Semipermeable membranes and osmotic flow Osmosis is the process in which a liquid passes through a membrane whose pores permit the passage of solvent molecules but are too small for the larger solute molecules to pass through. The figure shows a simple osmotic cell. Both compartments contain water, but the one on the left also contains a solute whose molecules represented by blue circles are too large to pass through the membrane.
History The " endosmometer " invented by Dutrochet. Some kinds of osmotic flow have been observed since ancient times, e. In biological systems, the solvent is typically water, but osmosis can occur in other liquids, supercritical liquids, and even gases.
For example, if the cell is submerged in saltwater, water molecules move out of the cell. If a cell is submerged in freshwater, water molecules move into the cell. Water passing through a semi-permeable membrane When the membrane has a volume of pure water on both sides, water molecules pass in and out in each direction at exactly the same rate.
There is no net flow of water through the membrane. The mechanism responsible for driving osmosis has commonly been represented in biology and chemistry texts as either the dilution of water by solute resulting in lower concentration of water on the higher solute concentration side of the membrane and therefore a diffusion of water along a concentration gradient or by a solute's attraction to water resulting in less free water on the higher solute concentration side of the membrane and therefore net movement of water toward the solute.
Both of these notions have been conclusively refuted. The diffusion model of osmosis is rendered untenable by the fact that osmosis can drive water across a membrane toward a higher concentration of water.
Effect of different solutions on blood cells Micrographs of osmotic pressure on red blood cells RBC Plant cell under different environments.
It is hard to describe osmosis without a mechanical or thermodynamic explanation, but essentially there is an interaction between the solute and water that counteracts the pressure that otherwise free solute molecules would exert.
One fact to take note of is that heat from the surroundings is able to be converted into mechanical energy water rising. Many thermodynamic explanations go into the concept of chemical potential and how the function of the water on the solution side differs from that of pure water due to the higher pressure and the presence of the solute counteracting such that the chemical potential remains unchanged.
The virial theorem demonstrates that attraction between the molecules water and solute reduces the pressure, and thus the pressure exerted by water molecules on each other in solution is less than in pure water, allowing pure water to "force" the solution until the pressure reaches equilibrium. The osmotic entry of water raises the turgor pressure exerted against the cell walluntil it equals the osmotic pressure, creating a steady state.
When a plant cell is placed in a solution that is hypertonic relative to the cytoplasm, water moves out of the cell and the cell shrinks. In doing so, the cell becomes flaccid.
In extreme cases, the cell becomes plasmolyzed — the cell membrane disengages with the cell wall due to lack of water pressure on it.
When a plant cell is placed in a solution that is hypotonic relative to the cytoplasm, water moves into the cell and the cell swells to become turgid. Osmosis is responsible for the ability of plant roots to draw water from the soil.
Plants concentrate solutes in their root cells by active transport, and water enters the roots by osmosis. Osmosis is also responsible for controlling the movement of guard cells. Osmosis can be demonstrated when potato slices are added to a high salt solution.
The water from inside the potato moves out to the solution, causing the potato to shrink and to lose its 'turgor pressure'. The more concentrated the salt solution, the bigger the difference in size and weight of the potato slice.Honors Chemistry is designed for students who have demonstrated strong ability in previous science courses.
In this fast-paced, demanding course, the main topics--which include atomic theory, nuclear chemistry, periodicity, chemical reactions, stoichiometry, gases, solutions, reaction kinetics, equilibrium, acid-base theory, oxidation-reduction, and organic chemistry--are studied at an.
Colligative properties are those properties of solutions that depend on the number of dissolved particles in solution, but not on the identities of the solutes. AUS-e-TUTE is a science education website providing notes, quizzes, tests, exams, games, drills, worksheets, and syllabus study guides for high school science students and teachers.
CBSE class 12 chemistry covers aldehydes, ketones and carboxylic acids, alcohols, phenols and ethers, haloalkanes and haloarenes, biomolecules, polymers, chemistry in everyday life, amines, coordination compounds, solid state, d and f block element, electrochemistry, chemical kinetics, surface chemistry, solutions, p block elements, general principles and processes of isolation of elements.
The colligative properties really depend on the escaping tendency of solvent molecules from the liquid phase. You will recall that the vapor pressure is a direct measure of escaping tendency, so we can use these terms more or less interchangeably.
Liquid: Liquid, in physics, one of the three principal states of matter, intermediate between gas and crystalline solid.
The most obvious physical properties of a liquid are its retention of volume and its conformation to the shape of its container.
Learn more about the properties and behavior of .