attraction become stronger? (a) Viscosity increases as IMFs increase while surface tension decreases. Both viscosity and surface tension increase

with increasing temperature. (b) Viscosity decreases as IMFs increase while surface tension increases. Both viscosity and surface tension increase

with decreasing temperature. (c) Both viscosity and surface tension increase as IMFs increase and temperature decreases. (d) Both viscosity and surface tension decrease as IMFs increase and temperature increases.

21. An important difference between crystalline solids and amorphous solids is that crystalline solids have . . .

22. In an interstitial alloy, the solute radii are ??? the solvent radii.

23. If a certain metal forms in a face centered cubic unit cell with an edge length of 3.52Å, what would you calculate as the radius of one atom?

24. Use concepts of chemical bonding and/or intermolecular forces to account for each of the following observations: a. The boiling points of water, ammonia, and methane are 100oC, -33oC, and -164oC, respectively. b. At 25oC and 1.0 atm, chlorine is a gas, bromine is a liquid, and iodine is a solid. c. Calcium oxide (2615oC) melts at a much higher temperature than does potassium chloride (770o). d. Propane is a gas and ethanol is a liquid, even though they have similar molar masses.

25. Answer the following questions about water using principles of solids, liquids, and gases and intermolecular forces. a. Why does water boil at a lower temperature in Denver, Colorado, than in New York City? b. For substances of similar molar mass, why does water have unusually high values for boiling point, heat of

vaporization, and surface tension? c. What structural features of ice cause it to float on water? d. Why does calcium chloride dissolve exothermically in water.

26. Use Coulomb’s law to qualitatively explain two reasons why hydrogen bonds, which are especially strong dipole-dipole forces of attraction, form only between hydrogen on one molecule and either nitrogen oxygen, or fluorine on another molecule.

27. Using some common laboratory equipment and materials, devise a plan to deduce the type of bonding in a sample of unknown solid. Specify the tests you would perform and discuss what the results mean.

28. (a) Draw an atomic representation of a binary ionic compound. Use the interactions of the particle to justify the structure and stability of the solid. (b) Use your model to explain these macroscopic properties of ionic solids:

i. melting point ii. conductivity iii. solubility

(c) Make a two-dimensional drawing of the solid showing at the atomic level why it is brittle.

(a) adjacent layers that can slide past each other. (b) London dispersions that hold the layers together.

(c) strong covalent bonds between the C atoms. (d) a high melting, relatively soft material.

(e) all of these.

(a) CH4 < CBr4 < CCl4 (b) CCl4 < CH4 < CBr4 (c) CH4 < CCl4 < CBr4 (d) CBr4 < CCl4 < CH4

(a) flat surfaces. (b) variables colors. (c) repeating lattice patterns. (d) low melting points.

(a) greater than (b) equal to (c) less than (d) sequestered by

(a) 4.60x10−8 cm (b) 4.98x10−8 cm (c) 8.80x10−9 cm (d) 1.24x10−8 cm



29. Draw a molecular depiction of the structure of ice. Label and name the major forces of attraction between the molecules and tell why these forces operate.

30. (a) Draw an atomic representation of a metal and describe the relative positions of atoms and electrons. (b) Use your depiction to explain on an atomic level the following macroscopic properties of metals:

i. electrical conductivity ii. malleability iii. high thermal conductivity

31. Draw a model of an interstitial alloy showing the relative positions of the atoms and the electrons. Explain the composition of a steel alloy and why it is harder and stronger than pure iron.

A Blast from the Past . . . 32. The two stable isotopes of chlorine have masses of 34.969amu and 36.966amu.

a. What are the mass numbers of the two isotopes of chlorine? b. Calculate the percent abundance of the lighter isotope. Hint: You know that Cl = 35.4527 amu. c. How many types of molecules with different masses exist in a sample of chlorine gas is the sample exists entirely as

diatomic molecules? Explain your answer. d. Calculate the mass of a single chlorine molecule (in grams) having the largest molecular mass. e. What is the mass (in amu and also in grams) of the most abundant molecule? Explain.

33. Like chlorine, iodine is a halogen and forms similar compounds. Write the names and formulas of the four oxyanions and the four oxyacids of iodine.


Documents

INTERMOLECULAR FORCES AND SOLIDS & LIQUIDS - UNIT 07