Question 1

The change of state from a liquid to a gas is called ________.

Accepted Answer

Evaporation is the change of state from a liquid to a gas without boiling occurring.

Question 2

Which of the three phases of matter (solid, liquid, or gas) features particles in a fixed, rigid arrangement?

Accepted Answer

The solid phase features particles in a fixed, rigid arrangement, meaning they are tightly packed and do not move around freely like in a liquid or gas.

Question 3

Between individual molecules of NO₂ in the solid state, which of the following types of intermolecular forces would you expect to be dominant?

Accepted Answer

NO₂ is a polar molecule, and in the solid state, the dominant intermolecular forces are dipole-dipole interactions due to the permanent dipole moment of the molecules.

Question 4

The change of state from a solid to a gas is called ________.

Accepted Answer

Sublimation is the change of state from a solid directly to a gas without passing through a liquid state.

Question 5

Which of the three phases of matter (solid, liquid, or gas) has particles moving at the highest average velocity?

Accepted Answer

In a gas, the particles have the highest average velocity because they have the most kinetic energy and are able to move freely throughout the container in which they are held. In solids, the particles are tightly packed and their movement is limited, while in liquids, the particles have more freedom of movement than solids but are still relatively close together.

Question 6

Which of the following substances would you expect to be a liquid at room temperature, assuming that strong intermolecular forces need to be present to be a liquid at room temperature?

Accepted Answer

CS2 has strong intermolecular forces due to its linear shape, which allows for strong dipole-dipole interactions and London dispersion forces between molecules. N₂, H₂, and O₂ are all diatomic molecules with minimal intermolecular forces, so they exist as gases at room temperature.

Question 7

Which of the three phases of matter (solid, liquid, or gas) has particles that are fast-moving and independent of each other?

Accepted Answer

Gas particles are fast-moving and independent of each other.

Question 8

Which of the following is not a solid at 0 °C?

Accepted Answer

At 0°C, salt (NaCl) is a solid, sugar (C12H22O11) is a solid, and iron (Fe) is a solid. Carbon dioxide (CO2) is a gas at 0°C and standard pressure.

Question 9

The change of state from a solid to a liquid is called ________.

Accepted Answer

The change of state from a solid to a liquid is called melting.

Question 10

Which of the following sublimes?

Accepted Answer

Mothballs are made of naphthalene or paradichlorobenzene which are substances that can sublime, meaning they can transition from a solid to a gas without passing through a liquid state. Sugar, iron, and margarine do not sublime.

Question 11

Which of the three phases of matter (solid, liquid, or gas) features particles that are no longer held together by intermolecular forces?

Accepted Answer

In the gas phase, particles have enough kinetic energy to overcome intermolecular forces and are no longer held together by them. In the solid and liquid phases, particles are still held together by intermolecular forces, but the strength and arrangement of these forces are different in each phase.

Question 12

A change of state from a gas to a liquid is called ________.

Accepted Answer

A change of state from a gas to a liquid is called condensation. Sublimation involves a change from a solid directly to a gas, evaporation involves a change from a liquid to a gas, and melting involves a change from a solid to a liquid.

Question 13

Which of the following statements is true about intermolecular forces of attraction between molecules?

Accepted Answer

A) Intermolecular forces of attraction between molecules tend to hold molecules together.
B) Cooling is often responsible for the substance's liquefaction due to a decrease in kinetic energy, allowing the molecules to come closer together.
C) The solidification of a substance usually requires lower temperatures than in the case of liquefaction because the intermolecular forces become stronger as the temperature decreases, causing the molecules to come closer together and form a solid.

Question 14

Which of the following chemical substances would you expect to have the highest melting point?

Accepted Answer

Water, H₂O, has the highest melting point among the options due to its ability to form hydrogen bonds, which are stronger intermolecular forces compared to the other substances listed. This results in a higher amount of energy required to break these bonds and change the state from solid to liquid.

Question 15

The term "normal" boiling point indicates ________.

Accepted Answer

The term "normal" boiling point specifically refers to the temperature at which a liquid boils under the atmospheric pressure found at sea level. Option A is referring to the normal evaporation point, which is not the same as the normal boiling point. Option C is incorrect because the boiling point can vary depending on the pressure conditions.

Question 16

Which of the following chemical substances would you expect to have the lowest boiling point (you may consider molecular mass and the degree of intermolecular forces as primary controlling factors)?

Accepted Answer

CH₄ has the lowest molecular mass and only exhibits London dispersion forces, which are the weakest intermolecular forces, leading to a low boiling point. The other choices have higher molecular masses and more complex structures, allowing for stronger intermolecular forces (dipole-dipole interactions and hydrogen bonding), leading to higher boiling points.

Question 17

Which of the three phases of matter (solid, liquid, or gas) features particles that are easily compressible?

Accepted Answer

Gas features particles that are far apart and have weak intermolecular forces, making them easily compressible. In contrast, solids and liquids have particles that are closer together and have stronger intermolecular forces, making them much less compressible.

Question 18

Which of the three phases of matter (solid, liquid, or gas) has particles separated by the least amount of distance?

Accepted Answer

Solids have particles that are tightly packed together, so they are separated by the least amount of distance compared to liquids and gases. In liquids, particles are more spread out than in solids, and in gases, particles are even more spread out.

Question 19

Which of the following does not sublime?

Accepted Answer

Salt does not sublime. Sublimation is the process by which a solid turns directly into a gas without passing through the liquid phase. Mothballs, iodine crystals, and dry ice all sublime.

Question 20

Which of the following statements about London forces is correct?

Accepted Answer

All of the statements are true. London forces are also called dispersion forces and are relatively weakly attractive. They can occur between polar and nonpolar molecules.

Quiz 7: Intermolecular Forces and the Phases of Matter