Open Systems

[tinman]

What about the energy used to compress the  gas? Potential energy stored in the gas can only come from the battery. Surely the electrolysis stops as the pressure rises, as the Nernst equation demands more voltage due to a higher partial pressure of the gasses?  Yes some of the energy goes into heat, the rest into potential energy (pressure) of the gas?

The gas is the stored potential energy,not the pressure at which it is stored. The mass of gas(moles) produced dose not change regardless of pressure,only the volume changes with pressure.When you use your compressor to compress air,the extra load(higher power consumption) on the motor as the pressure builds in the tank is converted into what?-->yes,heat. As we want only compressed air,the heat is seen as waste heat. To raise the pressure of the compressed air,we produce more heat. As this system is designed to produce heat,then the heat energy is not seen as a waste.

So the energy didnt go into pressurising the gas,it went into producing the gas and heat. The heat is the disipated energy that is the pressure.

[MarkE]

Here is the problem you have with the !ideal gas law!-HHO is not an ideal gas.

To the extent that any gas deviates from the ideal gas law it always does so in a lossy way.

Second thing to remember is that regardless of volume and pressure,the mass !n!(the number of moles) of gas is constant. So regardless of pressure or volume the mass(moles of gas)remain the same. 241.8KJ of energy is produced for every mole of H2 burned.

Sure, but the number of moles of H₂ that get evolved from the water to later burn for each Joule of battery energy applied shrinks as the vessel pressure increases.

I repeat--> the mass (moles of gas)remain a constant regardless of pressure or volume

In that you are plain wrong.

1 mole of H2 will produce 241.8KJ of energy when burned.

Yes, but your assumptiona as to the number of moles evolved is incorrect.

Moving the piston with the gas pressure dose not change the mass of the gas-->dose not change the mole amount of gas,and dose not change the stored energy within that fixed mass of gas.

As has been explained to you multiple times now:  If the volume expands without doing any external work then the PV product remains fixed.  If external work is done, that work is transferred from the gas to the outside world and is forever lost.  If you stipulate a constant temperature: then the PV product falls.

PV is not gas mass(moles of gas) amount.

n remains constant.  n = PV/(rT).

So as i said,the stored energy within the gas dose NOT change because of a change in PV.

It changes and PV changes when you perform external work with the gas.

The PV can change without effecting the stored energy within the gas

That is at least hypotehtically true.

-->the given P can perform work upon the piston without effecting the mass(mole)amount of the gas.

That is also true.

As the moles of gas has remained the same,then the energy contained within that gas is unchanged when subject to a pressure drop.

That last bit is fundamentally wrong.

[MarkE]

The gas is the stored potential energy,not the pressure at which it is stored.

Wrong.  The product of the number of molecules and their temperature determines the energy which is equal to the pressure * volume product scaled by Boltzmann's constant.

The mass of gas(moles) produced dose not change regardless of pressure,only the volume changes with pressure.When you use your compressor to compress air,the extra load(higher power consumption) on the motor as the pressure builds in the tank is converted into what?-->yes,heat. As we want only compressed air,the heat is seen as waste heat. To raise the pressure of the compressed air,we produce more heat. As this system is designed to produce heat,then the heat energy is not seen as a waste.

What you keep missing is that any external work performed by expanding the gas reduces the PV product.  IE the gas temperature falls.  Now your energy which is proportional to n*T has fallen.  It's gone, over, done.

So the energy didnt go into pressurising the gas,it went into producing the gas and heat. The heat is the disipated energy that is the pressure.

That last bit is a tangled mess.

[profitis]

Quote frm pomodoro:  'I might be blind but how does the environment give
energy to this system?'

Unquote

Where does the heat flow come from in the following conversion liquid>gas.tinman breaks the bonds.environment works for phase change.environment adds work to this system which was not from tinman

[profitis]

Another analogy : tinman breaks bonds for zinc bromide solution.zinc forms.bromine liquid forms.environment does jakshit contributi.jakshit phase change