What about the solution in the beaker?

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Two beakers A and B contain plain water and concentrated sugar solution respectively. Equal number of dried raisins are kept in them for some time and then taken out.a. Explain the reason for the difference in their physical appearance.b. Categorise the two solutions as Hypotonic and Hypersonic.

Visking tubing experiment

The Visking tubing is the selectively permeable membrane. Water moves by osmosis from the high water concentration (dilute solution) in the beaker into the low water concentration (concentrated solution) in the Visking tubing across the membrane, increasing the volume of liquid in the Visking tubing, which forces liquid up the capillary tube.

Diffusion Lab

Introduction: In this lab you will observe the diffusion of a substance across a semi-permeable membrane. Iodine is a known indicator for starch. An indicator is a substance that chances color in the presence of the substance it indicates. 

Pre-lab Observations: Describe what the concept of a “semi-permeable membrane.’

 Procedure:

1. Fill a plastic baggie with a teaspoon of corn starch and a half a cup of water and seal the bag. 
2. Fill a beaker halfway with water and add ten to twenty drops of iodine, until the water changes color.
3. Place the baggie in the cup so that the cornstarch mixture is submerged in the iodine water mixture.
4. Record your observations in the data table as the diffusion occurs
5. While you are waiting, answer the questions.

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. At the beginning of the experiment, is the baggie or beaker more concentrated in starch?

2. At the beginning of the experiment, is the baggie or beaker more concentrated in iodine?

Make Some Predictions

1. If the baggie was permeable to starch, which way would the starch move, into the bag or out of the bag? ____out____

2. If the baggie was permeable to iodine, which way would the iodine move, into or out of the bag? ____in___

3. If the baggie was permeable to iodine, what color would you expect the solution in the baggie to turn? __yellow/whitish_____ What about the solution in the beaker? _____whitish yellow______

4. If the baggie was permeable to starch, what color would you expect the solution in the baggie to turn? __white______ What about the solution in the beaker? ____light yellow_____

5. Make a prediction about what you think will happen:

Data Table

Questions:

1. Define diffusion and explain how the process works (what ‘drives’ it?).

Diffusion is the movement of molecules from a high concentration to a lower concentration.

2. Define osmosis

Osmosis is the movement of water molecule from a low concentration to a higher concentration through a semi-permeable membrane. 

3. What is the main difference between osmosis and diffusion

Osmosis moves down the concentration gradient while Diffusion moves from high to love concentration

4. Why is iodine called an indicator?

It is called an indicator because after few minutes of diffusion, it changed the starch from white to a purple like color. The purple color indicates the presence of iodine.

5. Molecules tend to move from areas of __High_____ concentration to areas of __low____ concentration.

Post Lab Analysis

1. Based on your observations, which substance moved, the iodine or the starch?

The iodine moved from the beaker into the plastic in which the starch was in.

2. How did you determine this?

Because the starch changed color while the iodine still remain the same, just a little light in concentration.

3. The plastic baggie was permeable to which substance?

The palastic baggie was permeable to iodine

4. Is the plastic baggie selectively permeable?

Yes it is a selective permeable membrane, because it only allowed certain substance to pass through. In this case it stopped the water molecules in the iodine substance and allowed on the iodine itself to go through it.

5. Sketch the cup and baggie in the space below. Use arrows to illustrate how diffusion occurred in this lab.

6. What would happen if you did an experiment in which the iodine solution was placed in the baggie, and the starch solution was in the beaker? 
Be detailed in your description.

Basically the opposite will happen as we have seen in this lab. The Beaker containing the starch will turn purple while the iodine in the baggie will get lighter in color. 

7. Why is it not a good idea to store iodine in a plastic bag?

It is a bad idea to do so, because iodine is permeable to plastics. So we might see some outflow of iodine from the baggie.

Gabby Rosario

Diffusion Lab

Introduction: In this lab you will observe the diffusion of a substance across a semi-permeable membrane. Iodine is a known indicator for starch. An indicator is a substance that chances color in the presence of the substance it indicates.

 Procedure:

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

2. Fill a beaker halfway with water and add 1ml of iodine.

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

4. Wait fifteen minutes and record your observations in the data table

5. While you are waiting, answer the questions.

Hypotheses:

H0: The iodine will diffuse into the bag.

H1: The iodine will not diffuse into the bag.

Make Some Predictions

1.    If the baggie was permeable to starch, which way would the starch move, into the bag or out of the bag? Out of the bag

2.    If the baggie was permeable to iodine, which way would the iodine move, into or out of the bag? Move into the bag

3.    If the baggie was permeable to iodine, what color would you expect the solution in the baggie to turn? Brown What about the solution in the beaker? Clear

4.    If the baggie was permeable to starch, what color would you expect the solution in the baggie to turn? Clear   What about the solution in the beaker? Light Brown

5.    Make a prediction about what you think will happen:

I think the iodine will enter the bag and change the color of the starch.

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?

Breaker

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

Breaker

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

Baggie

5. Which one is hypotonic in relation to starch, baggie or beaker?

Breaker

                                     Data Table

Post Lab Analysis

1. Based on your observations, which substance moved, the iodine or the starch?

 The iodine moved from the breaker to the baggie.

2. How did you determine this?

I determine this because iodine is a know indicator for starch. An indicator is a substance that chances color in the presence of the substance it indicates.

3. The plastic baggie was permeable to which substance?

The plastic baggie was permeable to the iodine.

4. Is the plastic baggie selectively permeable?

The plastic is a selectively permeable.

5. Sketch the cup and baggie in the space below. Use arrows to illustrate how diffusion occurred in this lab.

6. What would happen if you did an experiment in which the iodine solution was placed in the baggie, and the starch solution was in the beaker? 

Be detailed in your description.

 If we did an experiment in which the iodine solution was placed in the baggie and the starch solution was in the breaker the iodine would move out the baggie. Once the iodine makes it way out the baggie the starch would change color.

1. Why is it not a good idea to store iodine in a plastic bag?

Iodine has the ability to permeate the bag so it’s not a good idea to store it in a plastic bag.