Lecture

Osmosis and Osmotic Pressure: Deriving Van't Hoff's Law

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Description

This lecture discusses the concept of osmosis and osmotic pressure, focusing on their significance in biological systems. The instructor begins by explaining the nature of semi-permeable membranes and how they selectively allow certain molecules to pass. A system is described with two compartments separated by such a membrane, illustrating how a solution of salt and water behaves differently than pure water. The lecture details the equilibrium state of the system, where the chemical potentials of the solvent equalize across the membrane, while the solute remains confined. The instructor derives the relationship between osmotic pressure and the concentration of solute, leading to the formulation of Van't Hoff's law. This law quantitatively describes how osmotic pressure can be calculated based on the concentration of solute and temperature. The lecture concludes by summarizing the final expression for osmotic pressure, emphasizing its practical applications in understanding biological processes and solutions.

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Official source

Ontological neighbourhood

Biology

Cell biology: Membrane biology

Physics

Thermodynamics: Statistical mechanics

Related concepts (32)

Osmosis

Osmosis (ɒzˈmoʊsɪs, ɒs-) is the spontaneous net movement or diffusion of solvent molecules through a selectively-permeable membrane from a region of high water potential (region of lower solute concentration) to a region of low water potential (region of higher solute concentration), in the direction that tends to equalize the solute concentrations on the two sides. It may also be used to describe a physical process in which any solvent moves across a selectively permeable membrane (permeable to the solvent, but not the solute) separating two solutions of different concentrations.

Osmotic pressure

Osmotic pressure is the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane. It is also defined as the measure of the tendency of a solution to take in its pure solvent by osmosis. Potential osmotic pressure is the maximum osmotic pressure that could develop in a solution if it were separated from its pure solvent by a semipermeable membrane. Osmosis occurs when two solutions containing different concentrations of solute are separated by a selectively permeable membrane.

Semipermeable membrane

Semipermeable membrane is a type of biological or synthetic, polymeric membrane that will allow certain molecules or ions to pass through it by osmosis. The rate of passage depends on the pressure, concentration, and temperature of the molecules or solutes on either side, as well as the permeability of the membrane to each solute. Depending on the membrane and the solute, permeability may depend on solute size, solubility, properties, or chemistry. How the membrane is constructed to be selective in its permeability will determine the rate and the permeability.

Cell membrane

The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extracellular space). The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols (a lipid component) interspersed between them, maintaining appropriate membrane fluidity at various temperatures.

Membrane technology

Membrane technology encompasses the scientific processes used in the construction and application of membranes. Membranes are used to facilitate the transport or rejection of substances between mediums, and the mechanical separation of gas and liquid streams. In the simplest case, filtration is achieved when the pores of the membrane are smaller than the diameter of the undesired substance, such as a harmful microorganism.

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