Question 1

Of the following substances, only has London dispersion forces as its only intermolecular force.

Accepted Answer

CH₄ (methane) is a nonpolar molecule, and its only intermolecular forces are London dispersion forces. The other substances have additional intermolecular forces such as hydrogen bonding or dipole-dipole interactions.

Question 2

solids consist of atoms or molecules held together by dipole- dipole forces, London disperson forces, and/or hydrogen bonds.

Accepted Answer

The three types of intermolecular forces listed in the statement are only present in molecular solids, as they consist of discrete molecules held together by those forces. Ionic, metallic, and covalent network solids do not typically have dipole-dipole or hydrogen bonding interactions and instead rely on electrostatic or covalent bonding throughout their structures.

Question 3

The phase diagram of a substance is shown above. The area labeled indicates the gas phase for the substance.

Accepted Answer

The area labeled y indicates the gas phase for the substance.

Question 4

Which one of the following cannot form a solid with a lattice based on the sodium chloride structure?

Accepted Answer

The sodium chloride structure consists of alternating cations and anions arranged in a face-centered cubic lattice. In this structure, each cation is surrounded by anions and vice versa. CuO, RbI, LiF, and NaBr can all form a solid with this structure because they have the appropriate ion sizes and charges to fit into the lattice. However, CuClS is not a known compound and does not fit the criteria for forming a solid with the sodium chloride structure.

Question 5

Which of the following has dispersion forces as its only intermolecular force?

Accepted Answer

CH4 has only dispersion forces between its molecules. All the other options have additional intermolecular forces such as dipole-dipole or ion-dipole interactions.

Question 6

The heating curve shown was generated by measuring the heat flow and temperature for a solid as it was heated. The slope of the segment corresponds to the heat capacity of the liquid of the substance.

Accepted Answer

The segment CD is a flat line, indicating that the substance is undergoing a phase change. This means that no heat energy is being used to increase the temperature of the substance, but instead it is being used to break intermolecular bonds and convert the solid into a liquid. The slope of a flat line is zero, so the heat capacity during this phase change is also zero. Therefore, choice C is the best answer.

Question 7

Based on molecular mass and dipole moment of the five compounds in the table below, which should have the highest boiling point?

Accepted Answer

The answer of Based on molecular mass and dipole moment...

Question 8

Of the following, is the most volatile.

Accepted Answer

Methane (CH4) is the most volatile due to its small molecular size and weak intermolecular forces (London dispersion forces), leading to a low boiling point.

Question 9

Under ordinary conditions, a substance will sublime rather than melt if its triple point occurs at a pressure above atmospheric pressure.

Accepted Answer

When the triple point of a substance occurs at a pressure higher than atmospheric pressure, the substance will sublime (transition from solid to gas) rather than melt (transition from solid to liquid) because the vapor pressure of the solid phase becomes greater than the atmospheric pressure, allowing the solid to skip the liquid phase and transition directly to a gas.

Question 10

Which one of the following should have the lowest boiling point?

Accepted Answer

The answer of Which one of the following should have...

Question 11

Which of the following is not a type of solid? ionic
Molecular supercritical metallic
Covalent- network

Accepted Answer

All of the other answer choices (ionic, molecular, metallic, and covalent-network) are types of solids, while supercritical refers to a state of matter beyond a solid, liquid, or gas.

Question 12

In which of the following molecules is hydrogen bonding likely to be the most significant component of the total intermolecular forces?

Accepted Answer

Hydrogen bonding is a type of dipole-dipole interaction that occurs when hydrogen is bonded to a highly electronegative atom (such as oxygen or nitrogen). In option C, there is a hydrogen bonded to an oxygen, creating a strong hydrogen bond. None of the other options have such a strong hydrogen bond present.

Question 13

Potassium metal crystallizes in a body- centered cubic structure with a unit cell edge length of 5.31 Å. The radius of a potassium atom is Å.

Accepted Answer

The answer of Potassium metal crystallizes in a body- centered...

Question 14

Gallium crystallizes in a primitive cubic unit cell. The length of the unit cell edge is 3.70Å. The radius of a Ga atom is Å.

Accepted Answer

In a primitive cubic unit cell, the edge length is twice the radius of the atom. Therefore, the radius of a Ga atom is half of the edge length, which is 3.70 Å / 2 = 1.85 Å.

Question 15

The normal boiling point of the substance with the phase diagram shown above is _ °C.

Accepted Answer

The answer of The normal boiling point of the substance...

Question 16

Of the following, is an exothermic process.
Melting subliming freezing boiling

Accepted Answer

Freezing is an exothermic process because it releases heat as a liquid turns into a solid.

Question 17

The heating curve shown was generated by measuring the heat flow and temperature for a solid as it was heated. The slope of the segment corresponds to the heat capacity of the solid.

Accepted Answer

The slope of segment AB corresponds to the heat capacity of the solid because this segment represents the phase where the substance is being heated as a solid, and its temperature is increasing without a phase change. The slope here indicates how much heat is required to raise the temperature of the solid, which is the definition of heat capacity.

Question 18

According to the phase diagram shown above, the normal boiling point of this substance is°C

Accepted Answer

The normal boiling point is the temperature where the vapor pressure of the liquid is equal to 1 atm. Looking at the phase diagram, we can see that the vapor pressure of the liquid reaches 1 atm at approximately 29°C, so the answer is B.

Question 19

The principal source of the difference in the normal boiling points of ICl (97°C; molecular mass 162 amu) and Br₂(59°C; molecular mass 160 amu) is both dipole- dipole interactions and London dispersion forces.

Accepted Answer

The answer of The principal source of the difference in...

Question 20

Of the following, has the highest boiling point.

Accepted Answer

Bromine (Br2) has the highest boiling point among the given options due to its larger molecular size and stronger London dispersion forces compared to the other diatomic molecules listed.

Quiz 11: Intermolecular Forces, Liquids, and Solids