Property Diagrams of Pure Substances

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PROPERTY DIAGRAMS OF
PURE SUBSTANCES
SUBJECT : ENGINEERING THERMODYNAMICS

CONTENTS:
* Phase and pure substance
* Properties of a substance
* P-V diagram for a pure substance
* P-T diagram for a pure substance
* P-V-T surface
* T-S diagram for a pure substance
* h-s diagram for a pure substance

Thermodynamic Properties
* Characteristics by which physical properties of system may be described. e.g. pressure, volume, temperature, entropy, enthalpy etc. * Properties are the coordinates by which state of the system is described. * Any operation in which one or more properties of system may change is called change of state. * Thermodynamic properties are of two types :

Extensive properties- that depend on mass of the system.
Intensive properties – that are independent of mass of the system. Phase and pure substance
* The term phase refers to a quantity of matter that is homogeneous throughout in both chemical composition and physical structure. * Examples: Air, liquid+water vapor, oxygen+nitrogen gas mixture, alcohol+water mixture, oil+water mixture * Two phases can coexist during phase change.

* Pure substance is one that is uniform and invariable in chemical composition. A pure substance can exist in more than one phase but its chemical composition must be the same in each phase. * Examples: liquid water+vapor water at a fixed composition, A uniform mixture of gases, Air at cryogenic temperature, Air at room temperature

Diagrams or graphs:
* When any of the thermodynamic property is plot against another thermodynamic property , keeping third thermodynamic property constant during the analysis process a diagram is obtained. * This diagram is used to study about the phase change process for a substance. * This diagrams also give information about work done, quality of steam (in case of water), isotherm, critical point etc.

P-V diagram

* A PV diagram...
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