Gas Diffusion Results

Although gaseous molecules travel at tremendous speeds (hundreds of meters per second), they collide with other gaseous molecules and travel in many different directions before reaching the desired target. At room temperature, a gaseous molecule will experience billions of collisions per second. The mean free path is the average distance a molecule travels between collisions. The mean free path increases with decreasing pressure; in general, the mean free path for a gaseous molecule will be...

Gas exchange, the intake of molecular oxygen (O2) from the environment and the outflow of carbon dioxide (CO2) into the environment, is necessary for cellular function. Gas exchange during respiration occurs largely via the movement of gas molecules along pressure gradients. Gas travels from areas of higher partial pressure to areas of lower partial pressure. In mammals, gas exchange occurs in the alveoli of the lungs, which are adjacent to capillaries and share a membrane with them. When the...

Cell Membranes and Diffusion In order to function, cells are required to move materials in and out of their cytoplasm via their cell membranes. These membranes are semipermeable, meaning that certain molecules are allowed to pass through, but not others. This movement of molecules is mediated by the phospholipid bilayer and its embedded proteins, some of which act as transport channels for molecules that otherwise would not be able to pass through the membrane, such as ions and carbohydrates.

Diffusion in Agar ExpandNOTE: In this exercise, you will be given agar containing an indicator chemical called phenolphthalein. When phenolphthalein is exposed to the normal alkaline conditions in the agar, it will look pink. But when it is exposed to neutral or acidic conditions, it changes from pink to clear. You will make different size and shaped agar cubes as a model for cells to study the impact of cell size and shape on diffusion rate. To make the first set of cells, measure out and cut...

Preparation of Solutions for the Agar Cube Experiment ExpandIMPORTANT: Wear gloves, goggles, and appropriate personal protective equipment – chemicals can be hazardous at high concentrations. For the diffusion indicator solution, weigh out 1 g of phenolphthalein and add it to a beaker containing 100 mL of 95% ethanol. To make the basic solution for the agar, measure 80 mL of water into a beaker, and then add 0.4 g of NaOH. Stir until the solute is dissolved then bring the total volume of the...