Problem 13 - Chemistry The Central Science In Si Units

Question

Which of the following statements is false? (a) Gases are far less dense than liquids. (b) Gases are far more compressible than liquids. (c) Because liquid water and liquid carbon tetrachloride do not mix, neither do their vapors. (d) The volume occupied by a gas is determined by the volume of its container.

Step-by-Step Solution

Answer

Statement (c) is false.

Step 1: Understand the General Properties of Gases

Gases have unique characteristics compared to liquids and solids. They have a much lower density, are highly compressible, and expand to fill their containers. These properties will help assess each statement.

Step 2: Analyze Statement (a)

Statement (a) is "Gases are far less dense than liquids." The density of a substance in the gaseous state is typically much lower than in the liquid state due to the larger amount of empty space between particles. Therefore, this statement is true.

Step 3: Analyze Statement (b)

Statement (b) is "Gases are far more compressible than liquids." Gases can be compressed significantly because there is a lot of space between particles, unlike in liquids. This makes this statement true.

Step 4: Analyze Statement (c)

Statement (c) is "Because liquid water and liquid carbon tetrachloride do not mix, neither do their vapors." The mixing behavior of vapors is not dependent on the mixing behavior of their liquids. Vapors can mix even if their corresponding liquids are immiscible. Therefore, this statement is false.

Step 5: Analyze Statement (d)

Statement (d) is "The volume occupied by a gas is determined by the volume of its container." Gases expand to fill their containers, meaning the gas will occupy the entire volume of the container. This means the statement is true.

Key Concepts

Density of Gases

Gases are known for having a much lower density compared to solids and liquids. This is because the molecules in a gas are spread out, leaving a lot of space between them. In terms of understanding how to compare the densities of different states of matter, here are a few key points to remember:

• Gas molecules are far apart, which means there is less mass in a given volume of gas compared to liquids or solids.
• This spacious arrangement allows gases to be lighter and easier to move around.
• The density of gases can be altered by changing conditions like pressure and temperature, but they will generally remain lighter than their liquid and solid counterparts.

This is why gases are often used in applications where lightweight materials are needed, whether it’s for balloons, airships, or insulation.

Compressibility of Gases

Compressibility is a measure of how much the volume of matter decreases under pressure. Gases are highly compressible owing to the vast distances between their particles. Here's what makes gases uniquely compressible:

• When pressure is applied, gas particles can be pushed closer together, significantly reducing the volume the gas occupies.
• This property is in stark contrast with liquids and solids, where particles are already closely packed and cannot be easily compressed.
• The high compressibility of gases makes them practical for use in cylinders for cooking gases, scuba tanks, and medical oxygen tanks, where they can be stored in compact volumes and expanded when needed.

Such characteristics of compressibility are crucial in applications where efficient storage and transportation of gases are required.

Gas Volume and Container

One of the fundamental properties of gases is that they will always take the shape and volume of their container. This means that the volume a gas occupies is directly related to the size of the container it is put into:

• Gases will spread out evenly until they fill the entire volume at a given pressure.
• If you increase the volume of the container, the gas will expand to fill it completely, remaining at the same pressure if temperature is constant, according to Charles's Law.
• This property is particularly important in understanding how gases behave in closed environments like balloons, sealed rooms, or industrial tanks.

Understanding how gas volume changes with container volume helps in designing systems where gas allocation and movement are critical, such as in HVAC systems or pneumatic tubes.