Introduction:
Diffusion is movement of molecules from one area of concentration to another. This process is vital for the life functions of cells. Cells have selectively permeable membranes that allow only certain solutions to pass 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 tendency of water to leave one place 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 contain dissolved substances, are separated by a membrane like the dialysis tubing, some may readily pass through it and others may not due to the size of the molecules.
Hypothesis:
Diffusion and osmosis 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 inside the membrane, getting out.
Materials:
The Essay on Diffusion and Osmosis Shown In Solutions
This lab, title Diffusion and Osmosis, was centered around the diffusion across a cellular membrane and how exactly materials move and diffuse in concentrations. Both diffusion and osmosis are forms of movement that are part of passive transport dealing with cell membranes. Diffusion is where the solutes move from an area of high concentration to a low concentration. Water goes through the cell ...
String
Starch Solution
I2KI Solution
Plastic cup
Disposable transfer pipettes
Strips of dialysis tubing soaked in water
Timer
Scale
Method:
First you will have your dialysis tubing soaked in water ready for the experiment. Once the dialysis tubing in being soaked, wash your hands to get rid of any oils or dirt that may be on them. Remove the tubing from the water and tie off one end. Open the other end using two fingers in a rubbing motion so that the tubing will separate and open. Use a disposable pipette to fill the tubing with starch 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 with distilled water and add I2KI solution to the water. Place the tubing inside the cup for 30 minutes and record any color change. Record the color change of the bag every 5 minutes until 30 minutes have passed. Take the tubing out of the water solution and place on the scale and record any weight change.
Data:
Solution
sourceOriginal
ContentsOriginal
colorOriginal
Weight5 min
color15
min color25 min
color30 min colorFinal weightFinal Contents
BagWater 1% starchWhite/
milky10gWhite slightly blueMilky inside darker blue Darker blue some white visibleDarker blue no white visible11gWater 1% starch + iodine BeakerWater, I2KIAmber yellowN/AAmber YellowAmber YellowAmber YellowAmber YellowN/AWater and iodine
Results:
The 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 conclusion:
The 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 also 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.
The Essay on Water 5
Thesis Statement: Water is the most crucial part of life its self, and must never go unnoticed. I. People frequently overlook the importance of water in the body. In order to keep the body healthy, people must consume water. A healthy body is a well-hydrated body. Without the constant consumption of water the body becomes dehydrated. Perhaps people overlook waters importance, simply because its ...
References
“Diffusion 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.
