Isobaric and Isochoric Processes in Thermodynamics

In Physics and Chemistry (Thermodynamics), we study how gases behave when heat is added or removed. Two fundamental thermodynamic processes are the Isobaric and Isochoric processes. Let's understand them simply.

Question (Click to Flip)

What is an isobaric process?

Answer

An isobaric process is a thermodynamic process in which the pressure of the system remains constant while the volume and temperature change.

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Key Facts

Isobaric: Pressure (P) is constant (ΔP = 0). Work is done.

Isochoric: Volume (V) is constant (ΔV = 0). Zero work is done.

Memory Trick: Iso'baric' (Bar is a unit of pressure). Iso'choric' sounds like container (Volume).

1. Isobaric Process (Constant Pressure)

Meaning: The prefix 'Iso' means 'equal' or 'constant', and 'baric' relates to pressure. Therefore, an Isobaric process is a process where the pressure remains constant while the volume and temperature change.
Work Done: In an isobaric process, the gas expands or compresses, so work is done. The formula for work done is W = P × ΔV (Pressure multiplied by the change in volume).
Real-life Example: Boiling water in an open pan. The temperature and volume of the steam increase, but the pressure remains constant at 1 atmosphere (atmospheric pressure).

2. Isochoric Process (Constant Volume)

Meaning: 'Iso' means 'equal', and 'choric' relates to volume. Therefore, an Isochoric process (also known as an isometric process) is a process where the volume remains constant while the pressure and temperature change.
Work Done: Because the volume does not change (ΔV = 0), No work is done in an isochoric process (W = 0). All the heat added goes entirely into increasing the internal energy (temperature) of the gas.
Real-life Example: Heating a gas inside a rigid, sealed metal cylinder. The gas gets hotter and the pressure builds up, but the volume cannot expand because the container is rigid.

Questions and Answers

What is an isobaric process?+

An isobaric process is a thermodynamic process in which the pressure of the system remains constant while the volume and temperature change.

Why is the work done in an isochoric process zero?+

Work done by a gas is defined as Pressure x Change in Volume (W = PΔV). In an isochoric process, the volume is constant (ΔV = 0). Therefore, the work done is exactly zero.

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