weiming1998 - 27-1-2012 at 03:54
I have seen many sources suggesting to make MnSO4 by sulfuric+oxalic acid+MnO2. Why can't I just use H2SO4, or NaHSO4 by itself? What would happen?
Would H2O2 evolve? I know that because MnO2 is oxidizing, and you need a reducing agent to reduce the oxidation state of Mn. But what happens when I
just react it with an acid? Any help is appreciated.
I have googled and used the search button on Sciencemadness, and I can't find anything related about the issue at all except that there should be a
reducing agent.
ScienceSquirrel - 27-1-2012 at 04:15
If your sulphuric acid is strong and hot enough then the managanese dioxide will dissolve forming managanese sulphate, water and oxygen.
The reaction takes place under milder conditions in the presence of a reducing agent.
weiming1998 - 27-1-2012 at 04:22
Would there be a reaction at all if I used, say cold dilute H2SO4, or NaHSO4?
woelen - 27-1-2012 at 05:09
No, that combination will not react and your MnO2 simply remains suspended in the solution. You definately need a reductor to convert the MnO2 to
Mn(2+).
weiming1998 - 27-1-2012 at 05:21
I am actually trying to heat a water/battery paste(soluble compounds dissolved) mix with NaHSO4. Bubbles of oxygen gas seems to be liberated (fizzing
can be heard) and the impurities seems to float upwards in a sticky, black goo. I will try to cool off the mix later, filter, boil off water, and see
if any MnSO4/other compounds are produced.
weiming1998 - 27-1-2012 at 06:13
I have tried MnO2+NaHSO4:
Crude filtered battery paste is put in a beaker. A NaHSO4 solution is added. Fizzing instantly started, and the gas is a gas that will speed up
burning (oxygen). The solution is then heated. Bubbling became more vigorous and a thick, rubbery goo begin to float on the top of the solution. Some
water is added to the cooled down solution. It is filtered. Sodium carbonate is added. There is a lot of fizzing, but after the reaction, a white
precipate formed. I'm pretty sure that is MnCO3. But I didn't apply any reducing agent at all. Is hot NaHSO4 solution enough to reduce MnO2?
woelen - 27-1-2012 at 07:10
The battery stuff contains more than MnO2. Pure MnO2 does not react with NaHSO4 only, at least not in aqueous solution. Are you sure that the battery
stuff is not Mn2O3 or some hydrated version of that? Usually it also contains carbon and it also may contain some electrolyte in order to make it
conductive.
weiming1998 - 27-1-2012 at 07:30
Maybe some of the stuff is Mn2O3 because it is an old battery. I doubt about electrolytes though. The paste was carefully washed. Carbon and other
insoluble gunk is filtered off before sodium carbonate was added.