Q. 50

An ideal gas is allowed to expand against a constant pressure of 2 bar from 10 L to 50 L in one step. Calculate the amount of work done by the gas. If the same expansion were carried out reversibly, will the work done be higher or lower than the earlier case? (Given that 1 L bar = 100 J)

Answer :

o For the first case, this is an irreversible expansion of the ideal gas occurs, hence the amount of work done = -pext ∆V


= - 2 bar × (50 – 10 ) L = - 80 L bar.


Now, it is given that 1 L bar = 100 J


So , -80 L bar = (-80 × 100) = -8000 J = -8 KJ is the amount of work done in the above process.


o If the same expansion were carried out reversibly, (i.e. through infinite steps) then the internal pressure of the gas will be infinitesimally larger than the external pressure and this will be the case in every stage of expansion. Therefore, the work done will own a higher value than the earlier case.


Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Enthalpy & Heat Capacity | Interactive Quiz55 mins
Kinetic Theory of Gases46 mins
Interactive Quiz on Gas LawFREE Class
First law of thermodynamics64 mins
Enthalpy & Heat Capacity65 mins
Introduction to Thermodynamics63 mins
Interactive Quiz on first law of thermodynamics44 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses