Osmosis and Dialysis

Topics: Diffusion, Osmosis, Semipermeable membrane Pages: 4 (1124 words) Published: February 5, 2013
Using dialysis tubing to model diffusion of a cell membrane and investigating the influence of solute concentration on osmosis Purpose
* Discover how dialysis tubing diffuses the cell membrane * Explore the effect of solute concentration on osmosis
A cell membrane is a very significant function in the human body. In one sense, it is used as a barrier to keep the enzymes, DNA, and metabolic pathways that bundles everything together. Cell membranes are also used as a gateway for waste projects that must be discharged and essential materials (oxygen, water, etc.) must enter through it. When a membrane is called semipermeable, it means that it will allow certain molecules or ions to pass through it by diffusion and occasionally specialized facilitated diffusion. When the cell membrane expends energy, it is known as active transport, or when the process is driven by kinetic energy, it is passive transport. Hypotheses

Activity A: Diffusion
-If glucose can pass through the semi-permeable membrane, then the solution inside the dialysis tubing will test positive for glucose after 48 hours. -If starch can pass through the semi-permeable membrane, then the solution outside the dialysis tubing will turn black. -If iodine (IKI) can pass through the semi-permeable membrane, then the solution in the cup will turn black. Activity B: Osmosis

-If sucrose molarity influences osmosis then % change in mass will increase as molarity increases. Materials
* Dialysis tubing
* Plastic cup
* Glucose/starch solution
* Distilled water
* Iodine-potassium iodide (IKI) solution
* Dropping pipet
* Glucose test strips
* Funnel
Procedure A
1. Pour 160-170 mL of distilled water into a plastic cup. Add about 4 mL of IKI solution to the water and mix well. Record the initial solution color in Table 1. Dip a glucose test strip into the solution and record the initial glucose test results in Table 1. Use the + symbol to indicate a positive...
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