Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration, spreading out and equalizing the concentration gradient. This movement occurs due to the random motion of particles. To illustrate the process, let’s consider an example involving the diffusion of a gas.
Example: Diffusion of Perfume in a Room
Imagine you spray perfume in one corner of a room. Initially, the perfume molecules are concentrated in that specific area. Over time, the perfume odor spreads throughout the room, reaching all corners. This spread is a result of the process of diffusion.
Here’s a breakdown of the diffusion process in this example:
- Higher Concentration Area:
- At the beginning, the perfume molecules are densely packed in the area where you sprayed the perfume. This region represents the higher concentration of perfume molecules.
- Movement of Perfume Molecules:
- The perfume molecules are in constant motion due to their kinetic energy. They move randomly in all directions.
- Collisions and Random Movement:
- As the perfume molecules move randomly, they collide with air molecules and each other. These collisions cause the perfume molecules to change direction.
- Net Movement from Higher to Lower Concentration:
- Since the perfume molecules are initially concentrated in one corner, there is a higher likelihood of them colliding with air molecules and moving away from that area.
- Equalization of Concentration:
- Over time, as the perfume molecules move throughout the room, they disperse evenly. This equalizes the concentration of perfume molecules in the room.
- Dynamic Equilibrium:
- Once the perfume molecules are evenly distributed, they continue to move randomly, but there is no overall change in concentration. This is known as dynamic equilibrium, where the movement is still occurring but with no net change in concentration.
The key factors influencing the rate of diffusion include temperature, the size of the molecules involved, and the medium through which the diffusion occurs. In the perfume example, the diffusion process is facilitated by the random motion of perfume molecules and their collisions with air molecules, leading to the gradual spread of the perfume odor throughout the room.
References
Vosburgh, D. J. H., Ku, B. K., & Peters, T. M. (2014). Evaluation of a Diffusion Charger for Measuring Aerosols in a Workplace. Annals of Occupational Hygiene, 58(4), 424–436. https://doi-org.proxy.mul.missouri.edu/10.1093/annhyg/met082
Cooper, C. W., Aithinne, K. A. N., Stevenson, B. S., Black, J. E., & Johnson, D. L. (2020). Comparison and evaluation of a high volume air sampling system for the collection of Clostridioides difficile endospore aerosol in health care environments. American Journal of Infection Control, 48(11), 1354–1360. https://doi-org.proxy.mul.missouri.edu/10.1016/j.ajic.2020.04.014
Nursing Notes 