Why Does Ascorbic Acid Concentration Change Over Time?

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Ascorbic acid concentration changes over time due to decomposition and oxidation processes. In solid form, such as a pill, the concentration remains stable over long periods, while in a solution, concentration increases as water evaporates. In fruit juices, oxidation leads to a decrease in ascorbic acid levels over time. The degradation results in a mix of undecomposed ascorbic acid and its decomposition products. Overall, both environmental conditions and the physical state of ascorbic acid influence its concentration changes.
Amili
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Why does ascorbic acid change in concentration over time?
 
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Can you give a little more detail? Under what conditions? How much time? Where did you hear this?
 
yup need more detail. If you are talking about a pill (though why you would be taking asorbic acid I don't know) the answer would be not much over long periods. In a solution (dissolved in water) it would get more concentrated as the water evaporates. Otherwise need more detail..
 
I'd surmise that this relates to ascorbic acid decomposing with time. The bottle of reagent powder then contains a mix of undecomposed ascorbic acid plus the solid products of decomposition. So you could say the grams of acid per teaspoonful of the powder falls with time.

In fruit juice, the ascorbic acid content oxidises, so this mechanism likewise decreases the ascorbic acid concentration with time.
 
Thread 'Confusion regarding a chemical kinetics problem'

Thread 'Confusion regarding a chemical kinetics problem'

TL;DR Summary: cannot find out error in solution proposed. [![question with rate laws][1]][1] Now the rate law for the reaction (i.e reaction rate) can be written as: $$ R= k[N_2O_5] $$ my main question is, WHAT is this reaction equal to? what I mean here is, whether $$k[N_2O_5]= -d[N_2O_5]/dt$$ or is it $$k[N_2O_5]= -1/2 \frac{d}{dt} [N_2O_5] $$ ? The latter seems to be more apt, as the reaction rate must be -1/2 (disappearance rate of N2O5), which adheres to the stoichiometry of the...
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