ACS Physical Chemistry: Thermochemistry 2026 – 400 Free Practice Questions to Pass the Exam

An extensive property is characterized by its dependence on the amount or size of the system. This means that for extensive properties, if the quantity of material is doubled, the value of the property will also double. Examples of extensive properties include mass, volume, and total energy. These properties are inherently linked to the quantity of substance present in the system.

In contrast, intensive properties do not depend on the system size or amount of material. Instead, they remain constant regardless of the quantity of material present. Common examples of intensive properties are temperature, pressure, and density.

The correct choice emphasizes this critical distinction, as extensive properties are fundamentally based on how much of a substance is present, highlighting their direct relationship with system size. Recognizing this distinction is crucial for understanding how different physical properties behave under various conditions in thermochemistry.