Student Exploration: Gizmo Diffusion
Name ___________________________________________________________ Block _____
Part 1: Prior Knowledge Question (Do this BEFORE using the
Gizmo.)
1.
What is diffusion?
5. Select the BAR CHART tab (see above), and observe the
chart. After the first 10 seconds or so, how much do the
numbers of particles in each region change?
6. How about after 30 seconds
2. Describe how diffusion allows the smell of freshly popped
popcorn to fill a house.
When the numbers don’t change much, the particles are said
to be in equilibrium.
7. Click Pause (
), and select the GRAPH tab (see above).
What does the graph tell you about the number of
Smells are carried by tiny particles that move through the air.
particles in region A?
The Gizmo shows gas particles in a chamber that is divided
into two regions by a wall. This process, in which particles
move from an area of high concentration (region A) to an
area of low concentration (region B), is called diffusion.
Click Play (
3.
) and observe.
Describe the motion of the gas particles on the screen.
Part 2: Temperature and Diffusion
Get the Gizmo ready:
1. Click Reset (
).
2. Set the Wall
to 100%.
Introduction: In this Gizmo, temperature is measured on the
Kelvin scale. On this scale, 0 K represents absolute zero, the
coldest possible temperature. Water freezes at 273.15 K (0 °C),
4. Over time, what is happening?
and water boils at 373.15 K (100 °C).
Research Question: How does temperature affect the rate of
b) Set the Wall to 50%
diffusion?
c) x in A to 100
d) y in B to 0
1. Observe: Set the temperature (Temp.) to 600 K, and press
Play. Observe the motion of particles. Click Reset. Then set
the temperature to 100 K, click Play, and observe.
e) Temp. to 100 K
f)
Particle mass to 15 amu (atomic mass units).
g) Select the TABLE tab.
h) Press Play. Click Pause when x in A first reaches
2. How does the decreased temperature of the gas relate to the
motion of the particles?
55% or below.
i) Record this Time to reach equilibrium in the tables
in the next column.
5. How did the average time to reach equilibrium compare
between the two temperatures?
The temperature of a gas is a measure of the average kinetic
Temp. = 100K
energy of a set of particles. Kinetic energy (KE) depends on the
Temp. = 600K
how quickly particles move and their mass.
3. Form hypothesis: How do you think an increased
temperature will affect the rate of diffusion? (Use correct
hypothesis format…If….Then….)
4. Set up the experiment by carefully creating the settings listed
below. You will have a chance to make your own experiment
later.
a) Click Reset.
Trial
Time to reach
equilibrium (sec)
Trial
1
1
2
2
3
3
Total
Total
Average
Average
Time to reach
equilibrium (sec)
Hint: The to get the average, add up all the trials and divide the
total by the number of trials (in this case 3).
6. Draw conclusions: Compare the average times to reach
equilibrium for each temperature.
A. How did increased temperature affect the rate of
diffusion?
1. Choose a variable: Pick a variable to investigate: Wall, x in A,
y in B, or particle mass. Which one did you choose?
2. Form hypothesis: How do you think this variable will affect
rates of diffusion? (Use the correct format!)
B. Why do you think this was the case?
7. Extend your thinking: Why do you think the experimental
results were different for each trial in the 100K column?
8. On your own: In our lives, we rarely experience temperatures
like 100K and 600K. They are usually between 373 K (100 °C)
and 273 K (0 °C). Investigate how much diffusion rates differ
between these two temperatures. Describe how the results of
your experiments compare to when you tested the 100K and
600K range.
Part 3: Design Your Own Experiment
Reset the Gizmo before you begin! Introduction: The
Diffusion Gizmo allows you to manipulate five variables: the
Wall, the number of x particles in region A, the number of y
particles in region B, the temperature, and the Particle mass.
3. Set up experiment: In a controlled experiment, only one
variable is manipulated, or changed. It must be one of the
first four in the list below. Set up your experiment so that
there are just one difference between set-up A and set-up
B.
4. Copy the Gizmo settings you will use for each set-up below
directly from your screen.
Set Up A
Set Up B
Wall
Wall
X in A
X in A
Y in B
Y in B
Particle Mass
Particle Mass
Temp.
Temp.
5. Gather data: Use the Gizmo to fill in each table. As before,
the “time to reach equilibrium” is the time it takes for the
number of x particles in region A to reach 55% or lower.
Trial #
Set Up A
Time to Reach Equillibrium
(sec)
6. Draw conclusions: Compare the average times to reach
equilibrium for each set-up.
A. How did the variable you investigated affect the rate
of diffusion?
1
2
3
B. Why do you think this was the case?
Total
Average
Trial #
Set Up B
Time to Reach Equillibrium
(sec)
1
2
3
Total
Average
Hint: The to get the average, add up all the trials and divide the
total by the number of trials (in this case 3).
7. Take the quiz at the end of the gizmo. Your scores will be
recorded automatically.