# How long do the bonds in a molecule hold under nominally stable conditions?

Disclaimer: I am not a chemist

I was just drinking my Ice Age mineral water which is 'untouched since the Ice Age' and wondered if the bonds formed in each molecule have remained intact for all those years.

In a liquid that is just lying there underground I'm guessing that there is some, if not very energetic, movement of the molecules. What happens when they bump into each other? Might an atom become dislodged and bind with another molecule?

I have no idea but the thought interested me.

• Unless there is nothing to break them, they will be intact. Nothing breaks on its own if it is not disturbed. Once stable, always stable. – Rohinb97 May 7 '15 at 13:04
• It bothers me, seeing so many questions with the disclaimer "I am not a chemist". We all have something new to learn however far we have come along the way toward "being a chemist". – iad22agp May 7 '15 at 16:01

Water with its fluctuating hydrogen bond networks is a special case. If you feel for it, have a look at Water clusters: Untangling the mysteries of the liquid, one molecule at a time, but it doesn't answer your question ;-)

It is more interesting to have a look at paleochemical/geobiological findings.

A complex organic molecule, such as 2$\alpha$-methylhopane was isolated from

2700-million-year-old shales from the Pilbara Craton, Australia (Source)

Have look at the website of Roger Summons at MIT and his freely available publications, such as The Exceptional Preservation of Interesting and Informative Biomolecules.

In short, bonds can last a pretty long time!

If you are asking about the water molecules themselves (and not some other materials present such as the paleochemical structure above) the answer is that at least for liquid water, each water molecule exchanges its hydrogen atoms with other water molecules at an extremely rapid pace (millions of times per second). While frozen (a mile deep in Antarctica or Greenland?) for millions of years, this exchange process would be slower, but still I would venture that the water molecules individually are not the same ones they were way back when. Depending on how it was handled after the ice was mined from its glacier, the sample may still be collectively composed of the same atoms that were there millions of years ago.

• This is exactly what I was wondering about but am surprised to hear that the atoms move 'millions of time per second'. Now I'm wondering why that happens - in spite of me not being a chemist ;-) Is it due to collisions or to some electrical force... ? – paul May 8 '15 at 5:42
• There are at least two factors that contribute to the rapid exchange of hydrogen atoms in water (or when bonded to an oxygen atom in other species like alcohols). Firstly, there is a small amount of ionization of water at any given point in time where two water molecules react to give hydronium ion (H3O+) and hydroxide ion (OH-). Once formed, these species could recombine to give two waters, but are more likely to react with other water molecules to exchange hydrogen atoms. – iad22agp May 8 '15 at 15:57
• A second factor is hydrogen bonding - where the hydrogen of one water forms a partial bond to the oxygen of another. This lowers the energy barrier to exchange of hydrogen atoms and makes it a more rapid process than it would be otherwise. Hydrogen is unique in chemistry because it is so small - a hydrogen ion (H+) is a bare proton and can do things other ions cannot do. – iad22agp May 8 '15 at 16:00