diffusion and osmosis

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Diffusion and Osmosis. Dissolving KMnO 4 crystal. Diffusion. Particles in a liquid or gas spread out… … from regions of high concentration… … to regions of low concentration… …until the particles are evenly spread out. High concentration gradient. Fast rate of diffusion. - PowerPoint PPT Presentation

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Diffusionand OsmosisDiffusion Particles in a liquid or gas spread out from regions of high concentration to regions of low concentration until the particles are evenly spread out.

Dissolving KMnO4 crystal The difference between the regions of high concentration and low concentration is called the concentration gradient

The steeper the concentration gradient, the faster diffusion takes place

High concentration gradientFast rate of diffusionLow concentration gradientSlow rate of diffusion Diffusion occurs because the particles in gases and liquids are moving.

Dissolving substances in water The molecules in liquid water are constantly moving

When water molecules bump into particles of a soluble substance, they stick to them

Free moving water moleculesSugar molecules in sugar lump When the water molecules move away

they carry particles of the solute with them

Adding a solute to water reduces the amount of free water molecules

Free water moleculesSolutemolecule Partially-Permeable Membranes A partially-permeable membrane will allow certain molecules to pass through it, but not others. Generally, small particles can pass throughPartially permeable membranebut large particles cannotPartially-permeable membraneMore free water molecules on this side of membraneWater-solute particle is too large to pass through membraneFree water molecules diffuse in this directionOsmosis Osmosis is the diffusion of free water molecules from a region of high concentration of free water molecules to a region of low concentration of free water molecules across a partially-permeable membrane

until they are evenly spread out.

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