Diffusion in Baggie

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Diffusion Lab KEY

This key goes with worksheet students use for the classroom activity: Diffusion in a Baggie. A comprehensive guide can be found at the blog article on diffusion. Photos on this page will help with the set up, procedure and explanation of results.

Prelab Observations: Describe what happened when iodine came into contact with starch.

the orange iodine combines with the white starch, turns purple

Procedure:

Fill a plastic baggie with a teaspoon of corn starch and a half a cup of water tie bag. (This may already have been done for you)

Fill a beaker halfway with water and add ten drops of iodine.

Place the baggie in the cup so that the cornstarch mixture is submerged in the iodine water mixture.

Wait fifteen minutes and record your observations in the data table

While you are waiting, answer the questions.

Questions:

1. Define diffusion. movement of molecules from an area of high concentration to an area of low concentration

2. Define osmosis diffusion of water

3. What is the main difference between osmosis and diffusion osmosis involves water, diffusion can be in air

4. Why is iodine called an indicator? because it turns color in the presence of starch, it indicates

5. Molecules tend to move from areas of __high_ concentration to areas of _low___ concentration.

What's in the Bag?

We're going to think about concentrations now, which substances are more or less concentrated depends on which one has the most stuff in it.

1. Is the baggie or beaker more concentrated in starch? baggie

2. Is the baggie or beaker more concentrated in iodine? beaker

3. Iodine solution: is the baggie or the beaker hypertonic? beaker

4. Starch solution: is the baggie or the beaker hypertonic? baggie

5. Which one is hypotonic in relation to starch, baggie or beaker? beaker (hypo means less, beaker has less starch)

Make Some Predictions

1....