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Reversible vs. Irreversible

Posted: Wed Feb 05, 2020 10:40 am
by Sydney Pell 2E
What makes an expansion reversible vs irreversible?

Re: Reversible vs. Irreversible

Posted: Wed Feb 05, 2020 1:25 pm
by LNgo 1G
An expansion is reversible when temperature is constant, but pressure and volume are variables; it is irreversible when pressure is constant and temperature changes.

Re: Reversible vs. Irreversible

Posted: Wed Feb 05, 2020 4:10 pm
by MaryBanh_2K
An expansion is reversible when the temperature is constant. This process is gradual and requires more work. It is reversible because everything is at equilibrium and therefore entropy is equal to zero. During a reversible expansion, work is negative and the system is losing energy by expanding; however, the lost energy is being replaced by the surrounding heat which is why q is positive. On the other hand, expansion is irreversible when pressure is constant. This process occurs spontaneously and suddenly, so it requires less work and entropy is greater than zero.

Re: Reversible vs. Irreversible

Posted: Thu Feb 06, 2020 10:17 pm
by 805312064
Reversible reactions are always at equilibrium (entropy = 0) because all energy lost from expansion is replaced by the surrounding heat! In contrast, irreversible reactions occur quickly - too quickly for the energy to be replaced.