Diffusion Rate

1

• Diffusion Rate
• CHEMICAL DIFFUSION IN AGAR

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Click here to print a Data Table you will need
for this experiment
2
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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3
This exercise investigates diffusion as it
applies to movement of particles in a semi-solid
material called agar
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4
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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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
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Chemical Diffusion in Agar
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SIZE OF THE MOLECULES Smaller molecules move
faster than larger molecules
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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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Chemical Diffusion in Agar
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for this experiment
10

• Procedure
• Obtain two test tubes with agarYou can obtain
  the test tubes by clicking on the test tube rack
  on the shelf to the left

Test tube rack
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Procedure 2) Mark the test tubes as1 and 2If
you click on the pencil lying on the shelf to the
left you can mark the tubes
1
2
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Procedure 3) Add a small amount of methylene blue
to test tube 1You can click on the blue
eyedropper lying on the shelf to the left to add
the dye
1
2
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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 agarYou can measure the progress of
the dye by observing the mm marks on the test
tubes
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this experiment again
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2
START
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Procedure 5) Add a small amount of potassium
permanganate to test tube 2You can click on
the green eyedropper lying on the shelf to the
left to add the dye
1
2
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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 agarYou can measure the progress of the dye
by observing the mm marks on the test tubes
Click here if you messed up and would like to try
this experiment again
1
2
START
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DATA 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
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Table
Data Table for Diffusion of Different Molecular Weights Data Table for Diffusion of Different Molecular Weights Data Table for Diffusion of Different Molecular Weights Data Table for Diffusion of Different Molecular Weights Data Table for Diffusion of Different Molecular Weights
Methylene blue (molecular weight of 320) Methylene blue (molecular weight of 320) Methylene blue (molecular weight of 320) Methylene blue (molecular weight of 320) Methylene blue (molecular weight of 320)
Time 15 min 30 min 45 min 60 min
Distance
Potassium permanganate (molecular weight of 158) Potassium permanganate (molecular weight of 158) Potassium permanganate (molecular weight of 158) Potassium permanganate (molecular weight of 158) Potassium permanganate (molecular weight of 158)
Time 15 min 30 min 45 min 60 min
Distance
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Questions 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?

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At this point you have finished experiment 1 for
this lab Would you like to end your session or
continue to the next experiment?
End this Session
Continue to Experiment 2 (PASSIVE MOVEMENT)
Continue to Experiment 3 (OSMOSIS AND DIALYSIS)
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Data Table for Diffusion of Different Molecular Weights Data Table for Diffusion of Different Molecular Weights Data Table for Diffusion of Different Molecular Weights Data Table for Diffusion of Different Molecular Weights Data Table for Diffusion of Different Molecular Weights
Methylene blue (molecular weight of 320) Methylene blue (molecular weight of 320) Methylene blue (molecular weight of 320) Methylene blue (molecular weight of 320) Methylene blue (molecular weight of 320)
Time 15 min 30 min 45 min 60 min
Distance in mm
Potassium permanganate (molecular weight of 158) Potassium permanganate (molecular weight of 158) Potassium permanganate (molecular weight of 158) Potassium permanganate (molecular weight of 158) Potassium permanganate (molecular weight of 158)
Time 15 min 30 min 45 min 60 min
Distance in mm
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Data Table if you are Online
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