Paper-Wad Diffusion
This activity was sent by Heather Burgess.
Purpose
To help students visualize diffusion of particles and the effect of
temperature on the rate of diffusion.
Background
This activity follows a laboratory experience where the students
observe the effects of temperature on the rate of diffusion of sodium
hydroxide in phenothelein-permeated agar blocks. Students have
been introduced to terms such as diffusion, concentration gradient,
and solute.
Activity
I divide the room into two equal halves using a piece of masking
tape on the floor. The students are told to make 3 paper-wads each
and then to congregate on one side of the room. I tell the students
that their paper-wads are molecules, atoms, particles, etc. and I use
a questioning strategy then to get the students to predict what will
happen if the room was really cold and if they were to throw the
paper wads at each other. The students’ responses are typically that
they would be moving really slow and thus would be throwing the
paper-wads slowly. I then ask them to predict how many paperwads would make it over to the other side of the masking tape. The
students then throw the paper-wads at each other very slowly for a
period of one minute. They are allowed to pick up paper-wads off
the floor as long as they haven’t made their way across the room.
After that time, we count how many paper-wads made it over to the
other side. I then have the students repeat the process, but this
time heating things up. The students predict what will happen and
then pelt each other with the paper-wads very quickly. Again, after
one minute we count how many made it over.
Each time I have done this, we have gotten about three times as
many paper-wads on the other side of the room in the heated
scenario than the cold. The students are able to see the connection
between concentration, temperature, amount of motion due to the
thermal energy, and the rate of diffusion by doing this activity.
Besides, it is great fun for them to throw paper-wads at each other
especially around midterms!
http://www.win.co.nz/bioweb/paperwad.html
Name: ___________________________________ Period: ___ Row: ___ Date: _________________________
Diffusion: Let’s throw some paper!
Introduction: In the last chapter, you were introduced to the cell membrane. Its function is protect the cell and
only allow certain things into and out of the cell. The cell can accomplish this in one of two ways. The first is
passive transport. In this way, the cell does not expend any energy moving materials across the membrane. To
understand this concept you must first understand the following terms: diffusion, osmosis, concentration
gradient, solute, and solvent. In this activity we will be simulating diffusion as a class.
Prediction:
1. Predict how molecules will move when they are cold. How many paper wads do you think will move
across the room when it is VERY cold in here?
2. Predict how molecules will move when they are warm. How many paper wads do you think will move
across the room when it is VERY warm in here?
Materials:
masking tape
colored paper (3 per student)
Procedure:
1. All students with pink paper gather on one side of the room. All students with white paper, gather on
the other side.
2. Wad up your paper into a loose ball. Do not throw the paper until directed by your teacher.
3. Imagine that the room is very cold. Throw the paper as if they are molecules for 10 seconds. When you
run out of paper to throw, pick the paper up off the floor and throw it. Remember to move slowly.
4. Count the number of pink and white papers and record in the data table below.
5. Separate the pink and white papers to either side of the room.
6. Now imagine that the room is very warm. Throw the paper as if they are molecules for 10 seconds.
When you run out of paper to throw, pick the paper up off the floor and throw it. Remember to move
quickly.
7. Count the number of pink and white papers and record in the data table below.
8. Pick up all papers and place them in the recycling bin. Return to your seats and answer the questions.
Data:
Temperature
(approximate)
Left side of the room
Number of pink
Number of
papers
white papers
Right side of the room
Number of pink
Number of
papers
white papers
Cold
Warm
Analysis:
1. How much “mixing” happened in the cold room compared to the warm room? Explain the reason for
the difference.
2. Now imagine that the pink papers represent a bottle of perfume that was dropped on the right side of the
room. When the bottle is dropped, where is the area of highest concentration of perfume molecules?
3. What direction do the perfume molecules move? What direction do the air molecules move?
4. At what room temperature do the molecules “mix” more quickly?
5. Predict what will happen if the simulation were to continue in a warm room. How many pink and white
papers would be on each side of the room?