1. Pure Substance and Two property Rule

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

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

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

5. 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.

6. 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

7. 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.

8. Thank You