Supersonic Detonation of Hydrogen and Oxygen

Chief Scientist Carl Nelson demonstrates how the combustion of hydrogen gas depends on the amount of oxygen present.

A balloon filled with 100% hydrogen is ignited with a small flame. As the flame ignites the hydrogen gas, it combines with oxygen in the surrounding air. A large, but relatively slowly moving ball of fire is created. This is called a deflagration.

Next, a mixture of two parts hydrogen and one part oxygen gas is used to create a foam of soap bubbles. The amount of oxygen available here makes a significant difference in the size and sound of the reaction.

2 H2(g) + O2(g) → 2 H2O(g) + Energy

This reaction proceeds so quickly (a detonation) that a supersonic shock wave is generated. The sound level is significantly louder and the ball of flame generated is much smaller. Note that the final product of the reaction is water and energy.