Properties and the state of a system

The properties of a system are those quantities such as the pressure, volume, temperature, and its composition, which are in principle measurable and capable of assuming definite values. There are of course many properties other than those mentioned above the density and thermal conductivity are two examples. However, the pressure, volume, and temperature have special significance because they determine the values of all the other properties they are therefore known asstate properties because if their values are known then the system is in a definite State. 

We can compute similar delta-values for changes inP, V, nt (the number of moles of component /), and the other state properties we will meet later. 

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A lumped-parameter representation means that spatial variations are ignored, and the various properties and the state of a system can be considered homogeneous throughout the entire volume. A distributed-parameter representation, in contrast, takes into accoimt detailed variations in behavior from point to point throughout the system. All real systems are, of course, distributed in that there some variations occur throughout them. As the variations are often relatively small, they may be ignored, and the system may then be lumped. ... 

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