What happens when hydrogen bonds stretch? I'm researching about the Mpemba effect and I came across an explanation saying that the effect occurs because at higher temperatures, the hydrogen bonds between the water molecules stretch and store energy and when the water starts to cool, the hydrogen bonds go back to normal and release the stored energy on top of the normal cooling process, that's why hot water freezes faster than cold water.
I'm quite new to hydrogen bonds, so I don't really understand how hydrogen bonds can store energy. I thought bonding was something like a magnet attracting something, the further you get, the weaker the attractive force becomes. Or am I understanding it wrong?
The article that I saw this in is Hot water freezes faster than cold water; physicists solve the Mpemba effect
Yeah this question is actually surprisingly difficult to to answer.  But let me explain it this way.   In thermodynamics you can't have negative temperature.  Thus anytime you are getting heat, you are actually gaining electrons.  When you gain electrons these chemical bonds change and rearrange themselves, which is how they can store energy.
We do not think about this normally because we look at hydrogen and we just see a proton and electron.  But in reality, unless hydrogen is in an extreme environment, it likely has absorbed energy in some manner.
For instance,  if you put a glass of water under concentrated sunlight it will absorb photons, these photons will be absorbed by the moving electrons inside the atom. Which we understand as &quot;heat&quot;, moreover If there are more electrons than water molecules than it will start to evaporate because they run out of room.