What Happens to hot Water Molecule?

Hello. I'm a university student. I was wondering about a thing. Maybe this question might sound stupid but i hope someone can answer it for me. What will happen to the molecule of water if it is heated above it's boiling temperature for a long period of time (let's say 100 years) ? Will the molecules change ? Or will there be no difference than when it is boiled normally ? Thanks in advance.
- Khairul syamil (age 19)
Kuala lumpur, Malaysia

Interesting question. Let's say the water molecule has boiled into a vapor that is kept in a sealed inert container at say 110°C.  Mostly, the molecule will spend the 100 years just bouncing around hitting similar molecules. Nothing much interesting will happen. In liquid water, occasionally an H⁺ will get knocked off leaving OH^-, but then it will be replaced by another H⁺. In the gas that is still possible in principle but almost never happens, because it takes too much energy to separate the charges in empty space. The molecules will spend some time in excited internal states, which they can enter or leave by absorbing or emitting infrared photons that are present at that temperature. It's that very process which accounts for the major role of water in the greenhouse effect.

In the end, it will still just be water. Of course if the container is a bit reactive, other things can happen, but if it's made out of something like good teflon, reactions should be very rare.

Mike W.

(published on 02/24/2015)