Pure Substance and Two property Rule

Objectives of this video To understand Pure Substance Examples of Pure Substance To understand Two Property Rule

Pure Substance “A pure substance is defined as one that is homogeneous and invariable in chemical composition throughout its mass”

Examples of Pure Substance Atmospheric air Steam-water mixture Combustion products of a fuel

Two property rule According to two property rule, to determine thermodynamic state of any pure substance we need only two thermodynamic states, third state can be calculated with the help of various available formulae.

One such formula is ideal gas equation P. V = n. R One such formula is ideal gas equation P*V = n*R*T Where P: Pressure V: Volume n: Number of moles R: Universal gas constant T: Temperature

In the ideal gas equation formula we can easily observe that if we know the value of any two state variables from P, V and T. We can easily derive the value of third state variable.

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