The Free Energy ge and the Work a System Can Do Thermodynamics developed ater th

Question

The Free Energy ge and the Work a System Can Do Thermodynamics developed ater the invention of the steam engine, a maios that spawned a new generation of machines. Thus, some of the field's key or advance eas applied o; the relationships between the free energy change and the work a system can d AG is the uaximum useful work that can be done by a sys tem during a spontaneous process at constant T and P: AG Wmax (20.9) make a nonspontaneous ?G is the runmuun work that must be done to a system to process occur at constant T and P. the The free energy change is the maximum work the system can possibly work it actually does is always less and depends on how the free energy is released Let's consider the work done by two common system engine and a battery 1. "Useful" work done by a car engine. When gasoline (represented by octane, C,H) is burned in a car engine, CH1)O(g8CO,(8)+9H20(8) a large amount of energy is released as heat (AHy0), and because the number of moles of gas increases, the entropy of the system increases (Ay0). Therefore, the reaction is spontaneous (AGy0). The free energy released turns the wheels, moves the belts, plays the radto, and so on-all examples of "useful" work. However, the maximum work is done by any spontaneous process only that IS, in an nfinite number o steps. Of course, in any real process, performed in Ginity number of steps, that is, irreversibly, so the maximum work is never done. Any free energy not used for work is lost to the surroundings

Explanation / Answer

1)G is the maximum non expansion work under constant T and P

dU=dq+dwexpansion+dwnonexpansion(1st law of thermodynamics)

du<Tds-PdV+dw(ds>dq/T....clausius inequality,expansion work=-PdV)

dU+PdV-TdS<dw

dU+(PdV+VdP)-(TdS+SdT)<dW[we add VdP and SdT arbitrarily ,they are 0 since T and P are constant)

dU+d(PV)-d(TS)<dW(product rule)

d(U+PV-TS)<dW

dG<dW (since U+PV=G)

2)A reversible process is infiitely slow.Imagine that the forward reaction just barely faster than the reverse reaction.If a process does work on surroundings we get more work if it is done slowly because less heat is lost to the surroundings.energy released by a reversible process can do maximum amount of work because less energy is lost as heat.If a process is done quickly (irreversibly)tends to generate turbulance and fiction resulting in heat loss to the surroundings.

3)Work is required energy to move something against a force.energy of system change due to work or other for of energy like heat.work and heat is form of energy and they are iterconvertible

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