I noticed this happens when I open the lid of boxes that were in the fridge and accumulated water on their lids.
When I open the lid all of the droplets stay in place but as soon as I flip it vertically they all slide down and drop.
The weight of the droplet is the same, so is gravity, why are the droplets sliding down on the lid rather than staying in place like they were when it was horizontal?
In: 13
Thats a great question that demonstrates intermolecular forces and how they break.
When you have it vertically you have no intermolecular forces being broken as the water and surface are still attracted to each other due to these forces. As it moves down it simply replaces a former bond with another, so it doesn’t loose any bonds thus making it easy for it to fall.
When you have it horizontally it has to completely break the bond otherwise it won’t move. It also can’t replace these bonds as once it breaks it falls.
Either if you use a hydrophobic surface or a non-polar solvent (like acetone or hexane) it will drop immediatly when horizontally because the force of gravity is much stronger then the weak intermolecular forces the have.
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