Chapter 11 – Intermolecular Forces and Liquids and Solids
123. Osmium tetroxide, OsO4, is a soft crystal that melts at 40C. The liquid does not conduct
electricity. What kind of crystal is this?
124. Boron nitride, BN3, melts at approximately at 3,000C under high pressure. This material
is almost as hard as diamond. What kind of crystal is this?
Chapter 11 – Intermolecular Forces and Liquids and Solids
125. Crystals of elemental sulfur are easily crushed, and melt at 113C. Liquid sulfur does not
conduct electricity. What kind of crystal is this?
126. Magnesium oxide, MgO, melts at 2,800C and is very hard. The liquid conducts
electricity very well. What kind of crystal is this?
127. Sodium iodide, NaI, melts at 651C. In its liquid state NaI conducts electricity. What
kind of crystal is this?
130. Methane has a heat of fusion of 0.84 kJ/mol and a heat of vaporization of 9.2 kJ/mol.
Estimate the value for the heat of sublimation.
131. Select True or False: Ethanol has a higher boiling point than dimethyl ether. (Ethanol and
dimethyl ether have the same molecular formula, C2H6O. Their structural formulas are,
respectively, CH3CH2OH and CH3OCH3.)
Chapter 11 – Intermolecular Forces and Liquids and Solids
132.
Polyethylene plastic consists of long chains of carbon atoms, each of which is also bonded to hydrogens as shown below:
Water forms beads when placed on a polyethylene surface. Why?
Chapter 11 – Intermolecular Forces and Liquids and Solids
133. Select True or False: At a given temperature CCl4 has a weaker surface tension than
H2O.
Chapter 11 – Intermolecular Forces and Liquids and Solids
134.
Select True or False: Based on the phase diagram shown below, the solid phase is more dense than the liquid phase.
Chapter 11 – Intermolecular Forces and Liquids and Solids
135.
Select True or False: The gas phase exists at the point labeled a.
Chapter 11 – Intermolecular Forces and Liquids and Solids
136.
Select True or False: The liquid phase exists at the point labeled b.
Chapter 11 – Intermolecular Forces and Liquids and Solids
137.
Select True or False: The gas phase exists at the point labeled c.
Chapter 11 – Intermolecular Forces and Liquids and Solids
138.
Select True or False: Suppose the atoms in a two-dimensional crystal have the following arrangement:
On the drawing below the lines connect four spheres which represents the unit cell of this crystal.
Chapter 11 – Intermolecular Forces and Liquids and Solids
139.
Suppose the atoms in a two-dimensional crystal have the following arrangement:
How many atoms are in one unit cell?
A) One
B) Two
C) Three
D) Four
E) None of the above
Chapter 11 – Intermolecular Forces and Liquids and Solids
140.
Suppose the atoms in a two-dimensional crystal have the following arrangement:
What is the coordination number of each atom in this crystal?
Chapter 11 – Intermolecular Forces and Liquids and Solids
141.
Calculate the amount of enthalpy required to heat 25.0 g of solid benzene (C6H6) at –10C to liquid benzene at 20.0C.
Thermodynamic data for benzene: specific heat of solid benzene = 1.52 J/g·C; specific heat of liquid benzene = 1.73 J/g·C;
melting point = 5.5C; Hfus = 9.9 kJ/mol.
Chapter 11 – Intermolecular Forces and Liquids and Solids
142.
How much enthalpy is necessary to heat 10.0 g of solid benzene (C6H6) at 0.0C to benzene vapor at 100C?
Chapter 11 – Intermolecular Forces and Liquids and Solids
143.
Given that the heat of vaporization of diethyl ether is 26.0 kJ/mol and the vapor pressure of diethyl ether is 440 torr at 20.C,
calculate the normal boiling point of diethyl ether.
144. Given that the heat of vaporization of mercury is 59.0 kJ/mol and the vapor pressure of
mercury is 0.0017 torr at 25C, calculate the normal boiling point of mercury.
Chapter 11 – Intermolecular Forces and Liquids and Solids
145. Select True or False: Octane, C8H18, boils at 125C as compared to water, which boils at
100C. This information suggests that the dispersion forces in nonpolar octane molecules are
stronger than dispersion forces and hydrogen bonding in water.
146. Select True or False: Ethanol (C2H5 – OH) will have a greater viscosity than ethylene
147. Select True or False: The shape of the water-to-glass meniscus results from the strong
adhesive forces between glass and water.
Chapter 11 – Intermolecular Forces and Liquids and Solids
148. Select True or False: The density of ice is less than the density of liquid water due to the
formation of hydrogen bonds.
149. Select True or False: The freezing point of a liquid does not change as the atmospheric
150. Select True or False: All intermolecular forces must be overcome in order for a
substance to undergo a phase change from a solid to a liquid.
Chapter 11 – Intermolecular Forces and Liquids and Solids
151. Select True or False: All intermolecular forces must be overcome in order for a
substance to undergo a phase change from a liquid to a gas