In a lab class, we have done the following experience:

 

1. In a watch glass was put some KMnO4 grains, then, some drops of concentrated sulfuric acid.

2. On the end of a glass rod, we put a piece of cotton and we wet it in Ethylic Alcohol.

 

Final part: We leaned the cotton on the watch glass.

 

Result: An explosion (much gas)

 

so... I cant understand what happened, what's the function of the sulfuric acid... and what are the reactions...

it makes Manganese heptoxide, it`s an extremely powerful and reactive oxidiser a good many organic materials burst into flames when in contact with it (even dust in the air).

 

look here: http://woelen.scheikunde.net/science/chem/exps/mn2o7/index.html

Thank you and thank you... that's exactly what I was looking for!

Perfect website...

I was finding lots of different answers (including this one) and this is the only which made sense.

that's great.