Teachers may require balloons filled with just air, just hydrogen, just oxygen, air and hydrogen and oxygen and hydrogen to compare the differences when ignited. This will obviously take some setting up. Gases from cylinders are required instead of chemically generated gases as it is difficult (but not impossible) to achieve sufficient pressure to inflate a balloon using the latter.
Small round party balloons should be used for this demonstration and they should not be filled too far in advance of the demonstration.
Equipment typically required (per demonstration)
Always ensure there is nothing combustible directly above the balloon or near to it on the bench.
Some of the balloons will explode with an almighty bang and so it may be useful to have a go at this demonstration first without an audience.
Students should either wear defenders or place their fingers firmly in their ears to protect them from the bang. The demonstrator should wear eye and ear protection.
The equation for this exothermic reaction is:
2H2(g) + O2(g) → 2H2O(g)
The contents of this page are for information only. Please refer to CLEAPSS, SSERC or ASE safety advice and/or publications before undertaking any preparation, practical experiment or using any equipment featured on this site or any other.