What is the difference between diffusion and osmosis?
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diffusion = Main Entry: dif·fu·sion
Pronunciation: di-'fyü-zh&n
Function: noun
Date: 14th century
1 : the action of diffusing : the state of being diffused
2 : PROLIXITY, DIFFUSENESS
3 a : the process whereby particles of liquids, gases, or solids intermingle as the result of their spontaneous movement caused by thermal agitation and in dissolved substances move from a region of higher to one of lower concentration b (1) : reflection of light by a rough reflecting surface (2) : transmission of light through a translucent material : SCATTERING
4 : the spread of cultural elements from one area or group of people to others by contact
5 : the softening of sharp outlines in a photographic image
- dif·fu·sion·al /-'fyü-zh&-n&l/ adjective
osmosis = Main Entry: os·mo·sis
Pronunciation: äz-'mO-s&s, äs-
Function: noun
Etymology: New Latin, short for endosmosis
Date: 1867
1 : movement of a solvent through a semipermeable membrane (as of a living cell) into a solution of higher solute concentration that tends to equalize the concentrations of solute on the two sides of the membrane
2 : a process of absorption or diffusion suggestive of the flow of osmotic action; especially : a usually effortless often unconscious assimilation <learned a number of languages by osmosis —Roger Kimball>
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Diffusion and osmosis are both types of passive transport, but they occur through different mechanisms. Diffusion is the movement of molecules from an area of high concentration to an area of low concentration. It occurs due to the random motion of particles and does not require any energy input.
Osmosis, on the other hand, is the movement of water molecules across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration. It is driven by the concentration gradient of solute molecules and also does not require energy.
To understand the difference conceptually, imagine a container divided into two compartments by a permeable membrane. If there are more solute molecules on one side of the membrane, water molecules will diffuse or osmose to that side until the concentration becomes equal on both sides. In diffusion, any type of molecule can move, while osmosis specifically refers to the movement of water molecules.
To experimentally distinguish between diffusion and osmosis, you can perform a simple experiment using a beaker of water and a selectively permeable membrane, such as a dialysis membrane. Place a solute (such as salt or sugar molecules) inside the dialysis tube, then immerse it in the beaker of water. If water molecules move across the membrane into the dialysis tube, you are observing osmosis. If the solute molecules themselves move from the dialysis tube into the surrounding water, you are witnessing diffusion.