Difference between Diffusion and Osmosis


Diffusion and Osmosis both of them are physical processes that are commonly mixed with each other and one can easily find difficulty to highlight difference between these two terminologies. Both of the process are found in nature and are related with motion of atoms and molecules from places of higher concentration to areas of lower concentration. These are the basic concepts that are typically taught in physics, chemistry and also biology and hold great importance in science. All processes in nature are explained on the basis of motion of atoms and molecules and these two concepts beautifully sum up all these processes at a microscopic level.



As we know that both diffusion and osmosis includes motion of molecules, so how can we compare these two terms and differentiate them from each other. While diffusion involves movement of any chemical from one area to another, osmosis involves movement of only water across a permeable membrane. So from above discussion it is cleared that it is only water that can undergo osmosis. As such we can say that osmosis is a special type of diffusion. A real life example of osmosis is when we feel thirsty after eating something salty as this salt draws water from cells of the body.

  • The process of diffusion takes place without a membrane while on the other hand osmosis takes place across a semipermeable membrane only.
  • In the process of diffusion molecules can travel in any direction, while on the other hand in the process of osmosis, molecules travel in one direction only.
  • Diffusion as a process is not restricted to liquids and even gases diffuse. One practical example of gaseous diffusion is room air freshener spray which is smelled at the other corner of the room. Osmosis can occur in solutions that are aqueous in nature or in solutions in which water is involved.
  • The process of osmosis is slower in nature while on the other hand the process of diffusion takes place at a faster rate.
  • Diffusion takes place over both short as well as long distances while on the other hand osmosis can take place over short distances only.
  • Diffusion is not dependent upon water for flow of molecules, while on the other hand osmosis occurs only if water is present or only in aqueous solution.
  • Diffusion is a process and osmosis is a special type of diffusion process.

One similarity between both osmosis and diffusion is that they are both passive in nature and no external force is necessary for the transfer of molecules from one area to another. Diffusion and osmosis both play a vital role in living organisms to attain a state of equilibrium inside. In the case of plants, osmosis is required for cell membranes to absorb the water and other liquids, while diffusion allows water, oxygen and carbon dioxide to pass through. In case of animals (including humans), osmosis is very essential as it allows for distribution of nutrients and release of waste products.

You may be interested in examples of diffusion and osmosis examples of diffusion and osmosis 

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