By using electrolysis one can separate hydrogen and oxygen, but when burning hydrogen and oxygen together steam is released, therefore creating water. My question is:

how much of the original quantity of water would be lost after this process?


2 Answers 2


Theoretically, none.

Actually, since the gases are produced in a damp environment, there would be a lot of water vapor in the gases. You could easily remove most of the water vapor, but some (maybe as much as 1%) would still be in the gases.

I think it would be best to elaborate on what you mean as water being lost?

  • $\begingroup$ I agree with the theoretical answer that it's none, but we don't leave in a theoretical world. What I mean by lost is that there might be a delta of water, that is new quantity minus old quantity, because of the enviroment conditions. Giving that the enviroment is a closed container with hydrogen and oxygen produced from electrolysis and then fire is applied. Obviously natural water isn't pure, but let's take the other components out of the equation. So then what we're left with is the new quantity of water, which theoretically is equal to the old quantity, but practically? $\endgroup$ Commented Aug 9, 2014 at 19:10
  • $\begingroup$ In a closed container, you wouldn't lose any water. $\endgroup$
    – LDC3
    Commented Sep 9, 2014 at 0:51
  • $\begingroup$ So that being the case: A solar panel splitting water then recombining them using combustion would lose no water but produce heat... Just where does the loss - there must be one - occur? Is it that it takes loads of power to split it? $\endgroup$
    – vtg100
    Commented Jan 5, 2017 at 13:12
  • $\begingroup$ You haven't got something for nothing. You just stored some energy from the Sun in a novel way. $\endgroup$
    – badjohn
    Commented Nov 17, 2018 at 14:46

In the example of a system electrochemically (solar panel) splitting water into hydrogen and oxygen storing them, then burning the gasses, in an ideal system there would be no loss.

However, hydrogen is a very small molecule that can intercalate into materials, there by slowly diffusing outside of the system (and potentially embrittling them see: https://en.wikipedia.org/wiki/Hydrogen_embrittlement). Furthermore, any small defect in a seal on the hydrogen storage and delivery side of the system would cause a substantial loss of hydrogen.


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