1) Diffusion Rate

CHEMICAL DIFFUSION IN AGAR

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Experiment #1 Click here to print a Data Table you will need for

this experiment

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Diffusion is a process of equalization which involves movement of molecules from an area of high concentration to an area of low concentration

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This exercise investigates diffusion as it applies to movement of particles in a semi-solid material called agar

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Molecules are in a constant state of motion

The motion of these molecules are influenced by many factors

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FACTORS INFLUENCING DIFFUSION

1) Kinetic Energy2) Nature of the environment3) Size of the molecules

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KINETIC ENERGY

The driving force which causes

the molecules to move

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Diffusion in Agar

NATURE OF THE ENVIRONMENT

The agar environment we will be

using is a semisolid material

through which we will measure the

rate of diffusion of substances with

different molecular size

SIZE OF THE MOLECULES

Smaller molecules move faster

than larger molecules

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Diffusion in Agar

LAB REPORTYou will need to supply the following in your lab report for this experiment #1

1) Data Table for Diffusion of Different Molecular Weights

2) Answers to questions 1-4

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this experiment

Procedure

1) Obtain two test tubes with agar*You can obtain the test tubes by clicking on the test tube rack on the shelf to the left

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Test tube rack

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Procedure

2) Mark the test tubes as#1 and #2*If you click on the pencil lying on the shelf to the left you can mark the tubes

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Procedure

3) Add a small amount of methylene blue to test tube #1*You can click on the blue eyedropper lying on the shelf to the left to add the dye

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Procedure

4) Quickly click on the START button on the timer and record on your printed Data Sheet every 15 minutes the distance the dye has moved through the agar*You can measure the progress of the dye by observing the mm marks on the test tubes

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up and would like to try this

experiment again

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Procedure

5) Add a small amount of potassium permanganate to test tube #2*You can click on the green eyedropper lying on the shelf to the left to add the dye

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Procedure

6) Quickly click on the START button on the timer placed on the table and record every 15 minutes the distance the dye has moved through the agar*You can measure the progress of the dye by observing the mm marks on the test tubes

11 22START

00:00

05:00

10:00

15:00

20:00

25:00

30:00

35:00

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60:00

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up and would like to try this

experiment again

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Click the Play button to view the diffusion of dye in an agar plate. Which

chemical would you propose is

smaller the RED or BLUE?

DIFFUSION OF DYE IN AGAR

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DATADATA

At this point you should have collected diffusion distance data for methylene blue and potassium permanganate

Include your data tables with your lab report when you are finished

Data Table for Diffusion of Different Molecular Weights

Methylene blue (molecular weight of 320)

Time 15 min 30 min 45 min 60 min

Distance

Potassium permanganate (molecular weight of 158)

Time 15 min 30 min 45 min 60 min

Distance

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QuestionsQuestions

Answer the questions (1-4) for this experiment

Hand your answers in with your lab report

1) What are the three things which influence the movement of molecules (and particles)?

2) In agar, what size of molecules move the fastest?

3) Which dye, the methylene blue or the potassium permanganate, diffused at the fastest rate?

4) Why did one dye diffuse faster than the other?

At this point you have At this point you have finished experiment #1 for finished experiment #1 for this labthis lab

Would you like to end your Would you like to end your session or continue to the session or continue to the next experiment?next experiment?

Continue to Experiment #2 (PASSIVE MOVEMENT)

Continue to Experiment #3 (OSMOSIS AND DIALYSIS)

End this Session

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Data Table for Diffusion of Different Molecular Weights

Methylene blue (molecular weight of 320)

Time 15 min 30 min 45 min 60 min

Distance in mm

Potassium permanganate (molecular weight of 158)

Time 15 min 30 min 45 min 60 min

Distance in mm

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Table if you are Online