I use a vacuum desiccator to remove dissolved gas in a NaOCl solution (2.5wt%)
The vacuum pressure is about 2 kPa and I observed the solution start to boiling.
However, dissolved gas is still eluted after the NaOCl solution is stored in vacuum for about 1 week.
In general, dissolved gas in water is sufficiently removed in about two days.
In my opinion, I couldn't completely remove the dissolved gas due to a chemical reaction that I am not familiar with.
Why can't I remove dissolved gas in an NaOCl solution?
you are either observing diatomic oxygen or diatomic chlorine evolution. These both have electrode potentials lower than the OCl- anion. You can observe the same thing in permanganate solutions.
George P Cobb Thank you for your kind answer... then, why are diatomic oxygen and diatomic chlorine generated? Are diatomic oxygen and diatomic chlorine, which have electrode potentials lower than OCl-, necessarily formed naturally?
and can I prevent the generation of diatomic oxygen and chlorine??
In solution, the compound is unstable and easily decomposes. At higher pH values (>8), chlorine is practically all in the form of hypochlorite anions. Try using diluted solutions for better stability.
Andrei Blasko Thank you, it's a really helpful answer.
But as far as I know the pH of 5wt% NaOCl solution is about 11.
Therefore, the 2.5wt% NaOCl solution that I am currently using is also considered to have a fairly high pH.
Does the diluted NaOCl solution have a higher pH and more stable?
The diluted NaOCl will have lower pH than the concentrated one. It is the [Na+] that dictates the pH.
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