Question

How does an intensive property differ from an extensive property?

Short answer

Intensive properties do not depend on system size, while extensive properties do.

Step-by-step solution

Understand the Concepts

Intensive and extensive properties are terms used in thermodynamics to describe physical properties of a system. It is important to recognize the difference between them based on how they depend on the size or extent of a system.

Define Intensive Properties

Intensive properties are those that do not depend on the amount of substance present. Examples include temperature, pressure, and density. These remain the same regardless of the size or mass of the system.

Define Extensive Properties

Extensive properties depend on the amount of substance in the system. Examples include mass, volume, and total energy. If the size of the system changes, so do these properties.

Apply Understanding

Consider a system where you double the amount of substance. Intensive properties will remain unchanged, while extensive properties will double due to the increase in quantity of the material.

Key concepts

Extensive Properties

Extensive properties are characteristics of a system that change when the size of the system changes. They depend directly on the amount of substance present. Therefore, extensive properties increase or decrease proportionally with the size of the system. For example, if you have a container filled with water and you double the amount of water, the total mass and volume—both extensive properties—will also double. This is a key distinction that helps identify such properties.

• Mass - Amount of material affects mass directly.
• Volume - More substance means more space occupied.
• Total Energy - Depends on the total matter present.

Recognizing extensive properties helps in calculations involving material balance and energy calculations in thermodynamics.

Thermodynamics

Thermodynamics is a branch of physics that focuses on the relationships between heat and other forms of energy. It deals with the principles governing the conversion of energy from one form to another and how it affects matter. Thermodynamics is based on very fundamental principles that apply universally:

• First Law - Energy cannot be created or destroyed.
• Second Law - Entropy of an isolated system always increases.
• Third Law - Entropy of a perfect crystal at absolute zero is zero.

This field plays a critical role in engineering, chemistry, and even biology as it explains the behavior of systems at different scales and what happens within systems whether they are large or small, enclosed or open.

Physical Properties

Physical properties are characteristics of a substance that can be observed or measured without changing the substance’s identity. They can be extensive or intensive. Physical properties tell us about the state and condition of a material, and they are crucial for identifying substances. Examples of physical properties include:

• Color - Visible property that does not affect mass or volume.
• Melting Point - Temperature at which a solid becomes a liquid.
• Boiling Point - Temperature at which a liquid becomes a gas.
• Density - An example of an intensive property, since it doesn't change with the amount.

Understanding physical properties is vital for laboratory applications and in determining the use of materials in processes like manufacturing and product testing.

System Size Dependency

System size dependency refers to how the properties of a system can alter with changes in the size or amount of material in the system. This is crucial in differentiating extensive properties from intensive properties.
Extending a system by adding more substance will inherently change the extensive properties because they are scale dependent. This concept is essential in scientific calculations and experiments where precision in measurement is crucial.

• In extensive properties, change in amount changes the property.
• In intensive properties, property remains the same regardless of system size.

Understanding system size dependency helps in maintaining consistency in observations and results in processes that involve change or scalability.