Diffusion Title: Purpose: The diffusion lab was designed to allow us, as students, to see how at different temperatures water molecules increase and decrease the rate in which they move. Procedure: i) Materials (1) Three large containers, such as pitchers (2) Three clear, smooth sided glasses (3) Food coloring (4) Water (5) Stop watch or other timing device. ii) Methods (1) Fill the three containers with water - let one container stand at room temperature for 30 minutes, add ice to the second container and let it stand at room temperature for 30 minutes, reserve the third container for boiling water. (2) Place one cup (or 237 ml) room temperature water in each of the glasses. (3) Add one drop of food coloring to the first glass of water noting the time. (4) Determine the amount of time it takes for the drop of food coloring to dissipate completely in the water. (5) Repeat on the second and third glasses of room temperature water, respectively. Data: Boiling Water 59.2 sec 56 sec 1 min 05 sec Average: 1 min .0667 sec Room Temperature Water 1 min 13.4 sec 1 min 20 sec 1 min 18.6 sec Average: 1 min 17.333 sec Cold Water 1 min 57.2 sec 2 min 10 sec 2 min 03 Average: sec 2 min 3.400 sec
Results: Time in Seconds
One of the basic ways substances can get in and out of cells is by simple diffusion. Diffusion is the movement of molecules from a region of high concentration to a region of low concentration by means of random molecular motion. The transfer of kinetic energy involved in the collision causes a shift in the velocities of both molecules. The net result is each molecule seems to be moving in a random fashion. The whole group of large molecules that start out concentrated in a small area moves from the region of high concentration to a region of low concentration.
Conclusion: Diffusion in a solution can be sped up by heating the solution. This makes sense when you consider that heat is the total amount of kinetic energy in a solution. Likewise to slow diffusion down the solution can be cooled. Be careful not to confuse diffusion with convection currents caused by unequal heating of solutions or with the kind of mixing that can come about by stirring a solution. Diffusion requires kinetic energy from the environment but does not require cellular energy. Hence diffusion is a form of passive transport.