The individual molecules travel that fast, but soon bump into other molecules. Those other molecules get bumped and speed off into still other molecules. So the molecules move very fast but don't travel very far. Eventually all of the water would mix though, which we call diffusion.
LiveNeverIdle t1_j388gxw wrote
Reply to comment by ForeverInQuicksand in How much do water molecules move around within a stationary body of water? by KpgIsKpg
The individual molecules travel that fast, but soon bump into other molecules. Those other molecules get bumped and speed off into still other molecules. So the molecules move very fast but don't travel very far. Eventually all of the water would mix though, which we call diffusion.