complete combustion of Hydrogen and Oxygen
The ratio of H and O is 2:1 in water. If we put the correct amounts of H2 and O2 in the balloon to start with, the reaction is much closer to a complete combustion. Usually, the hydrogen nees to pull oxygen from outside the balloon and it makes for a much less aggressive explosion. This is done by a TEAM of experienced science teachers FAR away from children, buildings, and homes.