浸透の定義、例、および事実

Osmosis | Definition, Examples, & Facts | Britannica Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos osmosis Introduction References & Edit History Quick Facts & Related Topics Images & Videos Contents CITE verified Cite While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions. Select Citation Style MLA APA Chicago Manual of Style Copy Citation Share Share Share to social media Facebook X URL https://www.britannica.com/science/osmosis Feedback External Websites Feedback Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login). 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External Websites Salt Lake Community College - College Biology I - Osmosis The Royal Society Publishing - Royal Society Open Science - Dynamics of osmosis in a porous medium Khan Academy - Osmosis National Center for Biotechnology Information - PubMed Central - The physical basis of osmosis Open Oregon Educational Resources - Passive Transport: Osmosis Chemistry LibreTexts - Osmosis American Physiological Society - Advances in Physiology Education - Measuring osmosis and hemolysis of red blood cells White Rose Research Online - Mathematical Model of Coupled Dual Chemical Osmosis Based on Mixture-Coupling Theory Rockefeller University Press - Journal of General Physiology - The physical basis of osmosis Britannica Websites Articles from Britannica Encyclopedias for elementary and high school students. osmosis - Student Encyclopedia (Ages 11 and up) osmosis An example of osmosis occurs when a sugar solution and water, top, are separated by a semipermeable membrane. The solution's large sugar molecules cannot pass through the membrane into the water. Small water molecules move through the membrane until equilibrium is established, bottom. (more) osmosis chemical process Ask Anything Homework Help Also known as: osmose Written and fact-checked by Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Britannica Editors Last updated Apr. 28, 2026 • History Britannica AI Ask Anything Table of Contents Table of Contents Ask Anything osmosis , the spontaneous passage or diffusion of water or other solvents through a semipermeable membrane (one that blocks the passage of dissolved substances—i.e., solutes). The process, important in biology , was first thoroughly studied in 1877 by a German plant physiologist, Wilhelm Pfeffer . Earlier workers had made less accurate studies of leaky membranes (e.g., animal bladders ) and the passage through them in opposite directions of water and escaping substances. The general term osmose (now osmosis ) was introduced in 1854 by a British chemist , Thomas Graham . How do plants absorb water and nutrients? Video showing how roots take up substances from the soil via osmosis, diffusion, and active transport. (more) See all videos for this article If a solution is separated from the pure solvent by a membrane that is permeable to the solvent but not the solute, the solution will tend to become more dilute by absorbing solvent through the membrane. This process can be stopped by increasing the pressure on the solution by a specific amount, called the osmotic pressure . The Dutch-born chemist Jacobus Henricus van ’t Hoff showed in 1886 that if the solute is so dilute that its partial vapour pressure above the solution obeys Henry’s law (i.e., is proportional to its concentration in the solution), then osmotic pressure varies with concentration and temperature approximately as it would if the solute were a gas occupying the same volume. This relation led to equations for determining molecular weights of solutes in dilute solutions through effects on the freezing point , boiling point , or vapour pressure of the solvent. Key People: Henri Dutrochet Hugo von Mohl Wilhelm Pfeffer Isidor Traube (Show more) Related Topics: osmotic pressure diffusion reverse osmosis solvent semipermeable membrane (Show more) On the Web: Khan Academy - Osmosis (Apr. 28, 2026) (Show more) See all related content While osmosis naturally moves solvents across a membrane from the side of higher concentration to the side where the concentration is lower, the application of pressure in reverse osmosis forces the solvent to flow in the opposite direction—against the concentration gradient—thus resulting in the filtration of the solute from the solvent, leaving behind the solutes. The membrane allows passage of small solution components, such as fresh water, while preventing passage of larger molecules , like salts and other impurities. Reverse osmosis is an effective means of concentrating impurities, recovering contaminated solvents, cleaning up polluted streams, and desalinizing seawater and is often used as an alternative to distillation for water purification . More From Britannica chemical analysis: Osmosis The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Erik Gregersen .