Question about high school experiment
Ill quickly explain the experiment first:
My teacher took an open can with a small hole at the bottom, which was first sealed with a cork. He placed the can upside down, hole facing up, and on a block such that the box was angled and had contact to air on the big opening.
He then filled the can with hydrogen gas, took away the cork, and lit the hydrogen, which was now streaming out slowly, on fire.
It was sizzling on for a while with only a small flame at the top, but at some point, it exploded and threw the can into the air.
The teacher asked why we had to wait for an explosion, afterwards he answered by saying at the point of explosion the ideal ratio 2:1 for the reaction 2 H2 + O2 -> 2 H2O was reached, because he wanted to illustrate that reactions need concrete ratios of substances.
However, i doubt this explanation, because there doesnt seem to be a way for the flame reaching the inside because the hydrogen was constantly flowing out, and i assumed the density of hydrogen causes layer separation between air, not a mixture.
Could this have to do with the flow rate of the hydrogen or with the shape of the distribution of hydrogen in the can? Or is the teachers explanation correct?