Diffusion

Diffusion

Diffusion is a passive process in which particles move from an area of greater concentration to an area of lesser concentration.  This happens through random collisions of particles.  When particles collide they bounce off each other like pool balls and move in a new direction until they collide with yet another particle.  The more particles in a space (higher concentration) the more likely there are to be collisions.  The fewer particles in a space (lower concentration) the less likely there are to be collisions.  As a result, relatively many collisions occur in high concentration areas bumping particles into the low concentration zone.  Relatively few collisions occur in the low concentration areas meaning fewer particles are bumped from there to the high concentration area.  Notice particles are moving in both directions, but net movement is in the direction of high to low concentration.  Once dynamic equilibrium is met, collisions are equal on both sides and so particles are being bumped to each side at approximately equal rates.  Therefore, since particles are still moving, we say that there is no net movement in any one direction.

Image Credit: https://upload.wikimedia.org/wikipedia/commons/thumb/4/4d/DiffusionMicroMacro.gif/250px-DiffusionMicroMacro.gif

Diffusion from a microscopic and macroscopic point of view. Initially, there are solute molecules on the left side of a barrier (purple line) and none on the right. The barrier is removed, and the solute diffuses to fill the whole container. Top: A single molecule moves around randomly. Middle:With more molecules, there is a clear trend where the solute fills the container more and more uniformly. Bottom: With an enormous number of solute molecules, all randomness is gone: The solute appears to move smoothly and systematically from high-concentration areas to low-concentration areas, following Fick's laws. (https://en.wikipedia.org/wiki/Molecular_diffusion)

Go to this link "Diffusion Visualization and Practice from the Concord Consortium".  Save your reports and attach them to the assignment created in our Google Classroom.

Answer the Pre-Lab Questions in your Lab Notebook and submit your notebook to the assignment created in our Google Classroom.  Answer each question on a different slide. Find a supporting image online and paste it alongside your explanation on your slide.  Write the question as your title caption and the response as your body text.

• What is kinetic energy and how does it differ from potential energy?
• What environmental factors affect kinetic energy and diffusion?
• Why do these factors alter diffusion rates? How do they affect rates?
• How are gradients important in diffusion and osmosis?
• What is the explanation for the fact that most cells are small and have cell membranes with many convolutions?
• Will water move into or out of a plant cell if the cell has a higher water potential than the surrounding environment?
• What would happen if you applied saltwater to a plant?
• How does a plant cell control its internal (turgor) pressure?