I just started learning chemical thermodynamics and have come upon the definitions for extensive and intensive properties. I had a great deal of confusion over the exact meaning of intensive properties, but I believe I have come to a proper understanding of it after doing some extra reading. I will present my understanding below, and I just need to clarify that this is exactly what intensive properties are.

Intensive properties are defined differently for homogeneous and heterogeneous systems. For homogeneous systems, intensive properties are those properties that possess the same value at different points within the system and for the system as a whole. For heterogeneous systems, it no longer has anything to do with the value of the property for the system as a whole, but instead transforms into a local property, concerning only small volume elements within the system.

Is this correct, or is there some brushing up needed? As of now I am only concerned with the most general understanding of intensive properties. Hope you could shed some light on this. Thank you.

  • $\begingroup$ I think of intensive properties as not depending on the amount of material that is present, and consistent with your characterization for a heterogeneous system, except applying to both homogeneous and heterogeneous systems. Examples are temperature, pressure, specific volume, specific internal energy, specific entropy, etc. $\endgroup$ – Chet Miller Oct 22 '15 at 20:26
  • $\begingroup$ I would not say that "intensive properties" are defined differently for single-phase and multi-phase materials; rather, I would say that an intensive property is, per definition, a physical property of a single phase that does not depend on the amount of that phase. If your material is multi-phase, then at the phase boundaries the intensive properties suddenly change. $\endgroup$ – Yoda Oct 22 '15 at 20:32
  • $\begingroup$ @Anders MB You said what I was trying to say so much better than I did. But I will add that temperature and pressure don't typically change at phase boundaries, except for a curved boundary at which surface tension is important. There, the pressure does experience a discontinuity. $\endgroup$ – Chet Miller Oct 22 '15 at 23:26

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