This demonstration shows the explosive nature
of stoichiometric mixtures of flammable gases. It can be used during lessons on
combustion, hydrocarbons and avogadro's law. I use it most commonly
in lessens on balancing equations when it is a reward
for students who've correctly balanced the equation showing the complete combustion of methane.
As an extension for those students who already know about Avogadro's law,
you could use it as a challenge to ask where the expansion comes from
as three moles of gaseous reactants produced three moles of gaseous products.
In order to use the methane rocket experiment we recommend that you use
a strong plastic bottle of approximately 300 to 500 centimeters cubed capacity.
A carbonated drinks bottle
is a good example of a strong bottle.
First you need to find the exact volume of the bottle,
and then you should replace exactly one third of the water into the bottle
and mark this level on the outside of the bottle
using a waterproof pen.
replace a further third of the volume of the the water in to the bottle,
and again mark the level on the outside of the bottle
to indicate two thirds of the capacity of the bottle.
finally completely fill the bottle with water.
Now you're in a position to displace two thirds of the volume of the bottle
using oxygen and one third of the bottle using methane.
the oxygen supply
could be from an oxygen cylinder or from a canister of oxygen,
which is easily available on the Internet.
Ensure that air is displaced from the delivery tube
before starting to collect oxygen in the bottle.
Again, ensure the air is displaced from the delivery tube
before starting to collect methane in the bottle.
You should then secure the neck of the bottle using a rubber bung.
Ready for detonation.
It's essential that the demonstrator wears ear and eye protection.