CHM 2046C Module 7II:
Chapter 13 Sample Multiple Choice Test #2 AnswersTop of Form

 

1. The correct answer is:
40.

Explanation:
The vapor pressure of a substance is independent of the size of container. Why?

Solution Reference:
Page 602, Vapor Pressure

1. One mole of propan-2-ol, C3H7OH, is placed in a 250 cm3 flask. Another mole of propan-2-ol is placed in a 1000 cm3 flask. Both flasks are sealed and maintained at the same temperature. The vapor pressure of propan-2-ol in the 250 cm3 flask at 24°C is 40 mm Hg. In the 1000 cm3 flask the vapor pressure in mm Hg is

a.

10.

b.

20.

c.

40.

d.

80.

e.

160.

 

 

2. The correct answer is:
The average kinetic energy of molecules is greater, thus more molecules can enter the gaseous state.

Explanation:
More molecules have sufficient energy to escape from the liquid. The intermolecular forces between the molecules are just as strong at a higher temperature, but they become less important as the kinetic energy increases.

Solution Reference:
Page 599, Enthalpy of Vaporization and Page 602, Vapor Pressure

2. The vapor pressure of a liquid increases with an increase of temperature. Which of the following statements best explains this increase?

a.

The average kinetic energy of molecules is greater, thus more molecules can enter the gaseous state.

b.

The number of gaseous molecules above the liquid remains constant, but these molecules have greater average kinetic energy.

c.

The faster moving molecules in the liquid exert a greater pressure.

d.

All the molecules have greater kinetic energies.

e.

The intermolecular forces between the molecules becomes less at higher temperature.

 

3. The correct answer is:
is the temperature at which the vapor pressure is 1 atm.

Explanation:
Response (a) is only correct for water but all liquids have their own characteristic boiling points. Responses (d) and (e) define boiling but not the normal boiling point.

Solution Reference:
Page 605, Boiling Point

3. The normal boiling point of a liquid

a.

is 100°C at 1 atm pressure.

b.

is the temperature at which the vapor pressure is 1 atm.

c.

is the temperature at which liquid and vapor are in equilibrium.

d.

is the temperature at which the vapor pressure equals the external pressure.

e.

is the temperature at which there is a continuous formation of gaseous bubbles in the liquid.



 

4. The correct answer is:
ln P versus 1/T.

Explanation:

The equation above which illustrates vapor pressure dependence as a function of temperature is known as the Clausius-Clapeyron equation. From such a relationship (from the slope of a straight line) it is possible to obtain DHvap, the heat of vaporization.

4. The data for the equilibrium pressure of any liquid as a linear function of temperature can best be represented by plotting

a.

ln P versus t.

b.

ln P versus T.

c.

ln P versus 1/T.

d.

P versus t.

e.

P versus T.



 

 

 

 

5. The correct answer is:
a very high vapor pressure.

Explanation:
A low vapor pressure is an indication of strong intermolecular forces of attraction between molecules.

Solution Reference:
Page 602, Vapor Pressure

5. All of the following indicate very strong intermolecular forces of attraction in a liquid EXCEPT

a.

a very high boiling point.

b.

a very high vapor pressure.

c.

a very high critical temperature.

d.

a very high viscosity.

e.

a very high heat of vaporization.

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6. The correct answer is:
C4H10

Explanation:
Another question to ask is which compound has the lowest boiling point. The smallest molecule will have the lowest boiling point, the weakest intermolecular forces.

Solution Reference:
Page 595, Dispersion Forces

6. Which compound should have the highest vapor pressure at room temperature?

a.

C4H10

b.

C5H12

c.

C6H14

d.

C7H16

e.

C8H18



 

7. The correct answer is:
CH3NH2

Explanation:
In methylamine, CH3NH2, there is a hydrogen atom bonded to the nitrogen. In dimethylether, CH3OCH3, there is no hydrogen bonding because no hydrogen atoms are bonded to oxygen.
Solution Reference:
Page 590, Hydrogen Bonding

7. Which of the following compounds shows an abnormal boiling point due to hydrogen bonding?

a.

CH3NH2

b.

CH3OCH3

c.

CH3SH

d.

CH3Cl

e.

HCl



 

8. The correct answer is:
CH3OH.

Explanation:
Which compound has the highest boiling point? In which compound is there hydrogen bonding between the molecules?

Solution Reference:
Page 590, Hydrogen Bonding and Page 605, Critical Temperature

8. Of the following substances, the one expected to have the highest critical temperature is

a.

CH3OH.

b.

CH3Cl.

c.

CH4.

d.

C2H6.

e.

C3H8.



 

9. The correct answer is:
Si2Cl6

Explanation:
Which molecule is the largest? Which compound should have the highest boiling point?

Solution Reference:
Page 595, Dispersion Forces

 

 

 

9. What compound should have the lowest vapor pressure at room temperature?

a.

SiH4

b.

Si2H6

c.

Si2Cl6

d.

Si3H8

e.

Si4H10



 

10. The correct answer is:
CH3CH2NH2

Explanation:
Which compound has hydrogen bonding? Why isn't there hydrogen bonding in CH3CH2F?

Solution Reference:
Page 599, Enthalpy of Vaporization and Page 590, Hydrogen Bonding

10. Which of the following would be expected to have the highest heat of vaporization?

a.

CH3CH2CH3

b.

CH3OCH3

c.

CH3CHO

d.

CH3CH2NH2

e.

CH3CH2F

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 11. The correct answer is:
SX = solid-gas, RX = solid-liquid, XZ = gas-liquid

Explanation:
N represents the solid area, O represents the liquid area, and M the gaseous area.

Solution Reference:
Page 629, Phase Diagrams

11. The lines in the diagram represent values of pressure and temperature at which two phases may be present in equilibrium. Which one of the following descriptions of the lines SX, RX, and XZ is the correct one?

 

a.

SX = solid-liquid, RX = solid-gas, XZ = gas-liquid

b.

SX = solid-gas, RX = solid-liquid, XZ = gas-liquid

c.

SX = solid-liquid, RX = gas-liquid, XZ = solid-gas

d.

SX = gas-liquid, RX = solid-gas, XZ = solid-liquid

e.

SX = gas-liquid, RX = solid-liquid, XZ = solid-gas



 

12. The correct answer is:
sublimation.

Explanation:
Point N is in the solid state and Point M is in the gaseous state.

Solution Reference:
Page 629, Phase Diagrams

12. From a consideration of the phase diagram below, a change from point N to point M corresponds to

a.

sublimation.

b.

vaporization.

c.

condensation.

d.

liquefaction.

e.

freezing.



 

13. The correct answer is:
sublimation.

Explanation:
A substance going directly from solid state to the gaseous undergoes sublimation.

Solution Reference:
Page 625, The Physical Properties of Solids

 

 

 

13. The process which is represented by the equation, K(s) --> K(g), is

a.

fusion.

b.

melting.

c.

sublimation.

d.

vaporization.

e.

condensation.



 

14. The correct answer is:
heat of sublimation minus heat of vaporization.

Explanation:


Solution Reference:
Page 625, The Physical Properties of Solids

14. The heat of fusion of a compound equals

a.

heat of vaporization plus heat of crystallization.

b.

heat of fusion plus heat of vaporization.

c.

heat of sublimation minus heat of vaporization.

d.

heat of vaporization minus heat of fusion.

e.

heat of ionization plus heat of crystallization.



 

15. The correct answer is:
hydrogen

Explanation:
Potassium has a metallic bonding (no discrete metal atoms). Glass and quartz both consist of giant SiO2 molecules. Silicon carbide has a 3-dimensional diamond like structure and it is a giant molecule. The intermolecular forces between the hydrogen molecules are van der Waal type interactions.

Solution Reference:
Page 609, Metallic and Ionic Solids

15. Which of the following as solids has a crystal structure containing discrete (or separate) molecules?

a.

potassium

b.

glass

c.

quartz

d.

carborundum, SiC

e.

hydrogen

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16. The correct answer is:
a covalent solid.

Explanation:
The solid is probably a large macromolecule such as silicon carbide, diamond or silicon dioxide.

Solution Reference:
Page 621, Other Kinds of Solid Materials

16. A solid has a very high melting point, it is very hard, and its liquid is nonconducting. The solid is

a.

an ionic solid.

b.

a covalent solid.

c.

a metallic solid.

d.

an atomic solid.

e.

a molecular solid.

 

 

17. The correct answer is:
MgCl2

Explanation:
We should only consider the ionic compounds LiCl, NaCl, and MgCl2. MgCl2 should have the highest crystal lattice energy because of the charge on the Mg2+ ion.

Solution Reference:
Page 609, Metallic and Ionic Solids

17. Which of the following compounds would be expected to have the highest melting point?

a.

LiCl

b.

NaCl

c.

MgCl2

d.

BaCl2

e.

BCl3



 

18. The correct answer is:
ABC3

Explanation:
# A = 8 x 1/8 = 1 # B = 1 x 1 = 1 # C = 6 x 1/2 = 3

Solution Reference:
Page 610, Crystal Lattices

18. What is the simplest formula of a solid containing A, B, and C atoms in a cubic lattice in which the A atoms occupy the corners, the B atoms, the body-centered position and the C atoms, the faces of the unit cell?

a.

ABC

b.

ABC3

c.

ABC6

d.

A8BC6

e.

A4BC3



 

19. The correct answer is:
XY.

Explanation:
# X atoms = 1 x 1 = 1 # Y atoms = 1 x 1/8 = 1

Solution Reference:
Page 610, Crystal Lattices

19. A crystalline compound consists of two types of atoms, X and Y. It crystallizes in a cubic lattice with one X atom at the body center Y atoms at the corners of the unit cell. The simplest formula of this compound is

a.

XY8.

b.

X2Y.

c.

XY.

d.

XY2.

e.

X8Y.



20. The correct answer is:
a body-centered cubic structure.

Explanation:
8 x 1/8 + 1 x 1 = 2

Solution Reference:
Page 610, Crystal Lattices

20. Tungsten crystallizes in a cubic lattice with two atoms of W per unit cell. It could be classified as

a.

a body-centered cubic structure.

b.

a face-centered cubic structure.

c.

a simple cubic structure.

d.

a cubic closest packing structure.

e.

a hexagonal closest packing structure.

 

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21. The correct answer is:
8

Explanation:
There are 2 Na+/1 O2- #O2- = 8 x 1/8 + 6 x 1/2 = 4

Solution Reference:
Page 610, Crystal Lattices

21. The oxide ions in Na2O form a face-centered cubic lattice and the sodium ions occupy all the tetrahedral holes. The oxide ions occupy the faces and the corners of the unit cell. How many sodium ions are in one unit cell?

a.

2

b.

4

c.

6

d.

8

e.

12



 

22. The correct answer is:
4

Explanation:


Solution Reference:
Page 610, Crystal Lattices

22. Titanium dioxide crystallizes in a noncubic crystal system (a tetragonal system). In this structure, two of the O2- ions are within the interior of the cell, two are in the top face, and two in the bottom face of the cell. Ti4+ ions are at the corners and the center of the cell. How many oxide ions are there per unit cell?

a.

1

b.

2

c.

3

d.

4

e.

6



 

23. The correct answer is:
0.144

Explanation:


Solution Reference:
Page 610, Crystal Lattices

23. Silver crystallizes in the face-centered cubic system. If the edge of the unit cell is 0.407 nm, what is the radius of a silver atom in nm?

a.

0.144

b.

0.176

c.

0.206

d.

0.288

e.

0.352



 

24. The correct answer is:
A face-centered cubic cell.

Explanation:
A face-centered cubic has more atoms per unit cell. A simple cubic structure has one atom per unit cell. A body-centered cubic structure has two atoms per unit cell. A face-centered cubic structure has four atoms per unit cell.

Solution Reference:
Page 610, Crystal Lattices

24. Solid nickel has a cubic unit cell. The edge of the cubic cell is 3.0 x 10-8 cm. Which of the cubic unit cells described below would give nickel its highest density?

a.

A simple cubic cell.

b.

A body-centered cubic cell.

c.

A face-centered cubic cell.

d.

The density would be identical for all of the cells above if the edge of each cell was 3.0 x 10-8 cm.

e.

Cannot determine since the size of the nickel atom is not given.



 

25. The correct answer is:
BaF2

Explanation:
Which compound is an ionic compound?

Solution Reference:
Page 609, Ionic Solids

25. Which of the following substances is most likely to exist as a solid at room temperature?

a.

NF3

b.

PF5

c.

SF6

d.

BF3

e.

BaF2

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