Introductory Chemistry, 5e (Tro)
Chapter 12 Liquids, Solids, and Intermolecular Forces
12.1 True/False Questions
1) Intermolecular forces are the attractive forces between atoms within a compound.
2) The shapes of protein molecules are determined by intermolecular forces.
3) Intermolecular forces determine if a substance is a solid, liquid or gas at room temperature.
4) Gases typically have high densities in comparison to solids.
5) Liquids can be easily compressed.
6) Atoms in a solid are always arranged in a well-ordered pattern.
7) Solids usually have much greater densities than gases because molecules of a solid are much
farther apart.
8) Without intermolecular forces, solids and liquids would not exist and all matter would be
gaseous.
9) The strength of the surface tension is inversely related to the strength of the intermolecular
forces.
10) Liquids that are viscous flow more slowly than liquids that are not viscous.
11) Viscosity increases with increased intermolecular force because the molecules attract each
other strongly which hinders the flow.
12) Evaporation is decreased by increasing the intermolecular forces.
13) Compounds with very high vapor pressures must have very minimal intermolecular forces.
14) The rate of evaporation will increase if you pour a liquid out onto a large surface.
15) Increasing the temperature increases the vaporization rate of a liquid because the excess
energy is used to break covalent bonds.
16) Oil would be considered a nonvolatile liquid while gasoline would be considered volatile.
17) The boiling point is the temperature at which the vapor pressure of a solution is equal to the
intermolecular forces.
18) Evaporation is an endothermic process.
19) Evaporation and condensation are opposite processes.
20) The process of heating a pot of water from room temperature to boiling temperature is an
exothermic process.
21) Water has a heat of vaporization of 44.0 kJ/mol while the chemical diethyl ether has a heat of
vaporization of 27.1 kJ/mol. This shows that one mole of water would vaporize more easily than
would one mole of diethyl ether.
22) When one mole of water vapor at 100°C condenses, it will release an amount of energy
equivalent to its heat of vaporization (40.7 kJ).
23) All intermolecular forces are broken when a liquid vaporizes into a gas.
24) Intermolecular forces hold atoms and molecules in place in a solid.
25) The melting point is reached when sufficient energy has been added to the molecules in a
substance to overcome the intermolecular forces holding them stationary.
26) Heat is released when a liquid freezes into a solid.
27) A glass of ice water containing nine ice cubes will be colder than a similar-size glass of ice
water containing only three ice cubes.
28) Sublimation is the process of a liquid being converted directly to a gas.
29) The heat of fusion for water is significantly more than the heat of vaporization for water
because fusion requires complete separation of one molecule from another.
30) Dispersion forces result from the temporary distortion of the electron cloud in an atom or
molecule which increases in magnitude with increasing size.
31) Dipole-dipole forces are weaker than dispersion forces.
32) Ion-dipole forces occur in mixtures of ionic compounds and polar compounds.
33) Hydrogen bonding occurs whenever hydrogen is present.
34) For hydrogen bonding to occur, a molecule must have a hydrogen atom bonded directly to a
fluorine, oxygen, or nitrogen atom.
35) Ion-dipole force is considered the weakest of the different types of intermolecular forces.
36) H2 boils at a higher temperature than He because H2 undergoes hydrogen bonding.
37) Ice is an example of a molecular solid.
38) Ionic solids tend to have higher melting points than molecular solids.
39) Atomic solids, such as graphite, have a weak dispersion force holding them together.
40) Attraction between the Na+ cation and Cl– anion holds the solid lattice of sodium chloride
together.
41) Water has unusual physical properties which enable life to exist on earth.
42) Ice can float in a glass of liquid water because the solid form of water is more dense than the
liquid form.
43) Compounds that are similar to water in molecular mass all exist as solids.
12.2 Multiple Choice Questions
1) Intermolecular forces are responsible for:
A) the taste sensations.
B) the shape of protein molecules.
C) the function of DNA.
D) the existence of liquids and solids.
E) all of the above
2) Which state of matter has a high density and an indefinite shape?
A) solids
B) liquids
C) gases
D) both solids and liquids
E) none of the above
3) Which state of matter has a high density and a definite volume?
A) solids
B) liquids
C) gases
D) both solids and liquids
E) none of the above
4) Which state of matter has a low density and an indefinite volume?
A) solids
B) liquids
C) gases
D) both solids and liquids
E) none of the above
5) Which state of matter has a low density and is easily compressed?
A) solids
B) liquids
C) gases
D) both solids and liquids
E) none of the above
6) Which statement about surface tension is FALSE?
A) Liquids tend to minimize their surface area.
B) Molecules on the surface of the liquid have fewer molecules to interact with.
C) Increased intermolecular forces increase surface tension.
D) Items with densities lower than water will sink due to surface tension.
E) All of the above statements are true.
7) The tendency of a liquid to minimize its surface area is called:
A) capillary action.
B) viscosity.
C) surface tension.
D) vaporization.
E) none of the above
8) The measure of the resistance to the flow of a liquid is called:
A) vapor pressure.
B) sublimation.
C) viscosity.
D) condensation.
E) none of the above
9) The change of a substance from a liquid to a gaseous form is called:
A) dynamic equilibrium.
B) heat of fusion.
C) condensation.
D) vaporization.
E) volatile.
10) A situation where two opposite processes are occurring at equal rates, and no net change is
taking place, is called:
A) vaporization.
B) condensation.
C) evaporation.
D) dynamic equilibrium.
E) none of the above
11) Increasing the intermolecular forces of a liquid will do which of the following?
A) increase the viscosity
B) decrease the evaporation rate
C) increase the surface tension
D) decrease the vapor pressure
E) all of the above
12) You can increase the vapor pressure of a liquid by:
A) increasing temperature.
B) increasing the viscosity.
C) establishing dynamic equilibrium.
D) using a nonvolatile compound.
E) all of the above
13) Which statement about boiling point is FALSE?
A) The boiling point is higher for compounds with strong intermolecular forces.
B) The boiling point is higher for compounds with a high viscosity.
C) The boiling point of a compound is an absolute constant.
D) The boiling point of a compound is higher for nonvolatile compounds.
E) All of the above statements are true.
14) Evaporation is:
A) increased by increasing temperature.
B) an endothermic process.
C) the opposite process to condensation.
D) a cooling process for humans when they sweat.
E) all of the above
15) Which of the following statements is FALSE?
A) Evaporation is an endothermic process.
B) A puddle of water cools down as it evaporates.
C) As a liquid is converted into a gas, the liquid absorbs heat.
D) All of the above are true.
E) None of the above are true.
16) The opposite process of freezing is:
A) evaporation.
B) sublimation.
C) boiling.
D) condensation.
E) none of the above
17) The rate of vaporization of a liquid can be increased by:
1. increasing the surface area
2. increasing the temperature
3. increasing the strength of the intermolecular forces
A) 1 only
B) 2 only
C) 3 only
D) 1 and 2 only
E) 2 and 3 only
18) Liquids that have high vapor pressure and low boiling points are called:
A) abnormal liquids.
B) volatile liquids.
C) non-volatile liquids.
D) viscous liquids.
E) none of the above
19) The amount of heat required to melt one mole of a solid is called the:
A) heat of vaporization.
B) heat of fusion.
C) heating curve.
D) cooling curve.
E) none of the above
20) Compare a small pot of water that is boiling vigorously to a large pot of water that is boiling
gently. Which statement is TRUE?
A) The small pot is boiling at higher temperature than the large pot.
B) The large pot is boiling at a higher temperature than the small pot.
C) Both pots are boiling at the same temperature.
D) The vapor pressure of the liquid is greater than the pressure above the pot in each case.
E) none of the above
21) When sufficient quantity of heat has been added to reach the boiling point of a solution, what
happens to any additional heat added?
A) Additional heat is used to evaporate the liquid as the process is endothermic and requires
continued input of energy.
B) Additional heat raises the temperature of the liquid which in turn increases the rate at which
boiling occurs.
C) Additional heat lowers the intermolecular forces of the liquid which in turn increases the
volatility of the liquid.
D) Additional heat alters the viscosity and the surface tension of the liquid which raises the vapor
pressure and increases the boiling point which is why you must continually heat the solution.
E) None of the above are correct statements.
22) What is the heat of vaporization(kJ/mol) if it takes of heat to completely vaporize
of the liquid at its boiling point?
A) 1288
B) 1.29
C) 0.776
D) 12.2
E) none of the above
23) How many joules of heat are needed to completely vaporize of water at its boiling
point?
Given = 40.6 kJ/mol
A) 54.97
B)
C) 29.98
D)
E) none of the above
24) How many kilojoules of heat are needed to completely vaporize of at its
boiling point?
Given = 26.5kJ/mol
A) 74.12
B) 9.49
C) 15.3
D) 16.3
E) none of the above
25) What happens as you start to add heat to a solid substance?
A) Thermal energy causes the components of the solid to vibrate faster.
B) When the melting point is reached, the thermal energy is sufficient to overcome
intermolecular forces holding the components at their stationary points.
C) Increasing the rate of heating of a substance at its melting point only causes more rapid
melting.
D) If a liquid forms, continued heating results in increasing the liquid temperature.
E) all of the above