I dissolved some thiosulfate and found that the solution is acidic and I added hydrogen peroxide to it and the solution turned basic.
This should be the other way around right.
For me the universal indicator turned from red to greenish blue on adding hydrogen peroxide.
Any explanation to why that occured?
[edit by mod]
Clarified the title.
[Edited on 4-12-2019 by j_sum1]hodges - 1-12-2019 at 19:06
I tested some medical (3%) hydrogen peroxide from the drug store and it is acidic - pH around 5. This is likely due to additives that help prevent
decomposition.
Intuitively, I would expect sodium thiosulfate to be slightly basic, since its constituents are a strong base and a (presumably) weaker acid.
However, when I tried adding a couple sodium thiosulfate crystals to water, the pH went up only very slightly, probably within the margin of error of
the reading. So it is probably very close to neutral. I don't see any reason to expect it would be acidic.
Not sure why you are seeing the opposite, although with such weakly acidic and basic solutions its possible that even a small amount of impurity would
have a rather large effect on the pH.
vibbzlab - 2-12-2019 at 06:37
I used the medical peroxide 3% one. So that's it. Thanks UC235 - 2-12-2019 at 15:49
The dyes in most pH indicators are sensitive to redox and can turn unpredictable colors in the presence of reducing agents (thiosulfate) or oxidizing
agents (hydrogen peroxide).fusso - 2-12-2019 at 20:33
Title too vague and clickbaity. It should mention what you're actually doing. Change to a clearer one.
[Edited on 191203 by fusso]Tsjerk - 2-12-2019 at 21:38
pka H2O2 = 11,7 arkoma - 3-12-2019 at 16:44
Aga started a thread on this same topic ages ago. Could we get a merge Mod's?j_sum1 - 3-12-2019 at 19:05
