Subject: Chemistry    / General Chemistry
Question

Review Questions:

Multiple-Choice:

1. Substances that are liquids at room temperature or below are

A. ionic.

B. nonpolar covalent molecular.

C. metallic.

D. covalent network.

2. Crystals such as diamonds (very hard, high melting point, nonconductors) are classified as

A. ionic crystals.

B. covalent molecular crystals.

C. covalent network crystals.

D. metallic crystals.

3. Metallic crystals characteristically have

A. good electric conductivity.

B. great hardness.

C. low melting points.

D. brittleness.

4. Because of the hydrogen bonds in water, the hydrogen atom of one water molecule may be

A. weakly attracted to the oxygen of a second water molecule.

B. weakly attracted to the hydrogen of a second water molecule.

C. strongly attracted to the second hydrogen of its own molecule.

D. strongly attracted to the oxygen of a second water molecule.

5. As ice is heated from a lower temperature towards its melting point, the hydrogen bonds

A. get stronger.

B. stretch.

C. increase in number.

D. cause the formation of hexagonal patterns.

6. What is thought to cause dispersion forces?

A. attraction between ions

B. motion of electrons

C. differences in electronegativity

D. the formation of hexagonal patterns

7. Why is hydrogen bonding only possible with hydrogen?

A. because hydrogen is the only atom whose nucleus is not shielded by electrons when it is involved in a covalent bond

B. because hydrogen is the only atom that is the same size as an oxygen atom

C. because hydrogen has the highest electronegativity of any element in the periodic table

8. What is the basis of a metallic bond?

A. the attraction of metal ions for mobile electrons

B. the attraction between neutral metal atoms

C. the neutralization of protons by electrons

D. the attraction of oppositely charged ions

9. What occurs during the dissolving of an ionic crystal?

A. Ions separate from molecules.

B. Molecules surround ions.

C. Molecules bind covalently to molecules.

D. Ionic compounds are formed.

10. Why are two nonpolar substances able to dissolve each other?

A. There is no repulsive force between them.

B. They combine to produce a polar substance.

C. There is no attractive force between them.

D. Nonpolar molecules cannot dissolve in each other.

11. Chlorine is a gas, bromine is a liquid, and iodine a solid because of differences in the strength of their

A. hydrogen bonds.

B. dispersion forces.

C. dipole interactions.

D. polar bonds.

12. The high surface tension of water is due to the

A. small size of water molecules.

B. high kinetic energy of water molecules.

C. hydrogen bonding between water molecules.

D. covalent bonds in water molecules.

13. It has been said, “There are forces of attraction between molecules in all chemical systems.” Which of the following experimental observations supports this statement?

A. Gases can be condensed to form liquids.

B. Solids are very difficult to compress.

C. Liquids have an indefinite shape.

D. Not all solids are ionic crystals.

14. Ionic solids

A. are soft and have low melting points.

B. melt to form liquids that conduct electricity.

C. are malleable.

D. conduct electricity.

15. Solid sodium metal and molten sodium chloride conduct electricity because both contain

A. mobile electrons.

B. mobile ions.

C. active metals, which are good conductors.

D. mobile charged particles.

For questions #16 to 26, write the letter of the bond or attractive force, chosen from the list below, that is most closely associated with that compound or phrase.

A. ionic bond

B. network covalent bonds

C. dipole-dipole attractions

D. hydrogen bonds

E. metallic bond

F. covalent bonds

G. dispersion forces

16. Are weak enough to permit solid iodine to sublime readily upon heating.

17. Al(s)

18. Bond noble gas atoms in the liquid phase.

19. Responsible for the extremely high melting point of diamond (above 3500º C).

20. Link the atoms in a molecule of a diatomic gaseous element.

21. Allows methanol to be infinitely soluble in ethanol.

22. SiO2(s)

23. Positive ions immersed in a “sea of mobile (delocalized) electrons.”

24. This substance will not conduct as a solid, but will conduct as a liquid or in solution.

25. .png”>OCl2

26. (diagram)

27. Which of the following processes requires the least energy?

A. Breaking the bond between Na+ and Cl? in NaCl.

B. Breaking the bond between H and Cl in HCl.

C. Separating two CO molecules.

D. Separating two H2O molecules.

28. Which of the following transformations is sublimation?

A. Solid® Gas

B. Gas® Solid

C. Liquid® Solid

D. Solid® Liquid

29. Using intermolecular force theory, explain why a substance will change from a gas to a liquid if the temperature is lowered sufficiently.

30. Explain the difference in boiling points of C2H5Cl (bp = 13ºC) and C4H10 (bp = ?0.5ºC).

31. Account for the difference in boiling points of F2 (bp = ?188ºC) and C2H6 (bp= ?87ºC).

32. List the intermolecular bonding forces present in ethanol, C2H5OH.

Consider the following substances C2H3Cl and C2H3I when answering the next three questions.

33. Which of the substances, C2H3Cl and C2H3I, would probably be more polar? Explain.

34. Which would probably have the higher boiling point? Explain.

35. What specific type of bonding probably contributes most to the intermolecular attractions in these substances? Explain your answer.

36. Unit K – Organic Chemistry will provide information about the molecular compound benzene, C6H6(l). The boiling points for some benzene derivative compounds are:

C6H5F(l) : 85ºC C6H5Cl(l) : 132ºC C6H5I(l) : 188ºC

Which of the following is most probably the boiling point for C6H5Br(l)? How can you tell?

98ºC 122ºC 156ºC 249ºC 337ºC

37. Phenol, C6H5OH(s) (182ºC), has a boiling point very close to that of iodobenzene, C6H5I(l) (188ºC). List the bond types contributing to the intermolecular attractions in each substance. Explain why the boiling points are so similar.

38. Benzoic acid, C6H5COOH, has the structure shown below. Can a confident prediction be made as to whether its boiling point will be greater or less than that of phenol? Explain.

H H

.png”>         .png”>

.png”>.png”>.png”>.png”> C == C O

.png”>.png”>.png”>.png”> H –– C C –– C

.png”>

.png”>.png”> C –– C O –– H

H H

39. Given that phenol melts at 43ºC, what would be the most likely physical state of benzoic acid at room temperature? Explain.

40. Arrange the following substances in a list in order of increasing boiling points. List beside each substance the type of bonding present in the solid state. For the molecular substances, also list the number of electrons per molecule, and note whether any of the substances are isoelectronic.

C8H18 C3H5(OH) C6H14 SiC C4H9Cl NaF Mg

41. In terms of electron mobility and electronegativity, explain why Na(s) is a very good conductor of electric current while NaCl(s) is a nonconductor.

For each bar on the graph, record and calculate the percentage contributions made by each type of force to the total intermolecular forces for CH3OH. (See Figure I15.)

.png”>.png”>.png”>.png”>.png”>.png”>.png”> 338

42. _____%

195

.png”>.png”>.png”>Boiling 43. _____%

Point (K) 186

.png”>

44. _____%

.png”> 0

C2H6(g) CH3F(g) CH3OH(l)

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