Diffusion Lecture Notes

Introduction to Diffusion

• 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 and spread out over time until they are evenly distributed.
• Net Movement: Considers the group movement of all particles, even if individual particles occasionally move closer together.

Characteristics of Diffusion

• Occurs in Gases and Liquids:
  • Example: Perfume diffuses across a room.
  • Example: Food coloring diffuses in water.
• Passive Process: Diffusion does not require energy; it results from random particle motion.

Diffusion Across Cell Membranes

• Partially Permeable Membranes:
  • Allow only some molecules to pass through (e.g., water, glucose, amino acids).
  • Larger molecules like proteins and starch cannot pass due to size.

Factors Affecting the Rate of Diffusion

1. Concentration Gradient:
   • Defined as the difference in concentration between two areas.
   • Greater concentration gradient results in a higher rate of diffusion.
2. Temperature:
   • Higher temperatures give particles more energy, causing them to move faster.
   • Increased temperature results in a higher rate of diffusion.
3. Surface Area:
   • Larger surface areas allow more particles to diffuse simultaneously.
   • Greater surface area results in a higher rate of diffusion.

Conclusion

• Understanding diffusion helps in comprehending processes in biological systems and other chemical phenomena.
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