Submitted by KpgIsKpg t3_104vosk in askscience
Let's say you leave a glass of water on a table. Over time, would you expect the water molecules to move around or would they tend to stay in the same relative position in the glass? I imagine there could be random walk behaviour where in each unit of time an individual molecule has a small chance of being jostled out of its position and pushed up or down.
cpbayern24 t1_j37vbwz wrote
If you're talking about individual water molecules, they should be moving at very high speeds (average speed should be around 500 m/s at 20C) while breaking and reforming H bonds with other water molecules. However they do stay in their relative position when water freezes.