Title:Title:DiffusionDiffusion

Introduction:Introduction: Background :Background :- We will use dialysis tubing as the cell We will use dialysis tubing as the cell

membrane - It is selectively permeable (like membrane - It is selectively permeable (like how some things can go through a filter and how some things can go through a filter and others cant) others cant)

- The solute is the starch in one bag and food The solute is the starch in one bag and food coloring in the other.coloring in the other.

- The solvent is water.The solvent is water.- Starch is a large molecule.Starch is a large molecule.- Food Coloring is a small molecule of dyed Food Coloring is a small molecule of dyed

water.water.

-- Iodine will turn starch black.Iodine will turn starch black.

Hypothesis:Hypothesis: I think starch (will or will not) move I think starch (will or will not) move

across the membrane because:……across the membrane because:…… I think the food coloring (will or will I think the food coloring (will or will

not) move across the membrane not) move across the membrane because…because…

To see diffusion: movement of molecules across a membrane.

Purpose:

Materials: (per group)Materials: (per group)

Water with food coloring2 Dialysis bagsIodineStarchTwo beakers filled with waterTwo pipettes

ProceduresProcedures

1. Put Iodine into beaker with water.1. Put Iodine into beaker with water. 2. Tie a knot in one end of the dialysis 2. Tie a knot in one end of the dialysis

tubing and fill it with starch then tie other tubing and fill it with starch then tie other end.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 4. Take the other dialysis bag and tie one

end then fill it with food coloring and tie the end then fill it with food coloring and tie the other end.other end.

Put the food coloring bag into the beaker Put the food coloring bag into the beaker with just water.with just water.

Data collectionData collection

ColorColor Starch TestStarch Test Food Food Coloring Coloring TestTest

Inside of the Inside of the beaker beforebeaker before

Inside of the Inside of the beaker afterbeaker after

Inside of the Inside of the bag beforebag before

Inside of the Inside of the bag afterbag after

ConclusionConclusion Look at the data:Look at the data:

1. A) Did the starch move out of the bag 1. A) Did the starch move out of the bag and how do you know?and how do you know?

1. B) Did the iodine move into the bag 1. B) Did the iodine move into the bag and how do you know?and how do you know?

2. A) Did the Food Coloring move out of 2. A) Did the Food Coloring move out of the bag and how do you know?the bag and how do you know?

2. B) Did the water move into the bag and 2. B) Did the water move into the bag and how do you know? (If you don’t know how do you know? (If you don’t know how could you find out?)how could you find out?)

3. Did you make any mistakes and what 3. Did you make any mistakes and what would you do differently next time?would you do differently next time?