Monday, 22 June 2015


There isn't actually a genie in the bottle it's science but it's very magical to watch!  This is a great one to do with older kids or as a demonstration for younger children.


Manganese dioxide (MnO2) is a catalyst that will decompose hydrogen peroxide into water and oxygen gas.
2H2O2 + MnO2 --> 2H2O + O2 + MnO2 where MnO2 is the catalyst.


We can make this look rather spectacular but you will need to take safety precautions: Goggles, gloves, protective clothing and closed toed shoes.  Also, it’s best to do this in a well ventilated area. 

Although the products produced in this experiment are oxygen and water, it produces a lot of oxygen and oxygen is highly flammable, so take care. 

The catalyst used in this experiment is called manganese dioxide which is dangerous to touch so use gloves, it is extremely dangerous to consume, if eaten ring immediately for medical advice, if the dust is inhaled and the person who inhaled the dust struggles to breathe provide oxygen and call for medical advice.

The hydrogen peroxide in this experiment is much stronger than the sort you buy from the chemist, this strength would quickly burn your skin or eyes so be very careful when handling it.

This is also an exothermic reaction.  This means that during the experiment heat it produced.  Do not touch the bottle!!!!

Now for the fun…


Equipment and chemicals required to do this yourself:

  • A heat proof bottle - If you use a wine bottle or similar instead, for safety reasons (as it won’t be heat proof and may shatter, tape it up first.  I advise using some heat resistant tape to avoid sharp glass from exploding nearby.

  • Hydrogen peroxide 35% 
  • Manganese dioxide
  • A piece of toilet tissue
  • A 20-30cm piece of cotton thread
  • A cork at the fits your bottle.


Put 20ml of hydrogen peroxide into your bottle.  Make sure you prepare it with tape if you are unsure if it is heat proof. 


Wrap your manganese dioxide in a single piece of tissue paper, carefully and using gloves.  Close it tight with a piece of thread, about 20-30cm long.  Make sure it’s secure.  If the manganese dioxide gets on your hands wash it of immediately.


So that the manganese hovers above the hydrogen peroxide, put the cork in with the manganese dioxide covered in tissue about 5-10 centimetres in the bottle.  Put the cork on to keep it from falling in.


Ask your friend if they’d like to see a genie.  Ask them to take the cork off and then watch the show!

This is another form of decomposition of hydrogen peroxide but instead of seeing bubbles, we see steam and lots of it.        

As soon as the Manganese dioxide, the catalyst, is added it will decompose hydrogen peroxide into water and oxygen gas.

Here is the chemical formula:

2H2O2 + MnO2 --> 2H2O + O2 + MnO2

MnO2 is the catalyst, therefore chemically unchanged.


  1. Where do you get your 35% H2O2 as you need a licence to get anything stronger than 9 or 11 % nowadays?