Question

Compared to either a liquid or a solid, a typical gas has (A) a higher density and contains molecules that are closer together. (B) a higher density and contains molecules that are father apart. (C) a lower density and contains molecules that are father apart. (D) a lower density and contains molecules that are closer together.

Short answer

A typical gas has a lower density and contains molecules that are farther apart compared to a liquid or a solid. The correct answer is (C) a lower density and contains molecules that are farther apart.

Step-by-step solution

Understanding states of matter

In the solid state, the particles (atoms, ions, or molecules) are closely packed together in a rigid arrangement. In contrast, the particles in liquids are less closely packed and can flow around each other. Finally, the particles in gases are widely spaced and move randomly with high speeds.

Comparing densities

Density is defined as mass per unit volume. The more closely packed particles are, the higher the density. Due to the tightly packed particles in solids, they have the highest density, while liquids have a lower density because of their loosely packed particles. Gases have the lowest density, as their particles are widely spaced.

Comparing particle distances

The relative distance between particles depends on how closely they are packed. In the solid state, particles are the closest, followed by the liquid state. In the gas state, particles have the highest average distance between them because they are widely spaced.

Answering the question

Based on our analysis, a typical gas has a lower density and its molecules are farther apart compared to a liquid or a solid. So, the correct answer is: (C) a lower density and contains molecules that are farther apart.

Key concepts

Density in Solids, Liquids, and Gases

Density is a measure that describes how much mass is contained in a given volume of a substance. It's calculated using the formula \( \text{Density} = \frac{\text{Mass}}{\text{Volume}} \). The arrangement and closeness of particles in a substance largely determine its density.

In solids, particles are tightly packed together in a fixed, orderly pattern. This results in a high density because a lot of mass is concentrated in a small volume.

• Solids: High density due to tight packing of particles.

Liquids have particles that are close but not as tightly packed as in solids. They can move past each other, which allows liquids to flow.

• Liquids: Moderate density with particles less rigidly packed.

Gases have particles that are widely spaced, resulting in the lowest density among the states of matter.

• Gases: Low density due to large distances between particles.

Particle Arrangement in Gases

In gases, particles are much more spread out compared to solids and liquids. The particles move in random directions at high speeds and are not bound in place like in solids.

This random and rapid movement means that there is a considerable amount of empty space between gas particles.

• Large Distances: Particles are far apart.
• High Mobility: Particles move quickly and freely.

Because gas particles are so far apart, they can easily be compressed or expanded, making gases highly adaptable in shape and volume when they change conditions of pressure and temperature.

Density Comparison Between States of Matter

When comparing the density of solids, liquids, and gases, it's clear that particle arrangement plays a crucial role.

• Solids: Densest because particles are close together and vibrate in place.
• Liquids: Less dense than solids; particles are close but move past each other.
• Gases: Least dense; particles are widespread and fast moving.

The pattern between these states is straightforward— the more closely packed the particles, the higher the density. Thus, solids typically have higher densities than liquids, and gases have the lowest densities. This understanding helps explain why a gas has a lower density and particles that are farther apart compared to other states of matter.