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Name: Olivia J.
Status: student
Age: 13
Location: N/A
Country: N/A
Date: 1/23/2004


Question:
I am doing an experiment on vitamin C and oxidation. I have an experiment set up, and i know oxidation is due to the reaction between oxygen and vitamin C, and that the vitamin looses hydrogen molecules. I am wondering though, what exactly happens between the oxygen and vitamin C to cause loss of hydrogen molecules, and why does putting your orange juice in the fridge slow down oxidation? The second question is easier to answer. The rule of thumb chemists use in the absence of any other data is that the rate of a chemical reaction approximately doubles for every 10 C. increase in temperature. So cooling orange juice from 25 C. to say 0 C. would decrease reactions by about 2.5 times.


Replies:
Your first question: How does ascorbic acid (vitamin C) work is much more complicated, and a quick Google search only made that more evident. There does not seem to be any simple chemical reaction(s) for the quenching of free radical chain reactions by vitamin C or other anti-oxidants for that matter. One can write down some "paper" chemical reactions, but seldom is the body's biochemistry so simple. I think it is safe to say that the exact mechanism is not known.

Vince Calder



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