The average speed of a perfume vapor molecule at room temperature may be about 300m s but youll find the speed at which the scent travels across the room is much less Why?

Answer 1

First off, let me preface this by stating I have no official source, Im just working off my body of scientific knowledge.

When you spray perfume, the molecules leave the bottle in essentially random directions, colliding with other gaseous molecules in a very intricate array of collisions.

For you to perceive a smell, molecules from the perfume have to travel from the bottle, up your nose, and into olfaction receptors. Also take note that there are thresholds for perception, ie it is very unlikely one molecule of perfume will trigger a synaptic response for perception to occur, so MANY molecules have to reach your olfaction receptors.

Your nostrils have a small surface area compared to all the other surfaces in the room, so you have to wait until random motion throws enough perfume molecules in your nose for it to be detected.

Hope this helps,

Jay