H2 + O2 fusion or not?

Question

when you have hydrogen and oxygen in the same environment do they automatically fuse or do you have to supply some form of energy for it to combine

if you have an amount of hydrogen and half that amount of oxygen in the same container will it combine to form water automatically or do you have to electrocute it or something

Answer 1

The reaction is not spontaneous. You have to provide some initiatioin - usually a spark or flame. I am sure that you have seen the laboratory preparation of hydrogen gas from zinc and hydrochloric acid. I am sure that during this demonstration quite a large quantity of hydrogen gas escaped to the oxygen containing atmosphere. What happened? nothing. That answers your question.

Answer 2

without energy or a catalyst there will be no reaction. With the enzyme catalase the reaction occurs instantaneously at room temperature. That says you will have a sort of explosion.

Answer 3

it reacts  to give water. when the ratio is 50:50 it burns with a pop sound. reaction is exothermic.