[bg726]

When powder ascorbic acid is added to regular water, at what rate will the ascorbic acid degrade over hours or days?

[Sam (NG)]

"degrade" how exactly?  I'll have a search on Web of Science for you, i have no idea personally, but i would have thought that it took quite some time.

[bg726]

"degrade" how exactly?

Oxidize.

[Sam (NG)]

I can't find any resources for the oxidation in pure water, sorry, only the oxidation under the influence of specific catalysts.

Sorry i couldn't be more helpful.

[Borek]

I suppose he means oxidation with air oxygen.

[Yggdrasil]

I used to use 10% ascorbic acid in water for some biochemical assays and as a general rule, I would store the ascorbic acid solution in the dark at 4^oC for no more than 3 days.  So, the degradation happens on the scale of days (at least at 4^oC).

[ARGOS++]

Dear bg726, Dear Other,

Is it not a little toooo easy?
GOOGLE knows something about 846’000 references,   
a Lot of it in aqua different degree if You, or others try
to ask: “stability Ascorbic Acid ” !!!

One Example:     NO, NOT in water (Why?)

     http://www.annieappleseedproject.org/stabofasacin.html 
    “RESULTS: The orange juices from frozen concentrates
     contained 86 mg reduced vitamin C per fluid cup at initial preparation
     and 39 to 46 mg/c after 4 weeks of storage.

     Ready-to-drink juices averaged significantly lower reduced
     vitamin C: 27 to 65 mg/c at opening and 0 to 25 mg/c at expiration 4 weeks
     later. Ready-to-drink orange juices had twofold to threefold higher
     concentrations of oxidized vitamin C vs the orange juices reconstituted from
     frozen, and the decomposition rate of reduced vitamin C was similar for all
     juices, about 2% per day once opened. ”

Have fun!
Good Luck!
                    ARGOS⁺⁺