13
$\begingroup$

I learnt that Gibbs free energy is the maximum amount of non-expansion work. But the phrase non expansion work confuses me. Work is defined as pressure times change in volume. If there is no expansion, how can work be done?

$\endgroup$
2
  • $\begingroup$ It's when I stair-climb the Willis Tower in Chicago each November for the Shirley Ryan AbilityLab. I certainly don't expand during the climb, but I do work against Earth's gravity. $\endgroup$ Dec 19, 2022 at 13:13
  • $\begingroup$ You do have to push aside the air you encounter as you rise that takes extra energy. Try climbing up in a tank of water with negative buoyancy. This explanation of Gibbs free energy is very non general. $\endgroup$
    – jimchmst
    Dec 20, 2022 at 0:08

1 Answer 1

18
$\begingroup$

Pressure-Volume work is a type of mechanical work .
There are also non-mechanical forms of work where in pressure and volume terms are not involved .
The most famous example is electrical work . The work done to move electrical charges ( like motion of electrons in a conductor) comes under this category .

$\endgroup$
1
  • $\begingroup$ Another example is the stirring of a liquid in a tank $\endgroup$ Jul 25, 2015 at 1:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.