Definition: Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration.
Key Idea: Molecules move randomly; over time, they spread out until evenly distributed across available space.
Net Movement: Refers to the overall movement of particles as a group, despite random individual movements.
Diffusion in Gases and Liquids
Gases: Example includes how perfume spreads throughout a room.
Liquids: Example includes food coloring dispersing in water until evenly colored.
Diffusion Through Cell Membranes
Cell Membranes: Act as barriers where diffusion occurs but are partially permeable.
Molecule Size:
Small molecules (e.g., water, glucose, amino acids) can diffuse through.
Large molecules (e.g., proteins, starch) cannot pass through.
Passive Process: Does not require energy input from the cell; driven by random movement of particles.
Factors Affecting Rate of Diffusion
Concentration Gradient
Definition: Difference in concentration between two areas.
Effect: Larger concentration gradient results in a higher rate of diffusion.
Temperature
Effect: Higher temperatures give particles more energy, increasing their movement speed and the rate of diffusion.
Surface Area
Effect: Larger surface area allows more particles to diffuse at once, increasing the rate of diffusion.
Conclusion
Summary: Understanding diffusion involves knowing its definition, how it applies to different states and conditions, and the factors affecting the rate of diffusion.
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