Intermolecular Forces Practice Exam Answers

Name: _________________
Intermolecular Forces Practice Exam
Date: _________
1. At STP, fluorine is a gas and bromine is a liquid because, 8. Hydrogen bonding is a type of
compared to fluorine, bromine has
1) strong covalent bond
1) stronger covalent bonds
2) weak ionic bond
2) stronger intermolecular forces
3) strong intermolecular force
3) weaker covalent bonds
4) weak intermolecular force
4) weaker intermolecular forces
9. In which liquid is hydrogen bonding strongest?
2. Which statement explains why low temperature and high
1) HF( )
2) H2( )
pressure are required to liquefy chlorine gas?
3) CH 4( )
4) NH 3( )
1) Chlorine molecules have weak covalent bonds.
10. Which kinds of bonds are found in a sample of 2) Chlorine molecules have strong covalent bonds.
liquid H2O?
3) Chlorine molecules have weak intermolecular
forces of attraction.
1) covalent bonds, only
4) Chlorine molecules have strong intermolecular
2) hydrogen bonds, only
forces of attraction.
3) both covalent and hydrogen bonds
4) both ionic and hydrogen bonds
3. Molecules in a sample of NH ( ) are held closely
3
together by intermolecular forces
1)
2)
3)
4)
existing between ions
existing between electrons
caused by different numbers of neutrons
caused by unequal charge distribution
4. Which of these substances has the strongest
intermolecular forces?
1) H 2O
2) H2S
3) H2Se
4) H2Te
5. In aqueous solution, a chloride ion is attracted to which
end of the water molecule?
1)
2)
3)
4)
the hydrogen end, which is the positive pole
the hydrogen end, which is the negative pole
the oxygen end, which is the positive pole
the oxygen end, which is the negative pole
6. At 50.°C and standard pressure, intermolecular forces of
attraction are strongest in a sample of
1) ethanoic acid
3) propanone
2) ethanol
4) water
7. At standard pressure, CH4 boils at 112 K and H2O boils
at 373 K. What accounts for the higher boiling point of H
2 O at standard pressure?
1) covalent bonding
3) hydrogen bonding
2) ionic bonding
4) metallic bonding
11. Based on intermolecular forces, which of these
substances would have the highest boiling point?
1) He
2) O2
3) CH 4
4) NH 3
12. Using your knowledge of chemistry and the
information in Reference Table H, which statement
concerning propanone and water at 50°C is true?
1) Propanone has a higher vapor pressure and
stronger intermolecular forces than water.
2) Propanone has a higher vapor pressure and
weaker intermolecular forces than water.
3) Propanone has a lower vapor pressure and stronger
intermolecular forces than water.
4) Propanone has a lower vapor pressure and weaker
intermolecular forces than water.
13. Which statement explains why Br2 is a liquid at STP
and I 2 is a solid at STP?
1) Molecules of Br2 are polar, and molecules of I 2 are
nonpolar.
2) Molecules of I 2 are polar, and molecules of Br2 are
nonpolar.
3) Molecules of Br2 have stronger intermolecular
forces than molecules of I 2 .
4) Molecules of I2 have stronger intermolecular
forces than molecules of Br2 .
Intermolecular Forces Practice Exam
14. Which represents a sample containing molecule-ion
attractions?
1) CH 4(g)
3) H2O(g)
2) NaCl(aq)
4) Hg(l)
15. What happens when NaCl(s) is dissolved in water?
1) Cl – ions are attracted to the oxygen atoms of water
molecules.
2) Na+ ions are attracted to the oxygen atoms of
water molecules.
3) Cl – ions are repelled by the hydrogen atoms of
water molecules.
4) Na+ ions are repelled by the oxygen atoms of water
molecules.
16. In an aqueous solution of Ca(NO3) 2, which kind of
attraction exists between the solute and the solvent?
1)
2)
3)
4)
molecule-ion attraction
molecule-molecule attraction
hydrogen bond
van der Waals force
17. As the distance between two bromine molecules
increases, the magnitude of the atractive forces between
them
1) decreases
3) remains the same
2) increases
18. Intermolecular attractions strength affect a substances 1)
2)
3)
4)
nuclear charge
melting point temperature
spectral lines
chemical properties
19. The strongest attractions exist between molecules of...?
(Hint: The mass of these elements is presented on the
Periodic Table)
1) I 2
2) Br 2
3) Cl 2
4) F2
Intermolecular Forces Practice Exam
20. Base your answer to the following question on the information below.
Carbon forms molecular compounds with some elements from Group 16. Two of these compounds
are carbon dioxide, CO2, and carbon disulfide, CS2.
Carbon dioxide is a colorless, odorless gas at room temperature. At standard temperature and
pressure, CO2(s) changes directly to CO2(g).
Carbon disulfide is formed by a direct reaction of carbon and sulfur. At room temperature, CS2 is a
colorless liquid with an offensive odor. Carbon disulfide vapors are flammable.
Compare the intermolecular forces in CO 2 and CS2 at room temperature.
21. Base your answer to the following question on the information below.
Naphthalene, a nonpolar substance that sublimes at room temperature, can be used to protect wool
clothing from being eaten by moths.
Explain, in terms of intermolecular forces, why naphthalene sublimes.
22. Base your answer to the following question on the
graph below, which shows the vapor pressure curves for
liquids A and B.
Which liquid will evaporate more rapidly? Explain your
answer in terms of intermolecular forces.
23. Base your answer to the following question on the information below and on your knowledge of chemistry.
Rubbing alcohol is a product available at most pharmacies and supermarkets. One rubbing alcohol
solution contains 2-propanol and water. The boiling point of 2-propanol is 82.3°C at standard pressure.
Explain in terms of electronegativity differences, why a C–O bond is more polar than a C–H bond.
Intermolecular Forces Practice Exam
24. Base your answer to the following question on the information below.
State evidence that indicates NH3 has stronger intermolecular forces than CF 4.
25. Base your answer to the following question on the information below.
Bond energy is the amount of energy required to break a chemical bond. The table below gives a
formula and the carbon-nitrogen bond energy for selected nitrogen compounds.
Explain, in terms of charge distribution, why a molecule of hydrogen cyanide is polar.
Base your answers to questions 26 through 28 on the table below.
27. Explain, in terms of intermolecular forces, why
hydrogen has a lower boiling point than hydrogen
bromide.
28. Explain, in terms of electronegativity difference, why
the bond in H–Cl is more polar than the bond in H–I.
26. Explain, in terms of molecular polarity, why hydrogen
chloride is more soluble than hydrogen in water under
the same conditions of temperature and pressure.
Intermolecular Forces Practice Exam
Base your answers to questions 29 and 30 on the
information below.
Each molecule listed below is formed by sharing
electrons between atoms when the atoms within the
molecule are bonded together.
Molecule A: Cl2 Molecule B: CCl4 Molecule C: NH3
29. Explain why NH 3 has stronger intermolecular forces of
attraction than Cl 2.
30. Explain why CCl4 is classified as a nonpolar molecule.
Answer Key
Intermolecular Forces Practice Test
1.
2
2.
3
3.
4
4.
1
5.
1
6.
1
7.
3
8.
3
9.
1
10.
3
11.
4
12.
2
13.
4
14.
2
15.
2
16.
1
17.
1
18.
2
19.
1
20.
21.
22.
23.
24.
25.
Examples: – Carbon
disulfide has stronger
intermolecular forces
than carbon dioxide. –
CO 2 has weaker
intermolecular forces. 26.
Acceptable responses:
Naphthalene has weak
intermolecular forces;
They are weak.
liquid A
Example:
The higher vapor
pressure of liquid A
indicates that the
intermolecular forces
between its molecules
are weaker, allowing 27.
the molecules to
escape more readily
to the vapor phase.
– There is a greater
28.
electronegativity
difference in a CO
bond than in a CH
bond. – The CO bond
is more polar because
the electronegativity
difference for a CO
29.
bond is 0.8, and the
electronegativity
difference for a CH
bond is 0.4. – The CH
bond has a smaller
difference. – The CO
is .8 and the CH is .4
Acceptable responses
include, but are not
limited to: • At
standard pressure, NH
3 has a higher boiling
point than CF 4.
30.
• The melting point of
CF4 is lower.
Examples: The
molecule has an
asymmetrical charge
distribution.; The
molecule has an
unequal distribution
of charge.
Examples: – HCl's
molecular polarity is
more similar to
water's polarity than
H2's polarity
compared to water's –
HCl and water both
polar, H 2 nonpolar,
like dissolves like –
HCl polarity is more
similar to water's
polarity
Examples: –
Hydrogen has weaker
intermolecular forces
than HBr. – hydrogen
– weaker forces.
Examples: – The
electronegativity
difference for HCl is
1.1, which is higher
than the 0.6 for HI. –
The difference for
HCl is greater.
Examples:
– NH 3 has polar
molecules that attract
each other.
– NH 3 has an
unshared pair of
electrons around the
center atom.
– NH 3 is capable of
hydrogen bonding.
– unequal distribution
of electrons — in
strong attraction
Examples:
– The molecule is
symmetrical in shape
and/or charge.
– Electrons are evenly
distributed.
– All polar covalent
dipoles cancel — no
dipole moments.
– no dipoles
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