Question 1

Based on the following information, which compound has the strongest intermolecular forces? Substance ΔH_vap(kJ/mol) Argon (Ar)6.3 Benzene (C₆H₆)31.0 Ethanol (C₂H₅OH)39.3 Water (H₂O)40.8 Methane (CH₄)9.2 A)Argon B)Benzene C)Ethanol D)Water E)Methane

Accepted Answer

The compound with the strongest intermolecular forces will have the highest ΔH_vap value. Water has the highest value of 40.8 kJ/mol, indicating that it has the strongest intermolecular forces.

Question 2

Viscosity is __________.
A)the "skin" on a liquid surface caused by intermolecular attraction
B)the resistance to flow
C)the same as density
D)inversely proportional to molar mass
E)unaffected by temperature

Accepted Answer

Viscosity is the resistance to flow of a liquid due to the internal friction between molecules. It is not the same as density (C) and is not inversely proportional to molar mass (D). It can be affected by temperature (E), with most liquids having lower viscosity at higher temperatures. The "skin" on a liquid surface caused by intermolecular attraction is called surface tension, not viscosity (A).

Question 3

The critical temperature and pressure of CS₂ are 279°C and 78 atm, respectively. At temperatures above 279°C and pressures above 78 atm, CS₂ can only occur as a __________. A)solid B)liquid C)liquid and gas D)gas E)supercritical fluid

Accepted Answer

Above the critical temperature and pressure, CS₂ cannot exist as a liquid or gas in their separate states. It instead exists as a supercritical fluid, which exhibits properties of both a liquid and a gas.

Question 4

Of the following, __________ is the most volatile. A)CBr₄ B)CCl₄ C)CF₄ D)CH₄ E)C₆H₁₄

Accepted Answer

Methane (CH₄) is the most volatile because it has the lowest molecular weight and weakest intermolecular forces (London dispersion forces) among the given options, leading to a higher tendency to vaporize.

Question 5

What types of intermolecular forces exist between NH₃ and CBr₄? A)dispersion forces and dipole-dipole forces B)dispersion forces and dipole-induced dipole forces C)dispersion forces and hydrogen bonds D)dispersion forces, hydrogen bonds, and induced dipole-induced dipole forces E)dispersion forces, hydrogen bonds, and dipole-induced dipole forces

Accepted Answer

NH3 is polar and can induce a dipole in the nonpolar CBr4, leading to dipole-induced dipole forces, along with dispersion forces present in all molecules.

Question 6

Which statements about viscosity are true? (i)Viscosity increases as temperature decreases.
(ii)Viscosity increases as molecular weight increases.
(iii)Viscosity increases as intermolecular forces increase.
A)(i)only
B)(ii)and (iii)
C)(i)and (iii)
D)none
E)all

Accepted Answer

Viscosity is influenced by temperature, molecular weight, and intermolecular forces. As temperature decreases, molecules move slower and have more interactions, increasing viscosity. Higher molecular weight means larger molecules, which typically interact more strongly and move more slowly relative to each other, increasing viscosity. Stronger intermolecular forces also lead to increased resistance to flow, hence higher viscosity.

Question 7

How high a liquid will rise up a narrow tube as a result of capillary action depends on __________.
A)the magnitudes of cohesive forces in the liquid and adhesive forces between the liquid and the tube, and gravity
B)gravity alone
C)only the magnitude of adhesive forces between the liquid and the tube
D)the viscosity of the liquid
E)only the magnitude of cohesive forces in the liquid

Accepted Answer

The height a liquid will rise up a narrow tube is determined by the balance of cohesive forces within the liquid and adhesive forces between the liquid and the tube, as well as the influence of gravity. This phenomenon, known as capillary action, occurs when the adhesive forces between the liquid and the tube are greater than the cohesive forces within the liquid. The height to which the liquid rises is inversely proportional to the diameter of the tube and directly proportional to the magnitude of the adhesive forces between the liquid and tube. Therefore, choice A is the best answer as it takes into account all of these factors.

Question 8

A substance that expands to fill its container yet has a density approaching that of a liquid, and that can behave as a solvent is called a(n)__________.
A)plasma
B)gas
C)liquid
D)amorphous solid
E)supercritical fluid and gas

Accepted Answer

A supercritical fluid and gas is a substance that is above its critical temperature and pressure, which allows it to have properties of both a gas and a liquid, including the ability to behave as a solvent. Despite its gas-like behavior, it has a density that approaches that of a liquid.

Question 9

The phase changes B → C and D → E are not associated with temperature increases because the heat energy is used up to __________.
A)increase distances between molecules
B)break intramolecular bonds
C)rearrange atoms within molecules
D)increase the velocity of molecules
E)increase the density of the sample

Accepted Answer

The answer of The phase changes B → C and...

Question 10

Which compound has the strongest intermolecular forces? A)CBr₄ B)C₁₂H₂₆ C)CI₄ D)N₂ E)O₂

Accepted Answer

The answer of Which compound has the strongest intermolecular forces? A)CBr₄ B)C₁₂H₂₆ C)CI₄ D)N₂ E)O₂...

Question 11

Which of the following statements is false?
A)The absolute value of the heat of sublimation is equal to the absolute value of the heat of deposition.
B)The heat of sublimation is equal to the sum of the heat of vaporization and the heat of melting.
C)The heat of sublimation is equal to the sum of the heat of vaporization and the heat of freezing.
D)The absolute value of the heat of sublimation is equal to the absolute value of the sum of the heat of condensation and the heat of freezing.
E)The absolute value of the heat of deposition is equal to sum of the absolute value of the heat of vaporization and the absolute value of the heat of freezing.

Accepted Answer

The heat of sublimation is equal to the sum of the heat of vaporization (energy required to vaporize a substance) and the heat of sublimation (energy required to convert a substance from a solid to a gas), whereas the heat of freezing is the energy released when a substance changes from a liquid to a solid. Therefore, statement C is false as it incorrectly adds the heat of freezing instead of the heat of sublimation.

Question 12

Of the following, __________ is an exothermic process.
A)melting
B)subliming
C)freezing
D)boiling
E)All of the above are exothermic.

Accepted Answer

Freezing is an exothermic process because it releases heat as it changes from a liquid to a solid state. Melting, subliming, and boiling are endothermic processes because they require the input of heat to occur.

Question 13

__________ is the energy required to expand the surface area of a liquid by a unit amount of area.
A)Viscosity
B)Surface tension
C)Volatility
D)Meniscus
E)Capillary action

Accepted Answer

The energy required to expand the surface area of a liquid by a unit amount of area is known as surface tension. Therefore, option B is the correct answer. Viscosity is the measure of a fluid's resistance to flow, volatility is the tendency of a liquid to vaporize, meniscus is the curved surface of a liquid in a container, and capillary action is the movement of a liquid along a narrow tube or porous material due to intermolecular forces. None of these options refer to the energy required to expand the surface area of a liquid.

Question 14

Heat of sublimation can be approximated by adding together __________ and __________.
A)heat of fusion, heat of condensation
B)heat of fusion, heat of vaporization
C)heat of freezing (solidification), heat of condensation
D)heat of freezing (solidification), heat of vaporization
E)heat of deposition, heat of vaporization

Accepted Answer

The heat of sublimation is the energy required to change a substance from solid to gas phase directly. This process can be thought of as occurring in two steps: first, the solid melts to a liquid (heat of fusion), and then the liquid vaporizes to a gas (heat of vaporization). Adding the heat of fusion and the heat of vaporization gives an approximation of the heat of sublimation.

Question 15

Large intermolecular forces in a substance are manifested by __________.
A)low vapor pressure
B)high boiling point
C)high heats of fusion and vaporization
D)high critical temperatures and pressures
E)all of the above

Accepted Answer

All of the above options are manifestations of large intermolecular forces. Low vapor pressure means that molecules are strongly attracted to each other, making it difficult for them to escape into the gas phase. High boiling points also reflect strong intermolecular forces because more energy is required to break the bonds between molecules and convert the substance into the gas phase. High heats of fusion and vaporization are likewise indicative of strong intermolecular forces, as they require significant energy to overcome the attractions between molecules. Finally, high critical temperatures and pressures reflect strong intermolecular forces because it takes a lot of energy to break the bonds between molecules at those conditions.

Question 16

The property responsible for the "beading up" of water is __________.
A)density
B)viscosity
C)vapor pressure
D)surface tension
E)hydrogen bonding

Accepted Answer

Surface tension is the property responsible for the "beading up" of water. This is because water molecules are attracted to each other through hydrogen bonding, which creates a surface film that holds the water droplets together, creating surface tension.

Question 17

What types of intermolecular forces exist between PH₃ and N₂? A)dispersion forces and dipole-dipole forces B)dispersion forces and dipole-induced dipole forces C)dispersion forces and hydrogen bonds D)dispersion forces, hydrogen bonds, and induced dipole-induced dipole forces E)dispersion forces, hydrogen bonds, and dipole-induced dipole forces

Accepted Answer

PH3 is a polar molecule, and N2 is nonpolar. The interaction between them involves dispersion forces and dipole-induced dipole forces.

Question 18

The shape of a liquid's meniscus is determined by __________.
A)the viscosity of the liquid
B)the type of material the container is made of
C)the relative magnitudes of cohesive forces in the liquid and adhesive forces between the liquid and its container
D)the amount of hydrogen bonding in the liquid
E)the volume of the liquid

Accepted Answer

The shape of a liquid's meniscus is determined by the relative magnitudes of cohesive forces in the liquid and adhesive forces between the liquid and its container. Cohesive forces between the liquid molecules tend to make the liquid surface concave, while adhesive forces between the liquid and container tend to make the liquid surface convex. The balance between these two forces determines the shape of the meniscus. The viscosity of the liquid, the type of material the container is made of, the amount of hydrogen bonding in the liquid, and the volume of the liquid do not significantly affect the shape of the meniscus.

Question 19

The substance with the largest heat of vaporization is __________. A)I₂ B)Br₂ C)Cl₂ D)F₂ E)O₂

Accepted Answer

The answer of The substance with the largest heat of...

Question 20

Of the following, __________ should have the highest critical temperature. A)CBr₄ B)CCl₄ C)CF₄ D)CH₄ E)H₂

Accepted Answer

The answer of Of the following, __________ should have the...

Quiz 11: Liquids and Intermolecular Forces

Based on the following information, which compound has the strongest intermolecular forces? Substance ΔH_vap(kJ/mol) Argon (Ar) 6.3 Benzene (C₆H₆) 31.0 Ethanol (C₂H₅OH) 39.3 Water (H₂O) 40.8 Methane (CH₄) 9.2

Viscosity is __________.

The critical temperature and pressure of CS₂ are 279°C and 78 atm, respectively. At temperatures above 279°C and pressures above 78 atm, CS₂ can only occur as a __________.

Of the following, __________ is the most volatile.

What types of intermolecular forces exist between NH₃ and CBr₄?

Which statements about viscosity are true? (i) Viscosity increases as temperature decreases. (ii) Viscosity increases as molecular weight increases. (iii) Viscosity increases as intermolecular forces increase.

How high a liquid will rise up a narrow tube as a result of capillary action depends on __________.

A substance that expands to fill its container yet has a density approaching that of a liquid, and that can behave as a solvent is called a(n) __________.

The phase changes B → C and D → E are not associated with temperature increases because the heat energy is used up to __________.

Which compound has the strongest intermolecular forces?

Which of the following statements is false?

Of the following, __________ is an exothermic process.

__________ is the energy required to expand the surface area of a liquid by a unit amount of area.

Heat of sublimation can be approximated by adding together and .

Large intermolecular forces in a substance are manifested by __________.

The property responsible for the "beading up" of water is __________.

What types of intermolecular forces exist between PH₃ and N₂?

The shape of a liquid's meniscus is determined by __________.

The substance with the largest heat of vaporization is __________.

Of the following, __________ should have the highest critical temperature.