A question! (Chemistry and Particles)

[Zakharra]

 Cherri Tart =  http://www.girlgeniusonline.com/

Question, water is made up of oxygen and hydrogen atoms. Separate, as a liquid or gas they both are extremely flame able. Why, when combined to make water, do they 1, not burn and 2, put out fires that use oxygen and hydrogen for air and fuel?

[Vekseid]

Because water has a lower energy state than individual dihydrogen or dioxide molecules. The reaction of it forming is visibly exothermic (releases energy) while splitting water up is endothermic (requires energy).

Water can burn, and does in a number of reactions, most famously with alkali metals and alkaline earth metals, because their compounds form even lower energy states than water.

In fires where this isn't going to be the case (ie with hydrocarbons in an oxygen atmosphere), water does not burn and instead can be used to suffocate the fire, preventing it from getting oxygen.

[Zakharra]

 Here's another one. Light is made of photons, I think. and nearly weightless. Supposedly nothing can travel faster than light. What makes light move?

Side question, the sound barrier was a limit that was once thought unbreakable, but it was broken. Why can't the light speed barrier be broken too?

[Vekseid]

No respectable scientist ever thought that the sound barrier couldn't be broken.  Whips and rifles both break the speed of sound.

A photon is a quantum of energy which basically represents the change in the strength of an electromagnetic field over a short period of time, the changes in which propagate at the speed of light. In this sense it is considered to be a wave, but it is obviously well known for its discrete properties such as the two-slit experiment. In short, light 'moves' because it represents the propogation of electromagnetic energy changes.

The light barrier is not a speed limit in the traditional sense, that sort of question belongs in the other thread, though :-p