Question 1

Which of the following intermolecular forces is primarily responsible for the unusually high boiling point of water ($H_2O$)?

Accepted Answer

Hydrogen bonding

Question 2

A sample of ethanol ($C_2H_5OH$) is compared to a sample of dimethyl ether ($CH_3OCH_3$), both of which have the same molecular formula. Ethanol has a much higher boiling point. Which statement best explains this observation?

Accepted Answer

Ethanol forms hydrogen bonds, while dimethyl ether does not.

Question 3

Which of the following substances would you expect to have the highest heat of vaporization, assuming similar molar masses?

Accepted Answer

Ammonia ($NH_3$)

Question 4

Which equation is used to relate the vapor pressure of a liquid to its temperature, allowing the calculation of the heat of vaporization?

Accepted Answer

$\ln \left( \frac{P_2}{P_1} \right) = -\frac{\Delta H_{vap}}{R} \left( \frac{1}{T_2} - \frac{1}{T_1} \right)$

Question 5

Which of the following best describes the physical property of surface tension?

Accepted Answer

The energy required to increase the surface area of a liquid due to intermolecular forces.

Question 6

A liquid with strong intermolecular forces will generally have which of the following properties?

Accepted Answer

High boiling point and low vapor pressure

Question 7

Which of the following phase changes is endothermic?

Accepted Answer

Sublimation

Question 8

Given the following heating curve for water, which segment represents the phase change from liquid to gas?

Accepted Answer

The flat segment at $100^\circ C$

Question 9

Which of the following best describes the triple point on a phase diagram?

Accepted Answer

The temperature and pressure at which all three phases (solid, liquid, gas) coexist in equilibrium.

Question 10

A sample of water is heated from $-10^\circ C$ to $110^\circ C$. Which equation would you use to calculate the energy required to convert $10.0\ g$ of ice at $-10^\circ C$ to steam at $110^\circ C$?

Accepted Answer

Use $q = mc\Delta T$ for each segment and add the heats of fusion and vaporization.

Question 11

Which of the following statements about phase diagrams is correct?

Accepted Answer

The critical point marks the highest temperature at which a liquid can exist.

Question 12

Which of the following substances would exhibit capillary action in a glass tube due to strong adhesive forces?

Accepted Answer

Water

Question 13

Which of the following is NOT a type of intermolecular force?

Accepted Answer

Ionic bonding

Question 14

If the vapor pressure of a liquid increases with temperature, which equation best describes this relationship?

Accepted Answer

$\ln P = -\frac{\Delta H_{vap}}{R} \frac{1}{T} + C$

Question 15

Which of the following best explains why oil and water do not mix?

Accepted Answer

Oil molecules are nonpolar and interact only via London dispersion forces, while water molecules are polar and interact via hydrogen bonding.

Question 16

Which of the following would increase the boiling point of a liquid?

Accepted Answer

Increasing the strength of intermolecular forces

Question 17

A phase diagram for carbon dioxide shows that at 1 atm, solid $CO_2$ sublimes directly to gas. What does this indicate about the triple point of $CO_2$?

Accepted Answer

The triple point occurs at a pressure higher than 1 atm.

Question 18

Which of the following is the best example of a real-life application of the Clausius-Clapeyron equation?

Accepted Answer

Predicting the boiling point of water at the summit of Mount Everest.

Question 19

Which of the following statements about heating curves is correct?

Accepted Answer

The temperature remains constant during a phase change.

Question 20

Which of the following best describes the process of condensation?

Accepted Answer

A gas changes to a liquid, releasing energy to the surroundings.

Intermolecular Forces, Phase Changes, and Properties of Liquids and Solids

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