Cliffs AP Chemistry, 3rd Edition

9. The molecules butane and 2-methylpropane are structural isomers. Which of the
   following characteristics would be the same for both isomers, assuming constant
   temperature where necessary?

A. Boiling point

B. Vapor pressure

C. Melting point

D. Solubility

E. Gas density

Answer: E

Choices A, B, C, and D involve the strength of intermolecular forces. Because the two com-
pounds differ in structure, there would be intermolecular differences between the two com-
pounds. However, because both isomers have the same molecular mass, they would have the
same gas density.

10. Which of the following choices represents intermolecular forces listed in order from

strongest to weakest?

A. dipole attractions, dispersion forces, hydrogen bonds

B. hydrogen bonds, dispersion forces, dipole attractions

C. dipole attractions, hydrogen bonds, dispersion forces

D. hydrogen bonds, dipole attractions, dispersion forces

E. dispersion forces, hydrogen bonds, dipole attractions

Answer: D

Hydrogen bonds are the strongest of the intermolecular forces listed; dispersion forces are the
weakest.

11. Arrange the following in order of increasing boiling point: NaCl, CO 2 , CH 3 OH, CH 3 Cl.

A. CH 3 Cl, CO 2 , CH 3 OH, NaCl

B. CO 2 , CH 3 Cl, CH 3 OH, NaCl

C. CO 2 , CH 3 OH, CH 3 Cl, NaCl

D. NaCl, CH 3 OH, CH 3 Cl, CO 2

E. CH 3 OH, CO 2 , CH 3 Cl, NaCl

Answer: B

Part II: Specific Topics