Question 1

Which of the following molecules would you expect to have the highest molecular dipole moment, based on both bond polarity and molecular geometry?

Accepted Answer

Chloroform ($\mathrm{CHCl_3}$)

Question 2

A student is comparing the boiling points of n-pentane, isopentane, and neopentane. Which statement best explains why n-pentane has the highest boiling point?

Accepted Answer

n-Pentane has the greatest surface area, leading to stronger London dispersion forces.

Question 3

Which of the following intermolecular forces is primarily responsible for the high boiling point of methanol ($\mathrm{CH_3OH}$) compared to dimethyl ether ($\mathrm{CH_3OCH_3}$)?

Accepted Answer

Hydrogen bonding

Question 4

Given the following bonds, which has the largest bond dipole moment? 
$\mathrm{H-F}$, $\mathrm{H-Cl}$, $\mathrm{H-Br}$, $\mathrm{H-I}$

Accepted Answer

$\mathrm{H-F}$

Question 5

Which of the following molecules can form hydrogen bonds with water, and why?

Accepted Answer

Methanol ($\mathrm{CH_3OH}$), because it has an O-H group.

Question 6

A nonpolar solute is added to water. What is the most likely outcome, and why?

Accepted Answer

The nonpolar solute will not dissolve because it cannot disrupt the hydrogen bonding network of water.

Question 7

Which of the following statements about London dispersion forces is correct?

Accepted Answer

They are stronger in molecules with larger, more polarizable atoms.

Question 8

Which molecule would have the lowest boiling point, and why?
A. n-pentane
B. isopentane
C. neopentane

Accepted Answer

Neopentane, because it is the most highly branched and has the smallest surface area.

Question 9

Which of the following best describes the relationship between bond dipole moment ($\mu$), charge separation ($\delta$), and bond length ($d$)?

Accepted Answer

$\mu = \delta 	imes d$

Question 10

Why does cis-1,2-dibromomethene have a molecular dipole moment while trans-1,2-dibromomethene does not?

Accepted Answer

The trans isomer has a symmetrical arrangement that cancels out the dipole moments.

Question 11

Which of the following compounds would be most soluble in water?

Accepted Answer

Methanol ($\mathrm{CH_3OH}$)

Question 12

A student mixes ethylamine ($\mathrm{CH_3CH_2NH_2}$) and methanol ($\mathrm{CH_3OH}$). Which will have stronger hydrogen bonding and why?

Accepted Answer

Methanol, because O-H bonds are more polar than N-H bonds.

Question 13

Which of the following is a correct statement about dipole-dipole interactions?

Accepted Answer

They are strongest when the positive end of one molecule is near the negative end of another.

Question 14

Which of the following best explains why polar solutes dissolve in polar solvents?

Accepted Answer

Polar solvents can break the intermolecular forces in polar solutes, increasing entropy.

Question 15

Which of the following molecules has a zero molecular dipole moment due to its geometry?

Accepted Answer

Carbon tetrachloride ($\mathrm{CCl_4}$)

Question 16

Which of the following statements about hydrogen bonding is correct?

Accepted Answer

Hydrogen bonding requires N-H or O-H groups.

Question 17

A molecule has lone pairs on its central atom and polar bonds. Which factor will increase its molecular dipole moment?

Accepted Answer

Increasing the bond angle so that dipoles add constructively

Question 18

Which of the following is the best explanation for why neopentane has a lower boiling point than n-pentane?

Accepted Answer

Neopentane has a smaller surface area, resulting in weaker London dispersion forces.

Question 19

Which of the following molecules would be expected to have the strongest London dispersion forces?

Accepted Answer

Hexane ($\mathrm{C_6H_{14}}$)

Question 20

Which of the following is true regarding the solubility of a polar solute in a nonpolar solvent?

Accepted Answer

The polar solute will not dissolve because the solvent cannot break the solute's intermolecular forces.

Acids, Bases, Functional Groups, and Intermolecular Forces in Organic Chemistry

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