Thermodynamic State Variables And Equation Of State - Practice Questions & MCQ

Thermodynamic variables : Any thermodynamic system can be described by specifying some of the variables i.e; its pressure(P), volume(V), temperature(T), internal energy(U) and the number of moles(n). These parameters are called thermodynamic variables.

Extensive and Intensive properties/variables - 

• Intensive properties do not depend on the amount of matter that is present. These are bulk properties. Examples of intensive properties are - Density, Temperature ets.
• Extensive properties are those properties which depend on the amount of matter that is present. Examples of extensive properties are - Volume, Weight etc. 

Equation of state - The relation between the thermodynamic variables (P, V, T) of the system is called equation of state.

For n moles of an ideal gas, equation of state is PV = nRT

For n moles of a real gas equation of state is  $\left(P+\frac{a n^2}{V^2}\right)(V-n b)=n R T$

Thermodynamic process : The process of change of state of a system involves change of thermodynamic variables such as pressure P, volume V and temperature T of the system. The process is known as thermodynamic process.

Some important processes are -

(i) Isothermal process (ii) Adiabatic process (iii) Isobaric process (iv) Isochoric process

(v) Cyclic and non-cyclic process (vi) Reversible and irreversible process

Later, we will study all these process one by one in detail.

State and path function - 

State or Point function does not depend on the path followed by the thermodynamic process but it depends on the final and initial position of the process.

Path function depends on the path followed by a thermodynamic process and not on the initial and final states of the system. Example of point function is Internal energy and example of path function is Heat and work.