Diffusion across a Selectively Permeable membrane Essay

Introduction spreading is movement of molecules from superstar area of concentration to a nonher. This process is vital for the life functions of cells. Cells fork out selectively pervious membranes that allow lonesome(prenominal) certain resolving powers to hunt down through and through them. Osmosis is a special kind of diffusion that allows water to go through semi-permeable membranes of high water potential to a region of lower water potential. Water potential measures the disposal of water to leave one stake and into another. Diffusion and osmosis is responsible for the movement of molecules in and out of cells. Diffusion and osmosis can be shown using dialysis tubing which is a membrane that is made of regenerated cellulose fibers into a flat tube. When solutions that transmit dissolved substances, are separated by a membrane like the dialysis tubing, some may right away pass through it and others may not due to the size of the molecules.HypothesisDiffusion and osmosi s will occur once dynamic equilibrium is reached. If a substance contains molecules small enough to pass through a selectively permeable membrane then they will readily pass through it without the solution or substance, which is at bottom the membrane, getting out.MaterialsStringStarch SolutionI2KI SolutionPlastic cupDisposable steer pipettesStrips of dialysis tubing soaked in waterTimerScaleMethodFirst you will have your dialysis tubing soaked in water ready for the experiment. Once the dialysis tubing in being soaked, laundry your hands to get rid of any oils or dirt that may be on them. read the tubing from the water and tie off one end. Open the other end using twain fingers in a rubbing motion so that the tubing will separate and open. Use a disposable pipette to fill the tubing with stiffen solution. Once the tubing is filled leave a bit of space so that expansion may occur and tie off the end and place the tubing on the scale to see how much it weighs. Fill the cup wit h distilled water and add I2KI solution to the water. Place the tubing inside the cup for 30 minutes and record any color change. rule book the color change of the bag every 5 minutes until 30 minutes have passed. become the tubing out of the water solution and place on the scale and record any pack change.DataSolutionsourceOriginalContentsOriginalcolorOriginalWeight5 mincolor15min color25 mincolor30 min colorFinal weightFinal ContentsBagWater 1% starchWhite/milky10gWhite slightly blueMilky inside darker blue Darker blue some white visibleDarker blue no white visible11gWater 1% starch + ace BeakerWater, I2KIAmber yellowN/AAmber YellowAmber YellowAmber YellowAmber YellowN/AWater and iodineResultsThe results show that the water, glucose, and I2KI molecules were small enough to pass through the selectively permeable membrane which was the dialysis tubing. I would expect for the color change to occur in the cup instead of inside of the tubing if we had started with the starch in the cup and the I2KI inside the tubing, because the iodine would instead of going into the bag, would leave through the bag and into the starch inside the cup.Discussion and conclusionThe data shows what molecules can and cannot diffuse across a selectively permeable membrane. The color change that occurred showed that the I2KI molecules were small enough to pass through the pores of the membrane or dialysis tubing. This data as well as shows that the water and glucose solution moved out of the dialysis bag because water molecules are small enough to pass through the membrane. No mistakes were made in this experiment but many could have occurred. If the tubing was not tied correctly a leak could have occurred and the experiment would have failed and been inaccurate.ReferencesDiffusion and Osmosis. Diffusion. N.p., n.d. Web. 19 Mar. 2014 Diffusion. And Osmosis. N.p., n.d. Web. 20 Mar. 2014.Osmosis. Osmosis. N.p., n.d. Web. 19 Mar. 2014.