Australia's Science Forum

Hi All,

Does anyone know whether we can use manganese dioxide for oxygen pracs at all? I thought it is recently classified as a dangerous chemical, I could be wrong..... anyone to clarify this please

Thanks in advance

It's been addressed somewhere else here, but basically it goes like this:

MnO2 on its own is considered a "naughty" these days. However, it is possible to make cute little MnO2 pellets by mixing 1 teaspoon of MnO2 and 1 teaspoon of Plaster of Paris in a little 100ml takeaway container, with enough water to make a paste. Then, using a popstick, drop little blips of the mixture onto a sheet of cling wrap, so that they look a bit like choc bits, only not as yummy. Don't get lazy and dry it in big lumps - choc bit size is the aim. When they dry, they are just the right size to drop into a test tube of H2O2. Since MnO2 is only a catalyst, it doesn't get consumed in the reaction SO the pellets are re-useable. Yay! And...no-ne gets covered in MnO2.

Thank you so much Smiley......That sounds like an amazing idea...

Let me try it out

I need a bit more information on this one!

I remember, a few years ago, that Manganese Dioxide was "disgraced" and discouraged from use. I went through my store at the time and put orange dots over all the old green dots on my bottles and I have encouraged teachers to use an alternative (like KI) instead when making Oxygen from peroxide, etc, ever since

BUT... Our new Science Text books ("Science Essentials", I think, for the Australian Curriculum) use MnO2 for junior school experiments and "Risk Assess" has no objection. My HT is of the opinion that if it is OK by Risk Assess, then it is OK, and has asked me to prove otherwise! (and apparently, "I read it on an internet forum" will NOT be accepted as a proof that will trump Risk Assess!

Can anybody help me out by directing me to "Chapter and verse" where it is written that we should not use Manganese Dioxide in Junior School experiments?

Thanks for your help
Ian

Ian, we don't allow our junior classes to use MnO2.

Taken from the CSIS page 153
Manganese (IV) Oxide or Manganese dioxide safe for 7-12 ca No 1313-13-9
Slightly toxic if ingested.
Can be used as a catalyst for the decomposition of Hydrogen peroxide solution to produce oxygen gas.
Must not be used to catalyse the thermal decomposition of potassium chlorate, which is an "X" Banned chemical since this reaction sometimes results in explosions. (See also Heavy Metal Compounds)
Note: a solution/Mixture of 25% manganese (IV) Oxide is not hazardous according to the work safe list of designated hazardous substances.

End of quote.

Also check the SDS from the manufacturer. We only have access to the original CSIS which is out of date. The SDS is the most up to date source of information for us.

We use it for junior classes but I have a small amount already deposited in the bottom of the test tube for the students to just add the hydrogen peroxide to and test for the oxygen liberated. Saves on students using a ridiculous amount of the manganese dioxide powder and all the mess!

Anastasia

I HATE cleaning beakers after this prac...

So do I! That's why the little pellets are so good....no mess.