Good day guys,

I was reading some books on physical thermodynamics, they explain that for system undergoing a chemical reaction whose $\Delta G < 0$ indicating that the reaction can then provide us with a max non-PV work of $W_{max} = - \Delta G$

However, what happens when the reaction is not spontaneous, is $\Delta G$ the minimum work we need to supply? The books I have do not explicitly mention this statement, they only state it for work obtained from spontaneous reactions.

  • $\begingroup$ It's the amount of work you/surroundings must do to the system so that the (non-spontaneous) process goes forward. That is, $W=\Delta G$ $\endgroup$
    – joseph h
    Commented Nov 28, 2023 at 6:02
  • $\begingroup$ Is it the total amount of work we must supply or the minimum ? One of my book presents this equation as an inequality: $W \le \delta G $. $\endgroup$
    – RMS
    Commented Nov 28, 2023 at 6:22
  • $\begingroup$ the difference $\Delta G -W$ is the dissipated heat. $\endgroup$
    – hyportnex
    Commented Nov 28, 2023 at 14:51
  • $\begingroup$ here are two similar questions for the Helmholtz free energy $F$ with obvious changes to your question on $G$ physics.stackexchange.com/questions/761649/… and physics.stackexchange.com/questions/755441/… $\endgroup$
    – hyportnex
    Commented Nov 28, 2023 at 15:56
  • 1
    $\begingroup$ @RMS it’s the minimum. $\endgroup$
    – joseph h
    Commented Nov 28, 2023 at 22:07


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