Q: Arrange the following compounds in order of increasing strength of intermolecular forces: Br$_2$, I$_2$, NH(CH$_3$)$_2$

I$_2$ < Br$_2$ < NH(CH$_3$)$_2$

Q: Identify the type of force involved in the following situations as either intramolecular or intermolecular: (i) Boiling of water (ii) Formation of H$_2$O in a fuel cell through the combination of H$_2$ and O$_2$ (iii) Vulcanization covalently bonds the rubber in tire (iv) Coffee dissolves in water (v) Liquid flowing in a narrow space due to capillary action

i. intermolecular, ii. intramolecular, iii. intramolecular, iv. intermolecular, v. intermolecular

Q: How are vapor pressure and boiling point affected by stronger intermolecular forces?

Stronger intermolecular forces decrease the vapor pressure and increase the boiling point.

Q: A liquid with weak intermolecular forces will have which of the following properties? (i) Low surface tension (ii) High viscosity (iii) High boiling point (iv) High vapor pressure

i. Weak, ii. Weak, iii. Weak, iv. Strong

Q: Which of the following statements is true regarding the boiling point of a substance with strong intermolecular forces?

It will have a higher boiling point compared to a substance with weak intermolecular forces.

Q: Which of the following best describes the effect of molecular geometry on dipole moment?

Molecular geometry can cause individual bond dipoles to cancel out, resulting in a nonpolar molecule.

Q: Which of the following molecules is polar? (i) H$_2$Se (ii) Bi$_2$ (iii) CH$_3$F (iv) NFCI$_2$

i. H$_2$Se, iii. CH$_3$F, iv. NFCI$_2$

Question 1

Which of the following molecules has a net dipole moment? Justify your answer based on molecular geometry and electronegativity differences.
(i) AsCl$_3$
(ii) SF$_6$
(iii) CH$_2$F$_2$
(iv) SeCl$_4$

Accepted Answer

Only (i) AsCl$_3$ and (iii) CH$_2$F$_2$ have net dipole moments due to their trigonal pyramidal and tetrahedral geometry, respectively.

Question 2

Which of the following best explains why water (H$_2$O) is a polar molecule?

Accepted Answer

Oxygen is covalently bonded to two hydrogen atoms and the molecule has a bent geometry.

Question 3

Which statement(s) correctly describe hydrogen bonding between H$_2$O molecules?

Accepted Answer

The partial negative charge of oxygen attracts the partial positive charge on hydrogen in another molecule.

Question 4

Arrange the following compounds in order of increasing strength of intermolecular forces:
Br$_2$, I$_2$, NH(CH$_3$)$_2$

Accepted Answer

I$_2$ < Br$_2$ < NH(CH$_3$)$_2$

Question 5

Identify the type of force involved in the following situations as either intramolecular or intermolecular:
(i) Boiling of water
(ii) Formation of H$_2$O in a fuel cell through the combination of H$_2$ and O$_2$
(iii) Vulcanization covalently bonds the rubber in tire
(iv) Coffee dissolves in water
(v) Liquid flowing in a narrow space due to capillary action

Accepted Answer

i. intermolecular, ii. intramolecular, iii. intramolecular, iv. intermolecular, v. intermolecular

Question 6

How are vapor pressure and boiling point affected by stronger intermolecular forces?

Accepted Answer

Stronger intermolecular forces decrease the vapor pressure and increase the boiling point.

Question 7

Which compound would have the highest viscosity?
(a) CF$_4$
(b) CH$_2$Br$_2$
(c) HOCH$_2$OH

Accepted Answer

Compound c (HOCH$_2$OH)

Question 8

Which of the following molecules is nonpolar?
(i) H$_2$Se
(ii) Bi$_2$
(iii) CH$_3$F
(iv) NFCI$_2$

Accepted Answer

ii. Bi$_2$

Question 9

Which intermolecular force is the strongest in HOCH$_2$OH?

Accepted Answer

Hydrogen bonding

Question 10

A liquid with weak intermolecular forces will have which of the following properties?
(i) Low surface tension
(ii) High viscosity
(iii) High boiling point
(iv) High vapor pressure

Accepted Answer

i. Weak, ii. Weak, iii. Weak, iv. Strong

Question 11

Which property is most directly affected by the strength of hydrogen bonding in a liquid?
(a) Molar heat of vaporization
(b) Melting point
(c) Vapor pressure
(d) Viscosity

Accepted Answer

a) Molar heat of vaporization

Question 12

Which of the following statements is true regarding the boiling point of a substance with strong intermolecular forces?

Accepted Answer

It will have a higher boiling point compared to a substance with weak intermolecular forces.

Question 13

Which of the following best describes the effect of molecular geometry on dipole moment?

Accepted Answer

Molecular geometry can cause individual bond dipoles to cancel out, resulting in a nonpolar molecule.

Question 14

Which of the following molecules would you expect to have the highest melting point?
(a) CF$_4$
(b) CH$_2$Br$_2$
(c) HOCH$_2$OH

Accepted Answer

Compound c (HOCH$_2$OH)

Question 15

Which of the following is a consequence of strong hydrogen bonding in water?

Accepted Answer

High surface tension

Question 16

Which intermolecular force is present in CF$_4$?

Accepted Answer

London dispersion forces

Question 17

Which of the following molecules is polar?
(i) H$_2$Se
(ii) Bi$_2$
(iii) CH$_3$F
(iv) NFCI$_2$

Accepted Answer

i. H$_2$Se, iii. CH$_3$F, iv. NFCI$_2$

Question 18

Which of the following best describes the relationship between vapor pressure and intermolecular forces?

Accepted Answer

Vapor pressure decreases as intermolecular forces increase.

Question 19

Which of the following is NOT a consequence of strong intermolecular forces in a liquid?

Accepted Answer

Low boiling point

Ch.11 – Liquids, Solids, and Intermolecular Forces: Molecular Polarity and Intermolecular Forces

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