The document contains a set of practice questions about intermolecular forces and interactions between particles. It discusses topics like how intermolecular forces affect boiling points, vapor pressure, solubility, and phase changes. For each question, it provides the question text and the identified correct answer. The questions assess understanding of concepts such as hydrogen bonding, polarity, dispersion forces, and how properties depend on factors like molecular size, weight, and electronegativity differences.

1. Practice Questions Interparticle attractions
Source:http://www.chem.umass.edu/genchem/chem112/MCQ_Intermolecular_Forces.htm
Intermolecular Forces Sample Questions
1. The boilingpointof water is about200°C higher than one would predict from the boilingpoints of hydrogen
sulfideand hydrogen selenide. One may explain this apparentanomaly by which of the foll owing?
Water has the lowest molecular weight.
The H-O covalent bond is much stronger than the H-S and H-Se bonds.
The intermolecular attractiveforces aremuch greater in water than in hydrogen sulfideand hydrogen
selenide.
The water molecule is lighter than the other two molecules.
Water is less polar than hydrogen sulfideand hydrogen selenide.
2. The vapor pressureof a liquid increases exponentially with increasingtemperature chiefly because:
the fraction of high energy molecules increases much faster than the average energy.
the strength of the intermolecular forces increases.
the average molecular mass increases.
the enthalpy of vaporization increases.
atmospheric pressureincreases.
3. Molecular iodinewould be most soluble in:
water
carbon tetrachloride
vodka (ethanol and water)
equally solublein all four
vinegar (acetic acid and water)
4. At room temperature, F2 and Cl2 are gases,Br2 is a liquid,and I2 is a solid.This is because:
polarity increases with molecular size.
dipole-induced dipoleinteractions increasewith molecular size.
dipole-dipoleinteractionsincreasewith molecular size.
dispersion interactions increasewith molecular size.
dispersion interactions increasewith molecular sizeand polarity increases with molecular size.
5. Which of the followingbest explains why the normal melting point of ICl(27.2°C) is so much higher than that
of Br2 (-7.2°C). The molecules of both substances havethe same number of electrons.

2. the ICl molecules undergo hydrogen bonding
ICl molecules arepolar
the Cl atom in the ICl moleculeis more polarizablethan the Br atom in the Br2 molecule.
the ICl molecules have a lower molecular weight
iodinein ICl is more electronegative than bromine in Br2
6. Why is the normal boilingpointof hydrogen fluorideis so much higher than that of hydrogen chloride,the
hydrideof the next element in group VIIA?
the electron cloud in the HF moleculeis more easily distorted (i.e. is more polarizable) than that of HCl.
the HF molecules undergoes a higher degree of hydrogen bondingthan HCl.
the HF molecules have a lower dipolemoment.
chlorinein HCl is more electronegative than fluorinein HF.
HCl molecules arenon-polar.
7. The boilingpointof CH4 is much lower than that of HF. This is because:
of dipole-dipoleinteractions in CH4.
of hydrogen bondingin HF.
HF is more polarizable.
of ion-dipoleinteractions in CH4.
CH4 is polar.
8. Which one of the followingmolecules would be most polar?
H2
HCl
HBr
HF
HI
9. For a given substance,which of the followingphasetransitionsshould RELEASE the most energy.
Solid to liquid
Solid to gas
Gas to liquid
Gas to solid
Liquid to gas

3. 10. One of the reasons thatsolid CuSO4 dissolves in water is:
the ion-dipoleforces between the ions and the water molecules
instantaneous dipole-induced dipoleforces (dispersion or London forces) between the Cu2+and the SO4
2-
ions
the electrostatic force of attraction between the Cu2+ and the SO4
2- ions
the hydrogen bondingbetween the water molecules
instantaneous dipole-induced dipoleforces (dispersion or London forces) between the water molecules
11. The concept of "likedissolves like"is illustrated by which of the following?
I2(s) is moresolublein CCl4 than in water.
CuSO4(s) is more solublein CCl4 than in water.
CCl4 is solublein water.
I2(s) is moresolublein water than in CCl4.
NaCl (s) is more solublein CCl4 than in water.
12. A soluteis most likely to be highly solublein a solventif the soluteis _____ and the solvent is ______.
ionic or polar,non-polar
ionic or polar,polar
non-polar,polar
non-polar,ionic
13. Based on the followinginformation:
CF4, Molecular Weight87.99, Normal BoilingPoint -182°C
CCl4,Molecular Weight153.8, Normal BoilingPoint -123°C
Which of the above substances would have the higher equilibriumvapor pressureassumingthatboth
substances arein the liquid stateatthe same temperature?
CF4 and CCl4 would have the same vapor pressure
CF4
CCl4
impossibleto determine from the information given
14. State why the normal melting pointof ICl(27.2°C) is so much higher than that of Br2 (-7.2°C). The molecules
of both substances havethe same number of electrons.
the Cl atom in the ICl moleculeis more polarizablethan the Br atom in the Br2 molecule.
the ICl molecules undergo hydrogen bonding
the ICl molecules have a lower molecular weight

4. ICl molecules arepolar
iodinein ICl is more electronegative than bromine in Br2
15. Based on the followinginformation:
CF4, Molecular Weight87.99, Normal BoilingPoint -182°C
CCl4,Molecular Weight153.8, Normal BoilingPoint -123°C
The intermolecular forces of attraction in the above substances is described by which of the following:
ion-dipoleforces
dipole-dipoleforces (permanent dipoles)
dispersion (or London) forces
gravitational forces
repulsiveforces
16. Based on the followinginformation:
CF4, Molecular Weight87.99, Normal BoilingPoint -182°C
CCl4,Molecular Weight153.8, Normal BoilingPoint -123°C
The reason that CCl4 has a higher boilingpointthan CF4 is that:
CCl4 molecules have a greater polarizability
CF4 molecules are more polar
CCl4 molecules aremore polar
CF4 moleculehave a greater polarizability
17. Solid iodinewould be most solublein which of the followingsolvents?
iodinewould be equally solublein water and carbon tetrachloride
iodinewould be insolublein both water and carbon tetrachloride
water
carbon tetrachloride
impossibleto determine the relativesolubilities

5. Answers
1.The boilingpoint ofwater isabout 200°C higherthan one would predictfrom the boilingpointsof
hydrogensulfide and hydrogenselenide.One mayexplainthis apparent anomaly by which of the
following?
The right answerwas... The intermolecularattractive forcesare muchgreaterinwaterthan inhydrogen
sulfide andhydrogenselenide.
2.The vapor pressure of a liquidincreasesexponentiallywithincreasingtemperature chieflybecause:
The right answerwas... the fractionof highenergymoleculesincreases muchfasterthanthe average
energy.
3.Moleculariodine wouldbe most soluble in:
The right answerwas... carbontetrachloride
4.At room temperature,F2 and Cl2 are gases, Br2 is a liquid,andI2 is a solid.This isbecause:
The right answerwas... dispersioninteractionsincrease withmolecularsize.
5.Whichof the followingbestexplainswhythe normal meltingpoint ofICl(27.2°C) is so much higher
than that of Br2 (-7.2°C). The moleculesofboth substanceshave the same number ofelectrons.
The right answerwas... ICl moleculesare polar
6.Why is the normal boilingpoint of hydrogenfluoride isso much higherthan that of hydrogen
chloride,the hydride of the nextelementingroup VIIA?
The right answerwas... the HF moleculesundergoesahigher degree of hydrogenbondingthanHCl.
7.The boilingpoint ofCH4 is much lower than that of HF. This is because:
The right answerwas... of hydrogenbondinginHF.
8.Whichone of the followingmoleculeswouldbe most polar?
The right answerwas... HF
9.For a givensubstance,which of the followingphase transitionsshould RELEASE the most energy.
The right answerwas... Gas to solid
10.One of the reasonsthat solidCuSO4 dissolvesinwater is:
The right answerwas... the ion-dipole forcesbetweenthe ionsandthe watermolecules
11.The conceptof "like dissolveslike" isillustratedbywhich ofthe following?
The right answerwas... I2(s) ismore soluble inCCl4 thaninwater.
12.A solute is most likelyto be highlysoluble in a solventif the solute is _____ and the solventis
______.
The right answerwas... ionicorpolar,polar

6. 13.Based on the followinginformation:
CF4,MolecularWeight87.99, Normal BoilingPoint -182°C
CCl4,MolecularWeight153.8, Normal BoilingPoint -123°C
Whichof the above substances wouldhave the higherequilibriumvaporpressure assuming that both
substancesare inthe liquidstate at the same temperature?
The right answerwas... CF4
State why the normal meltingpointof ICl(27.2°C) is so much higherthan that of Br2 (-7.2°C). The
moleculesofboth substanceshave the same number of electrons.
The right answerwas... ICl moleculesare polar
15.Based on the followinginformation:
CF4,MolecularWeight87.99, Normal BoilingPoint -182°C
CCl4,MolecularWeight153.8, Normal BoilingPoint -123°C
.The intermolecularforcesofattraction in the above substances isdescribedby which of the
following:
The right answerwas... dispersion(orLondon) forces
16.Based on the followinginformation:
CF4,MolecularWeight87.99, Normal BoilingPoint-182°C
CCl4,MolecularWeight153.8, Normal BoilingPoint -123°C
.The reason that CCl4 has a higherboilingpoint than CF4 is that:
The right answerwas... CCl4 moleculeshave agreaterpolarizability
17.Solid iodine wouldbe most soluble inwhich of the followingsolvents?
The right answerwas... carbontetrachloride