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Reversible vs Irreversible

Posted: Sun Feb 10, 2019 2:57 pm
by Nicole Garrido 2I
What makes a reaction or movement irreversible in a system and what makes it reversible? Why are the pressures different?

Re: Reversible vs Irreversible

Posted: Sun Feb 10, 2019 3:31 pm
by Anita Wong 1H
In a irreversible reaction, the reactants react to form the products, which cannot revert back into reactants. In reversible reactions, as the reactants react with other reactants to form products, the products are reacting with other products to form reactants. Combustion cannot be undone. i am not sure as to why the pressures are different

Re: Reversible vs Irreversible

Posted: Sun Feb 10, 2019 5:00 pm
by caseygilles 1E
I think the difference between reversible and irreversible work is that infinitesimally small changes in pressure are considered insignificant in irreversible systems and pressure is considered constant; whereas, in reversible processes, external pressure is not constant and infinitesimal changes will affect the system, which is why we use the integral to calculate work in reversible systems.

Re: Reversible vs Irreversible

Posted: Sun Feb 10, 2019 5:51 pm
by Ruiting Jia 4D
How come infinitesimally small changes affect reversible systems?

Re: Reversible vs Irreversible

Posted: Sun Feb 10, 2019 6:25 pm
by Tinisha 1G
Irreversible systems have a constant pressure. Reversible systems have a changing external pressure, and we use the integral to add up all the infinitely small work increments from each change in pressure

Re: Reversible vs Irreversible

Posted: Sun Feb 10, 2019 6:25 pm
by Tinisha 1G
Irreversible systems have a constant pressure. Reversible systems have a changing external pressure, and we use the integral to add up all the infinitely small work increments from each change in pressure

Re: Reversible vs Irreversible

Posted: Sun Feb 10, 2019 6:44 pm
by Kathryn 1F
So which one does more work? I think it would be reversible bc of the curve, but I'm not entirely sure why

Re: Reversible vs Irreversible

Posted: Sun Feb 10, 2019 7:54 pm
by KHuang1L
The question will tell you whether it is a reversible or irreversible reaction. The work done will be different because they use different equations to calculate work. Reversible reaction: W=-PV. Irreversible reaction: W=-nrTln(V2/V1).

Re: Reversible vs Irreversible

Posted: Sun Feb 10, 2019 8:26 pm
by Timothy_Yueh_4L
Kathryn 1F wrote:So which one does more work? I think it would be reversible bc of the curve, but I'm not entirely sure why

Reversible isothermal expansion would do more work because it calculates the amount of work done over the courses of the entire expansion, summing the work done at infinitesimally small intervals.

Re: Reversible vs Irreversible

Posted: Sun Feb 10, 2019 8:48 pm
by Kathryn 1F
Can an isothermal reaction be irreversible? Or is that only for reversible reactions?