11: Intermolecular Forces and Liquids
- Page ID
- 204590
Downloadable files
- Please print and work out the question before looking at the answers
- Chapter 11: Intermolecular Forces and Liquids pdf
General Questions
Exercise \(\PageIndex{1}\)
What is the dominant intermolecular force in H2?
- London Dispersion (instantaneous dipole-induced dipole)
- dipole-dipole
- ion-dipole
- hydrogen bonding
- Answer
-
a. London Dispersion (instantaneous dipole-induced dipole)
Exercise \(\PageIndex{2}\)
What is the major intermolecular force in H2O?
- London Dispersion (induced dipole-induced dipole)
- dipole-dipole
- ion-dipole
- hydrogen bonding
- Answer
-
d. hydrogen bonding
Exercise \(\PageIndex{3}\)
What is the major intermolecular force responsible for the dissolution of NaCl in H2O?
- London Dispersion (induced dipole-induced dipole)
- dipole-dipole
- ion-dipole
- hydrogen bonding
- Answer
-
c. ion-dipole
Exercise \(\PageIndex{4}\)
Which force is strongest?
- dipole/dipole
- ion/dipole
- London Dispersion
- covalent
- Answer
-
d. covalent
Exercise \(\PageIndex{5}\)
Hydrogen bonding is a special case of:
- dipole-dipole forces
- ion-dipole forces
- covalent bonding
- London Dispersion Forces
- Answer
-
a. dipole-dipole force
Exercise \(\PageIndex{6}\)
Which has the highest boiling point? (F2, Cl2, Br2, I2)
- Answer
-
d. I2, these are all homonuclear diatomics, and Iodine is both the heaviest (largest mass) and most polarizable (largest volume).
Exercise \(\PageIndex{7}\)
Which has the highest boiling point? (HF, HCl, HI, HBr)
- Answer
-
a. HF, although it is the lightest (which would have you think it would have a low boiling point), it has strong hydrogen bonds, which take a lot of energy to overcome, and so has a high boiling point.
Exercise \(\PageIndex{8}\)
Which of the following molecules are not involved with hydrogen bonding?
- H2,NH3
- HI,HBr
- HF,NH3
- HCOOH,H2O
- Answer
-
b. HI, HBr
Exercise \(\PageIndex{9}\)
Which has the lowest boiling point? (He, Ne, Kr, Ar)
- Answer
-
a. He
Exercise \(\PageIndex{10}\)
Which is more polarizable? (O, S, Se, Te)
- Answer
-
d. Te
Exercise \(\PageIndex{11}\)
Placed the following compounds in the order of instantaneous dipole, dipole/dipole and hydrogen bonding as the primary intermolecular forces. (H2O, H2Se, CH4)
- Answer
-
CH4, H2Se, H2O
Exercise \(\PageIndex{12}\)
Arrange the following compounds in order of increasing boiling points. (H2O, H2S, H2Se, H2Te)
- Answer
-
H2S < H2Se < H2Te < H2O
Exercise \(\PageIndex{13}\)
Arrange the following compounds in order of increasing boiling point. (H2O, HF, NH3, CH4)
- Answer
-
CH4 < NH3 < HF < H2O
Exercise \(\PageIndex{14}\)
Which compound is the most polarizable? (I2, H2, F2, Br2)
- Answer
-
I2
Exercise \(\PageIndex{15}\)
Which species cannot be involved with hydrogen bonding? (HF, H2O, NH3, NH4+)
- Answer
-
NH4+
Exercise \(\PageIndex{16}\)
What intermolecular force is responsible for the dissolution of oxygen into water?
- hydrogen bonding
- instantaneous-induced dipole
- dipole-induced dipole
- dipole-dipole
- Answer
-
C. dipole-induced dipole
Exercise \(\PageIndex{17}\)
Which has the highest boiling point? (CH4, SiH4, GeH4, SnH4)
- Answer
-
SnH4
Exercise \(\PageIndex{18}\)
Which has the lowest boiling point? (CH4, SiH4, GeH4, SnH4)
- Answer
-
CH4
Exercise \(\PageIndex{19}\)
Which has the highest boiling point? (NH3, PH3, CH4, SiH4)
- Answer
-
NH3
Exercise \(\PageIndex{20}\)
What angle best approximates the geometric structure of ice? (90°, 109°, 120°, 180°)
- Answer
-
109°

Exercise \(\PageIndex{21}\)
Which set of curves would represent the effect of increasing temperature on the vapor pressure of a liquid?
- A & B
- C & D
- All of them
- None of them
- Answer
-
a. A & B
Exercise \(\PageIndex{22}\)
The normal boiling point is defined as:
-
100°C
-
The boiling pt. at 1 atm
-
The boiling pt. on planet earth
-
None of the above
- Answer
-
b. The boiling pt. at 1 atm
Exercise \(\PageIndex{23}\)
The normal boiling point of diethyl ether is 34.6°C and of water is 100°C. Which has the higher vapor pressure at 20°C?
- water
- diethyl ether
- they are the same
- it depends on your elevation
- Answer
-
b. diethyl ether
Exercise \(\PageIndex{24}\)
If one of the compounds in question 1 is diethyl ether and the other is water, curve___is diethyl ether and curve___is water.
- A,B
- B,A
- C,D
- D,C
- Answer
-
a. A,B
Exercise \(\PageIndex{25}\)
A liquid is _____ and assumes _____ of its container whereas a gas is _____ and assumes _____ of its container.
- Compressible, the volume and shape, condensed, the shape
- Compressible, the volume, compressible, the volume and shape
- Condensed, the volume and shape, condensed, the volume and shape
- Not compressible, the shape of a portion, compressible, the volume and shape
- Not compressible, the volume and shape, compressible, the shape
- Answer
-
d. Not compressible, the shape of a portion, compressible, the volume and shape
Exercise \(\PageIndex{26}\)
Choose the following molecule that exhibits dipole-dipole attractions? (AsH3, BCl3, Cl2, CO2, XeF4)
- Answer
-
AsH3
Exercise \(\PageIndex{27}\)
What is the predominant intermolecular force in KBr?
- Dipole-dipole attraction
- Hydrogen-bonding
- Ion-dipole attraction
- Ionic bonding
- London-dispersion forces
- Answer
-
d. Ionic bonding
Exercise \(\PageIndex{28}\)
What are the principal difference in the normal boiling points of ICl (97°C; molecular mass 162 amu) and Br2 (59°C; molecular mass 160 amu)?
- Both dipole-dipole interactions and London-dispersion forces
- Both hydrogen-bonding and dipole-dipole interactions
- Dipole-dipole interactions
- Hydrogen bonding
- London-dispersion forces
- Answer
-
c. Dipole-dipole interactions
Exercise \(\PageIndex{29}\)
Explain the reason why iodine is a solid, bromine is a liquid, and chlorine is a gas at room temperature.
- Answer
-
Van der Waals forces increase going down the periodic table. Thus Chlorine has the weakest van der Waals forces and Iodine has the strongest with bromine being in the middle.
Exercise \(\PageIndex{30}\)
The _____ is the attractive force between an instantaneous dipole and an induced dipole.
- Dipole-dipole attraction
- Hydrogen-bonding
- Ion-dipole attraction
- Ionic bonding
- London dispersion forces
- Answer
-
e. London dispersion forces
Exercise \(\PageIndex{31}\)
Choose the ethane molecule that has the highest boiling point.
- C2Br6
- C2Cl6
- C2F6
- C2H6
- C2I6
- Answer
-
e. C2I6
Exercise \(\PageIndex{1=32}\)
What is the major attractive force that exists among different I2 (elemental iodine, I2, is a solid at room temperature) molecules in the solid?
- Covalent-ionic interactions
- Dipole-dipole attractions
- Dipole-dipole rejections
- Ionic-dipole interactions
- London dispersion forces
- Answer
-
e. London dispersion forces
Exercise \(\PageIndex{33}\)
Hydrogen bonding is a special case of what other intermolecular forces?
- Dipole-dipole attractions
- Ion-dipole attraction
- Ion-ion interactions
- London-dispersion forces
- None of these
- Answer
-
a. Dipole-dipole attractions
Exercise \(\PageIndex{34}\)
Which of the following has the highest boiling point? (N2, Br2, H2, Cl2, O2)
- Answer
-
Br2
Exercise \(\PageIndex{35}\)
The molecules in C12H26 are held together by _____.
- Dipole-dipole interactions
- Dispersion forces
- Hydrogen bonding
- Ion-dipole interactions
- Ion-ion interactions
- Answer
-
b. Dispersion forces
Exercise \(\PageIndex{36}\)
The shape of a liquid’s meniscus is determined by _____.
- the relative magnitudes of cohesive forces in the liquid and adhesive forces between the liquid and its container
- the type of material the container is made of
- the viscosity of the liquid
- the volume of the liquid
- Answer
-
a. the relative magnitudes of cohesive forces in the liquid and adhesive forces between the liquid and its container
Exercise \(\PageIndex{37}\)
Viscosity is _____.
- Inversely proportional to molar mass
- The “skin” on a liquid surface caused by intermolecular attraction
- The resistance to flow
- The same as density
- Unaffected by temperature
- Answer
-
c. The resistance to flow
Exercise \(\PageIndex{38}\)
What property is responsible for the “beading up” of water?
- density
- hydrogen bonding
- surface tension
- vapor pressure
- viscosity
- Answer
-
c. surface tension
Exercise \(\PageIndex{39}\)
Explain which substance in each of the following pairs is likely to have the higher normal melting point: (a) HCl or NaCl; (b) C2H5OC2H5 (diethyl ether) or C4H9OH (butanol); (c) CHI3 or CHF3; (d) C2H4 or CH3OH
- Answer a
-
NaCl, because it is an ionic compound not molecular
- Answer b
-
butanol due to hydrogen bonding in butanol not in diethyl ether
- Answer c
-
CHI3 because of stronger London dispersion forces
- Answer d
-
CH3OH due to hydrogen bonding
Exercise \(\PageIndex{40}\)
Explain which substance in each of the following pairs is likely to have the higher normal melting point: (a) H2S or H2O; (b) NH3 or PH3; (c) KBr or CH3Br; (d) CH4 or SiH4.
- Answer a
-
H2O because hydrogen bonding is stronger than dipole-dipole bonds
- Answer b
-
NH3 because hydrogen bonding can occur with 2 of the molecules
- Answer c
-
KBr due to being an ionic compound not molecular
- Answer d
-
SiH4 due to stronger intermolecular forces and electrons
Exercise \(\PageIndex{41}\)
Predict the shapes of each of the following molecules and identify the member of each pair with the higher boiling point using VESPR models: (a) PBr3 or PF3; (b) SO2 or CO2; (c) BF3 or BCl3.
- Answer a
-
PBr3 due to stronger dipole-dipole bonds
- Answer b
-
SO2 due to dipole-dipole bonds being stronger than London dispersion forces
- Answer c
-
BCl3 has stronger van der Waal's forces
Exercise \(\PageIndex{42}\)
Determine which liquid in each of the following pairs has the greater surface tension: (a) cis-dichloroethene or trans-dichloroethene; (b) benzene at 20°C or benzene at 60°C.
- Answer a
-
cis-dichloroethene due to the molecule being polar and having both dipole-dipole and van der Waals forces
- Answer b
-
benzene at 20°C due to stronger intermolecular forces at a cooler temperature
Exercise \(\PageIndex{43}\)
Rank the following molecules in order of increasing viscosity at 50°C: C6H5SH, C6H5OH, C6H6.
- Answer
-
C6H6 < C6H5SH < C6H5OH
Exercise \(\PageIndex{44}\)
The boiling point of chloroform (CHCl3) is lower than that of carbon tetrachloride (CCl4). Since chloroform is polar and carbon tetrachloride is not, with consideration of the dipole-dipole forces would predict that chloroform would have the higher boiling point. How can we account for the observed order of the boiling points?
- Answer
-
Carbon tetrachloride has a higher boiling point because the dispersion forces are extensive enough to be stronger than the dipole-permanent dipole interactions in chloroform.