Sciencemadness Discussion Board

heating manganese dioxide in air

shaheerniazi - 30-11-2013 at 04:07

I acquired some manganese dioxide from a 9 volt battery and wikipedia says that if you heat it to below 800 celsius then it decomposes to its alpha form mangasese(III)oxide or dimanganese trioxide.

When I did that the result was a brown powder, was it dimanganese trioxide?

[Edited on 30-11-2013 by shaheerniazi]

gsd - 30-11-2013 at 06:54

Heating MnO2 at high temperature converts it into lower oxidation states by releasing O2

4MnO2 -----> 2Mn2O3 + O2

3MnO2 -----> Mn3O4 + O2

BTW if your MnO2 is from battery, then it is mixed with appreciable quantity of carbon which will on heating yield:

2MnO2 + C ------> 2MnO +CO2

The easy test is react that brown powder with dilute H2SO4, if vigorous reaction happens then appreciable quantity of MnO is present.

gsd

shaheerniazi - 30-11-2013 at 07:08

but MnO is green.

shaheerniazi - 30-11-2013 at 07:53

My looked like this:



http://i40.tinypic.com/vxi6tl.jpg

http://i44.tinypic.com/2zqfsyh.jpg

I wonder what those silver flakes are in the third pic, are those manganese flakes:D