Irreversible Expansion

Moderators: Chem_Mod, Chem_Admin

Tai Metzger 3K
Posts: 103
Joined: Sat Aug 24, 2019 12:17 am

Irreversible Expansion

Postby Tai Metzger 3K » Tue Feb 11, 2020 9:52 pm

What is irreversible expansion?

Hiba Alnajjar_2C
Posts: 108
Joined: Fri Aug 09, 2019 12:17 am

Re: Irreversible Expansion

Postby Hiba Alnajjar_2C » Tue Feb 11, 2020 11:25 pm

Irreversible expansion refers to work done against a constant external pressure. To calculate the work, you would use the equation w = -P(delta V). In an irreversible expansion, there is a big difference in internal and external pressure, which is why the expansion is much quicker than a reversible expansion. Also, the amount of work done in an irreversible expansion is less than that calculated for a reversible expansion.

Bryan Chen 1H
Posts: 58
Joined: Mon Jun 17, 2019 7:24 am

Re: Irreversible Expansion

Postby Bryan Chen 1H » Wed Feb 12, 2020 3:09 am

irreversible expansion refers to a gas expanding against a constant external pressure. use the equation w= -Pex(deltaV)

Miriam Villarreal 1J
Posts: 105
Joined: Sat Aug 17, 2019 12:16 am

Re: Irreversible Expansion

Postby Miriam Villarreal 1J » Wed Feb 12, 2020 9:00 pm

I’m addition free expansion of a gas is an irreversible process because the temperature of a gas undergoing a free expansion is not a meaningful quantity.
Also. When talking about an isothermal free expansion of a gas, we mean that the final temperature is the same as the initial temperature.

Tiffany_Chen 2K
Posts: 106
Joined: Fri Aug 30, 2019 12:15 am

Re: Irreversible Expansion

Postby Tiffany_Chen 2K » Wed Feb 12, 2020 9:59 pm

In the opposite way of thinking, reversible expansions are where there is an infinitesimal amount of changes to the system, thus allowing the system to be reversible. Irreversible expansions are typically a huge, sudden change that will take an equally large amount of energy to reverse (which is mostly reactions in life).

Kylie Lim 4G
Posts: 110
Joined: Sat Aug 17, 2019 12:15 am

Re: Irreversible Expansion

Postby Kylie Lim 4G » Wed Feb 12, 2020 10:46 pm

The example that was used in class was that in a reversible expansion, pressure is gradually decreased in amounts that are so small it remains in equilibrium with the surroundings. In an irreversible expansion the pressure is decreased suddenly and in large amount so that it can't be reversed.

Jialun Chen 4F
Posts: 108
Joined: Sat Sep 07, 2019 12:16 am

Re: Irreversible Expansion

Postby Jialun Chen 4F » Wed Feb 12, 2020 11:37 pm

Irreversible expansion keeps the pressure constant. It is relatively faster than reversible expansion, yet less efficient because it does less work.

Alison Trinh 1E
Posts: 104
Joined: Thu Jul 25, 2019 12:16 am

Re: Irreversible Expansion

Postby Alison Trinh 1E » Sun Feb 16, 2020 9:05 pm

A visual my TA provided regarding irreversible expansion would be if you had a piston with some external pressure acting on it and also some weight in the form of sand holding down on the piston. Irreversible expansion would be taking out the sand grain by grain until there is no more sand and thus no more weight holding the piston down.

Return to “Concepts & Calculations Using Second Law of Thermodynamics”

Who is online

Users browsing this forum: No registered users and 2 guests