Why reactions take place? H2 and O2 react to form water, then why not H2 an do2 around us in the air react?

Answer 1

its easy... for any reaction to take place there needs to be a certain temperature and proper conditions like pressure etc.. for instance think why water does mnot evaporate on its own....because it needs heat or it has to reach 100 c for evaporation... this in chemistry we call it as an activation energy. for each and every process there exixts an energy of activation for the reaction to be feasible... similarly here too for the reaction to take place we need higher pressure and some initiator like a spark.. without that these molecules can't react to form products.. hence it is absoultely essential that the conditions suit the reaction...see another example... haber's process where without enough pressure the product formation is very very small... of why does fusion take place on the sun and not on earth...(not only due to H2 but also due to temp).so unless these conditions are not satsfied the products will not be formed ... hence that is the reason why h2 and o2 do not combine to form water

Answer 2

There must be the proper number of atoms. For instance, in H2O, you need two hydrogen atoms for each oxygen atom. Hydrogen gas (H2) is there, but oxygen gas (O2), is available while oxygen itself (O) is not. Oxygen gas doesn't naturally separate itself; you need a special process to make water when you have oxygen and hydrogen. It's the reverse of electrolysis, which is when you run an electrical current through the water to get oxygen gas and hydrogen gas.
As for reactions other than water, the same applies. You need to have the exactly appropriate reactants in order for the desired product and reaction to occur. Like I said, oxygen gas (O2) is different than just the element oxygen (O). There are so many elements and therefore so many different combinations that one should be careful when expecting a reaction among a selected few.

Answer 3

Primarily because there is so little hydrogen in our atmosphere. The Earth's atmosphere is 78% Nitrogen, 20% Oxygen, 1.95% miscellaneous other gases, and 0.05% Hydrogen. At our atmospheric pressure, the likelihood of a reaction between hydrogen and oxygen is very remote, even assuming that the necessary ignition spark is present when the gas molecules collide in proper stoichiometric quantities. It would be like starting two cars driving on random routes, one in London and the other in Los Angeles, then waiting for them to hit one another.

Answer 4

The activation energy for the reaction does not occur under normanl atmosphreic conditions. We must provide a "spark" of energy. Plus there is only a tiny percentage of atmoshperic hydrogen, as its molecular velocity is greater the the gravitational pull, therefore most of it just goes into space.

Answer 5

they are reliable in a experience yet a water molecule is way extra reliable than an oxygen and hydrogen molecule aside. Molecules have a tendency to bypass in route of larger stability. stability is determined by using thermodynamic factors which contain loose enrgy to boot as kinetic factors which contain the speed of reaction.

Answer 6

it takes effort to get them to react because they are happy as diatomic molecules

Answer 7

Because someone levitated

Answer 8

because they want lower energy