Answer to Question #120749 in Molecular Physics | Thermodynamics for Abhishek

Question

What are intensive and extensive thermodynamic variables ? Show by giving examples that (i) the ratio of two extensive variables is intensive, and (ii) the specific value corresponding to an extensive variable is an intensive property.

Answer 1

The thermodynamic property can be divided in two classes,

1. Intensive properties.
2. Extensive properties.

An intensive property is independent of the amount of mass. The variables which are independent of the size or amount of substance that is called intensive variables.

Example: Density is an intensive variable. (because it does not depend on the amount of that substance)

The variables which depend on the size/ amount of the substance is called extensive variables. It is additive for independent, non interacting subsystems

Example: Mass and volume are extensive variables. (Because they are directly measuring the amount of substance)

The ratio of object's mass and volume is the example of two two extensive properties.

while density is the intensive properties.