Title: Diffusion

Introduction: Background : Background : - We will use dialysis tubing as the cell membrane - It is selectively permeable (like how some things can go through a filter and others cant) - The solute is the starch in one bag and food coloring in the other. - The solvent is water. - Starch is a large molecule. - Food Coloring is a small molecule of dyed water. -Iodine will turn starch black.

Hypothesis: I think starch (will or will not) move across the membrane because:…… I think starch (will or will not) move across the membrane because:…… I think the food coloring (will or will not) move across the membrane because… I think the food coloring (will or will not) move across the membrane because… To see diffusion: movement of molecules across a membrane. Purpose:

Materials: (per group) Water with food coloring 2 Dialysis bags Iodine Starch Two beakers filled with water Two pipettes

Procedures 1. Put Iodine into beaker with water. 1. Put Iodine into beaker with water. 2. Tie a knot in one end of the dialysis tubing and fill it with starch then tie other end. 2. Tie a knot in one end of the dialysis tubing and fill it with starch then tie other end. 3. Put the bag into the iodine water. 3. Put the bag into the iodine water. 4. Take the other dialysis bag and tie one end then fill it with food coloring and tie the other end. 4. Take the other dialysis bag and tie one end then fill it with food coloring and tie the other end. Put the food coloring bag into the beaker with just water. Put the food coloring bag into the beaker with just water.

Data collection Color Starch Test Food Coloring Test Inside of the beaker before Inside of the beaker after Inside of the bag before Inside of the bag after

Conclusion Look at the data: Look at the data: 1. A) Did the starch move out of the bag and how do you know? 1. B) Did the iodine move into the bag and how do you know? 2. A) Did the Food Coloring move out of the bag and how do you know? 2. B) Did the water move into the bag and how do you know? (If you don’t know how could you find out?) 3. Did you make any mistakes and what would you do differently next time?