Dropping hot charcoal into liquid oxygen :D
Why is this not exploding?
Fire needs three things; Oxygen, fuel and heat. Clearly we have those three things.
But the crux is that oxygen itself is not a fuel. And even though there is a large amount of oxygen present it isn’t in a form that can readily react with the fuel (the charcoal). The liquid oxygen is very cold, below 90 K (-180 C).
You can see in this gif how the hot charcoal vapourises a small amount of the liquid oxygen when it touches it. The expansion of the gas is enough to bounce the charcoal back into the air.
Liquid oxygen has an expansion ratio of 1:861 meaning that 1 litre of liquid oxygen will take up the space of 861 litres of oxygen gas. The vapourises oxygen is enough to set the charcoal aflame again. But not enough for an explosion.
In the rest of the video the charcoal fizzes around the surface of the oxygen like sodium on water.