GENERAL CHEMISTRY II
CHEM 1312
EXAM 1
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1. What state of matter is characterized by molecules that are close together, and almost locked in fixed positions, with motion being limited to vibration around those fixed positions? a) solid b) liquid c) gas
2. Gases are a) readily compressible b) virtually incompressible
3. The graph below shows a heating curve for converting ice at -10 o C to steam at 110 o C. In what region of the graph is liquid water being heated? a) region 1 b) region 2 c) region 3 d) region 4 e) region 5
4. Referring to the above heating curve, in which regions are two states of matter simultaneously stable? a) regions 1, 3, and 5 b) regions 2 and 4
5. The rate of evaporation of a liquid from an open container depends on a) the temperature of the liquid b) the surface area of the liquid c) the strength of the intermolecular attractive forces in the liquid d) both a and c e) all of the above (a, b and c)

6. The equilibrium vapor pressure of a liquid in a closed container depends on a) the temperature of the liquid b) the surface area of the liquid c) the strength of the intermolecular attractive forces in the liquid d) both a and c e) all of the above (a, b and c)
7. The graph below shows the equilibrium vapor pressure of selected liquids as a function of temperature.
Which of these liquids has the strongest intermolecular attractive forces? a) diethyl ether b) ethyl alcohol c) ethylene glycol d) water
8. According to the graph in Question 7, ethyl alcohol will boil at _____ when the external pressure is 600 torr. a) 25 o
C b) 42 o
C c) 60 o
C d) 74 o
C e) 85 o
C
9. According to the graph in Question 7, the equilibrium vapor pressure of water at 80 o
C is approximately a) 150 torr b) 200 torr c) 360 torr d) 610 torr e) 720 torr

10. The heat of vaporization of water at its normal boiling point is 40.7 kJ/mol. How much heat is required to boil 75.00 g of water into steam at 100 o
C? Atomic weights: H 1.008 O 16.00 a) 85.7 kJ b) 169 kJ c) 283 kJ d) 407 kJ e) 562 kJ
11. After the 75.00 g of water in Question 10 has been converted into steam (by absorbing the correct amount of heat, as calculated in that problem – no more, no less) how does the temperature of the steam compare to the starting temperature of the water (100 o C)? And what is the reason for this?
a) The steam will be at 100 o
C, because phase changes take place at constant temperature.
b) The steam will be hotter than 100 o
C, because heat was added during the boiling process.
c) The steam will be hotter than 100 o
C, because boiling is an exothermic process.
d) The steam will be cooler than 100 o
C, because boiling is an endothermic process.
12. How can you boil water at room temperature?
a) You can’t. Water always boils at 100 o
C, which is well above room temperature.
b) By putting the water under sufficiently high pressure, it can be made to boil at room temperature.
c) By putting the water under sufficiently low pressure, it can be made to boil at room temperature.
13. On the phase diagram below, region 1 corresponds to those combinations of temperature and pressure where only the __________ state is stable.
a) solid b) liquid c) supercritical fluid d) gas

14. On the phase diagram in Question 13, curve 3 is the a) fusion curve b) sublimation curve c) vaporization curve
15. According to the phase diagram in Question 13, compressing water vapor at very low temperatures converts the gas to a a) liquid b) solid c) supercritical fluid
16. On the phase diagram in Question 13, point A is known as the __________ point. a) critical b) fiduciary c) intersection d) low e) triple
17. A supercritical fluid exists when the temperature is __________ the critical temperature and the pressure is __________ the critical pressure. a) above, above b) below, below c) above, below d) below, above
18. In class, we discussed the compression of a gas in a cylinder, under conditions where condensation to the liquid state was possible. We considered how the pressure and volume were related for such a system.
An illustration was presented, in which 3 molecular-level drawings were placed over the appropriate region of the pressure-volume graph, to help relate the pressure changes to what was happening at the atomic level. That illustration is shown below, but has been ALTERED, to make it WRONG! Chose the answer below that indicates the correct order of the numbered cylinders, reading from left to right. a) 2, 1, 3 b) 1, 3, 2 c) 3, 2, 1 d) 3, 1, 2 e) 2, 3, 1

19. The illustration below shows what happens to a liquid-vapor equilibrium system as the temperature is raised. The temperature increases as you proceed from left to right in the drawing. At sufficiently low temperatures, there is a clear distinction between the liquid state and the gaseous state, due to their dramatically different densities. With heating, however, the distinction begins to blur, and eventually, the two states merge into one. This single state, seen on the right hand side of the illustration, is best referred to as a a) liquid b) supercritical fluid c) solid d) gas
20. If a liquid has a heat of vaporization of 38.50 kJ/mol and exerts a vapor pressure of 421 torr at 65 o C, what is its normal boiling point? The gas constant R has the value 8.314 J / mol K. a) 80 o
C b) 98 o
C c) 125 o
C d) 187 o
C e) 250 o
C
21. If a liquid has a heat of vaporization of 32.65 kJ/mol and a normal boiling point of 68 o C, what is its equilibrium vapor pressure at 25 o
C? The gas constant R has the value 8.314 J / mol K. a) 45.7 torr b) 86.3 torr c) 144 torr d) 192 torr e) 281 torr
22. If a liquid has an equilibrium vapor pressure of 134 torr at 0 o
C and a normal boiling point of 40 o
C, what is its heat of vaporization (ΔH vap
)? The gas constant R has the value 8.314 J / mol K. a) 15.2 kJ/mol b) 30.9 kJ/mol c) 42.8 kJ/mol d) 61.7 kJ/mol e) 77.1 kJ/mol
23. While the strength of intermolecular forces can depend on a number of factors, if we are careful to
“compare apples with apples” (similar molecules), we generally rank the three intermolecular forces in this order of strength: a) (weakest) hydrogen bonding < London forces < dipole-dipole forces (strongest) b) (weakest dipole-dipole forces < London forces < hydrogen bonding (strongest) c) (weakest) London forces < hydrogen bonding < dipole-dipole forces (strongest) d) (weakest) dipole-dipole forces < hydrogen bonding < London forces (strongest) e) (weakest) London forces < dipole-dipole forces < hydrogen bonding (strongest)

24. Methane (CH
4
) and pentane (C
5
H
12
) are both non-polar molecules. Their Lewis structures are shown below. Would the intermolecular attractive forces be expected to be stronger in liquid methane or in liquid pentane? Atomic weights: H 1.008 C 12.01 a) Intermolecular attractive forces should be stronger in liquid methane. b) Intermolecular attractive forces should be stronger in liquid pentane. c) Intermolecular attractive forces should be the same in liquid methane and liquid pentane, since both molecules are non-polar. d) There is not enough information to make a prediction.
25. Which of the two substances in question 24 would have the lower normal boiling point? a) Methane b) Pentane c) There is not enough information to make a prediction
26. A molecule of H
2
O can form hydrogen bonds with a molecule of a) CH
4 b) NH
3 c) PH
3 d) All of these e) None of these
27. Can two H
2
O molecules form a hydrogen bond to each other? a) Yes b) No
28. Can two CH
4
molecules form a hydrogen bond to each other? a) Yes b) No
29. Consider an element that crystallizes in a face-centered cubic unit cell. How many atoms are present in this unit cell? a) 1 b) 2 c) 4 d) 6 e) 8
30. An atom that is located on the corner of a unit cell is shared among a total of _____ unit cells. a) 2 b) 4 c) 6 d) 8 e) 12
31. Elemental chromium crystallizes in a body-centered cubic lattice with a unit cell edge length of 2.91 Ǻ.
The atomic weight of chromium is 52.00 g/mol, and Avogadro’s number is 6.022 x 10 23
atoms/mol.
What is the density of chromium? Note: 1 Ǻ = 1 x 10
-8
cm a) 4.23 g/cm
3 b) 7.01 g/cm
3 c) 11.5 g/cm
3 d) 19.8 g/cm
3 e) 28.4 g/cm
3
32. Silver (Ag) crystallizes in one of the cubic lattice structures – that is, it is either simple cubic, bodycentered cubic, or face-centered cubic. Using the atomic weight of silver (107.87 g/mol), Avogadro’s number (6.022 x 10
23
atoms/mol), the edge length of the silver unit cell (4.085 Ǻ), and the density of silver (10.49 g/cm
3
), decide which type of cubic lattice silver has. Hint: calculate the number of atoms per unit cell. Because of round-off error, you might not get a perfect integer. But you should get very close to an integer – off by no more than 1 or 2 in the 3 rd
significant figure. a) body-centered cubic b) face-centered cubic c) simple cubic
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