# Diffusion due to difference in partial pressure

I learnt about diffusion as the flow of component from a region of higher concentration to lower concentration. Fine, I understood this because for example , if we spray a perfume at one corner of an empty room, it has higher concentration there. soon due to molecular collisions the molecules will be evenly distributed around the room and so the fragrance of perfume.

Then I came to learn about diffusion as intermixing of particles due to partial pressure difference. This is what I couldn't understand. I know the partial pressure of a constituent of a gas mixture in a container is the pressure exerted by that constituent if same amount of that constituent was only present in the vessel at same temperature.

Please help me understand diffusion in terms of partial pressure difference.

• In a gas mixture, the partial pressure of a species divided by the total pressure is its mole fraction. Hope this helps you see the connection to concentration. Commented May 24, 2021 at 11:02

## 1 Answer

Diffusion occurs due to a concentration gradient. A "partial pressure difference" is just another way of saying that there exists a concentration gradient.

• how concentration gradient and partial pressure difference are equivalent? Commented May 24, 2021 at 4:07
• Calculate the number of molecules that occupy a given small space for two different partial pressures, then do the same for two different concentrations. The math involved is substantially the same for both calculations. Commented May 24, 2021 at 17:21