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In the production of vinegar, where does the water come from?

I have heard that vinegar production involves these two reactions..

$$\ce{C2H6O {(ethanol)} + NAD+ -> C2H4O {(acetaldehyde)} + NADH + H+}$$

and

$$\ce{C2H4O {(acetaldehyde)} + NAD+ + H2O -> C2H4O2 {(acetic acid)} + NADH + H+}$$

But I don't see where water comes from as an input into the second reaction. Like if it's added manually or if it's produced by something else.

Note- there was an additional part of the question which i've since removed.. some of that is addressed https://biology.stackexchange.com/questions/56995/do-acetic-acid-bacteria-use-the-electron-transport-chain-when-converting-ethanol

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barlop
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    In biochemistry, you typically have plenty of water around. – Ivan Neretin Feb 27 '17 at 12:46
  • I think this is relevant http://www.bbc.co.uk/schools/gcsebitesize/science/triple_edexcel/organic_chemistry/organic_chemistry/revision/6/ ethanol + oxygen → ethanoic acid + water C2H5OH (l) + O2 (g) → CH3COOH (aq) + H2O (l) <--- (CH3COOH being ethanoic acid / acetic acid / C2H4O2 which is key to the production of vinegar) another related- http://chemistry.stackexchange.com/questions/33135/which-one-is-the-best-notation-for-sodium-acetate – barlop Feb 28 '17 at 03:24
  • @Jan i've removed the additional aspect. – barlop Mar 12 '17 at 20:55
  • @Jan please explain to me why as soon as I remove that part of the question that you complained about, the question is then closed for completely different reason to the one you complained about? And how was this question not "Questions relating to observed chemical phenomena"? – barlop Mar 15 '17 at 23:46
  • I have reopened. See here. – orthocresol Mar 16 '17 at 13:31
  • Vinegar is made in a fermentation process of grape juice (short version). Now take a wild guess where the water comes from... –  Feb 27 '17 at 12:48
  • ok thanks, i've edited my question accordingly – barlop Feb 27 '17 at 13:37
  • See the timeline. It was closed way before your edit. I voted to reopen as soon as I saw your edit but nobody followed me. Thankfully, @ortho stepped in to perform the task. Unfortunately, unless you’re a diamond moderator, it takes five votes to reopen (but the same goes for closing). Also, any custom message always defaults to the ‘off topic’ close reasen for technical reasons. – Jan Mar 17 '17 at 19:44
  • @Jan i'm distinguishing between it saying "on hold" and it saying "closed". The timeline might not use the phrase "on hold", and might just call both "closed" regardless. My edit was when the question was marked "on hold" and not yet marked "closed". See the chat link posted by orthocresol where I mentioned that re "on hold" and "closed" and he replied re that. – barlop Mar 17 '17 at 23:25
  • @barlop [on hold] and [closed] are two different names for practically the same state; after five days of being [on hold] the system automatically (no user input required) switches it to being [closed]. While a question is [on hold], an edit will automatically push it to a review queue for reopening. Read more in the help centre – Jan Mar 17 '17 at 23:30
  • @Jan yeah, otho mentioned much of that in the chat link. It's still not wrong to distinguish the two. – barlop Mar 17 '17 at 23:49

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Life on Earth evolved in aquaeous solutions. Cells are made up mostly of water; most cells are approximately $70~\%$ water. Water is thus ubiquitous in biochemical reactions. Only few enzymes go great lengths to explicitly exclude water from active sites to prevent undesired side reactions.

Concerning the production of vinegar, that usually starts from some kind of liquid mixture — e.g. wine — which has a high water content. The initially resulting alcoholic solution is also very aquaeous. As stated above, there is ample water.

Jan
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  • Thanks. . I understand there are these two reactions too http://www.bbc.co.uk/schools/gcsebitesize/science/triple_edexcel/organic_chemistry/organic_chemistry/revision/6/ ethanol + oxygen → ethanoic acid + water and ethanoic acid + ethanol <--> ethyl ethanoate + water Is the water produced by those reactions a lot less than the water in the wine? – barlop Mar 03 '17 at 11:58
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    @barlop Yes. That water is at best equimolar to ethanol/acetate. Alcoholic fermentation rarely produces more than $15~%\ \mathrm{v/v}$ and alcohol is less dense and has a higher molecular weight than water so less moles of alcohol give more volume than water. – Jan Mar 03 '17 at 20:44
  • and by alcoholic fermentation, you mean the reaction(s)/process(es) that takes alcohol as input and produces acetic acid? (as opposed to the one that takes sugar as input and produce alcohol) – barlop Mar 03 '17 at 21:45
  • @barlop I meant the process that takes sugar and produces alcohol – the process typically used to create the substrate of vinegar fermentation (the one that produces acetic acid). By the way, alcohol concentrations at which the reactions you mention would become significant with regard to water production are those concentrations that no known organism is capable of surviving in. – Jan Mar 03 '17 at 21:50
  • thanks, also.. I have read https://en.wikipedia.org/wiki/Acetic_acid_bacteria "Some genera, such as Acetobacter, can oxidize ethanol to carbon dioxide and water using Krebs cycle enzymes." I normally associate krebs cycle with respiration and the electron transport chain. Would I be correct in thinking that this oxidative fermentation reaction ethanol+O2->acetic acid + water, is not respiration, it does not use the electron transport chain? – barlop Mar 04 '17 at 03:46