Step 9: What's going on?
The funny thing is, that when the hydrogen and oxygen-bubbles are put together again, they won’t re-unite into water-molecules all by themselves. They must be given a little ‘push’ to do that. When 'pushed' (for instance with a spark or a flame), oxygen and hydrogen will bond again as water-molecules, with a loud crack and some heat as a thank you.
The heat that is produced when hydrogen and oxygen are combined to water, makes rockets launch. The large clouds that appear when rockets launch, are made of pure and plain water. The large tanks that are mounted under the space shuttle contain hydrogen and oxygen seperately. So, somewhere at Nasa, there must be a BIG Ballistic Bubble Machine.
Q's and A's, from the top down
There's a lot to tell about what's happening when cracking knalgas-bubbles. The questions and answers below are a sort of cascade: The answer to the first question gives rise to another question, and so on...
Q: Where does the crack come from, when the bubbles are lighted?
A: What happens during the crack is an extermely fast reaction between one oxygen (O2) molecule and two hydrogen (H2) molecules. During this reaction, two water-molecules (H2O) and energy are formed. The energy that “emerges” during the reaction causes the crack you hear.
In shorthand, the reaction looks like this:
1 O2 + 2H2 → 2 H2O + energy
In a picture, it looks like pic numer 3.
Q: Why is the reaction so extremely fast, then?
A: The reaction can happen so fast, because in the gasbubbles there is exactly one oxygen molecule present for every two hydrogen-molecules. So after the reaction, there will be no oxygen or hydrogen left. Such a mixture of gasses is called a stoichiometric mixture. In dutch, it's called an "explosive mixture".
Q: So where does this "explosive mixture" of hydrogen and oxygen come from?
A: The oxygen and hydrogen come from the water inside the jar. Water is a "compound" of two atoms hydrogen and one atom oxygen: H2O. In the jar, the water-molecules are decomposed into hydrogen and oxygen. There will be twice as much hydrogen as oxygen, because water contains two hydrogen-atoms and only one oxygen-atom.
Both hydrogen and oxygen are gasses at "normal" temperatures, so they form bubbles of gas that escape the jar through the tube.