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Volume

The space occupied by the system.
An important extensive property of a system.
Units: SI = m3, AE = ft3

Density

Specific Volume

The volume of the system per mole of molecules within the system. (Intensive)

The volume of the system per unit of mass within the system. (Intensive)

The mass per unit volume of the system.

Molar Volume

Related Properties:

Volume

Pressure, volume, and temperature are the three most important properties in classical thermodynamics because they are the easiest properties to measure.

Lesson 1E: page 1 of 16

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Ch1, Lesson E, Page 1 - Volume

Pressure, volume and temperature. You are going to hear and see a lot about them in Thermo-CD.
The reasons are simple. P, V and T are important properties and they are relatively easy to measure.
Let’s start with the easiest property to understand: volume.
Volume is just the region of space occupied by the system.
Typical units are L, cubic meters and cubic feet.
That is simple enough, but we also need to define a few properties that are related to volume.
Molar volume, or V-wiggle is the ratio of the total volume of the system to the total number of moles of molecules in the system.
Because molar volume is the ratio of two extensive variables, it is an intensive variable.
Specific volume, or V-hat, is the ratio of the total volume of the system to the total mass of the system.
Specific volume is also an intensive property.
Finally, density is the ratio of the mass of the system to the volume of the system.
Density is the inverse of the specific volume and density is also an intensive property.
That wasn’t too bad, now lets press on to pressure.

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