1. Luke Wang
October 27, 2009
Mr. Ferguson
Biology 9 3B
Diffusion Lab Report
Question
How will the temperature of the water affect the rate of diffusion?
Hypothesis
If the water temperature is higher, then the rate of diffusion will increase, and
vice versa.
Variables
Independent Variable
Water Temperature
Dependent Variable
Rate of Diffusion
Controlled Variables
Amount of water
The variation of the amount of water put in to the petri dish can
also affect the rate of diffusion, so it must stayed the same for
all tests.
Amount of Potassium Permanganate
Adding different amount of potassium permanganate to the
water can affect the rate of diffusion, so same amount of
potassium permanganate should be added to the water every
time.

2. Materials
• Three petri dishes
• Potassium Permanganate
• Hot, Normal, Cold water
• Two Stopwatches
• One Thermometer
• One Camera
Procedure
1. Get a petri dish
2. Pour hot water into the petri disk until full
3. Put a small amount of potassium permanganate
4. Start the stopwatch immediately after putting the potassium permanganate
5. Wait until the dark purple fills the bottom of the petri dish
6. Stop the stopwatch
7. Record the data
8. Repeat steps 1-7 for normal and cold water

3. Table
Amount of Time It Took for
Diffusion To Complete In Three
Different Water Temperatures
Trial 1 Trial 2
(Seconds) (Seconds)
Hot Water 186 121
Normal Water 600 377
Cold Water 743 646
Graph
Rate of Diffusion
800 743
700
600
600 646
500
400
377
300
186
200
100
121
0
Hot Water Normal Water Cold Water
Trial 1 (Seconds) Trial 2 (Seconds)

4. Analysis
The graph shows that when water is hot, the rate of diffusion is much faster even
when comparing to normal temperature water. On the first trial the diffusion process
finished in 186 seconds, but it took 10 minutes in normal water, and 743 seconds in
cold water. The diffusion process took the longest in cold water, since it got the
lowest water temperature which was only about 5 degrees Celsius. The diffusion
process in hot water was almost 3.3 times faster then diffusion in normal
temperature water. The such big difference can be explained by the great difference
in water temperature. The hot water I used for this experiment was about 70.5
degrees Celsius, but the normal water was only about 19 degrees Celsius. The time
difference between diffusion in normal water and cold water was still obvious, even
though the temperature difference was not as great hot water to normal water. It took
cold water about 1.2 times longer for the diffusion process to complete in the first
trial, and about 1.7 in the seconds trial.
Conclusion
After doing this lab, I had a better idea on how the temperature can affect the rate of
diffusion greatly. Also my hypothesis had been proven to be correct, when the
temperature is higher, the rate of diffusion did increase. Although we had discuss
about the factors that will change the rate of diffusion, but this lab create a better
image in my mind how the rate of diffusion changed when the temperature rises.
Evaluation
Although the data I collected during this experiment had shown higher temperature
will increase the rate of diffusion. However the great different between the first trial
and the second trial was very strange. The diffusion process took about 10 minutes
in normal water in the first trial, but it only took about 377 seconds in the second trial.
Things that could have cause that problem were how we determined the diffusion
process is complete. We decided that when the bottom of the petri dish is completely
coated with a purple color, that is when diffusion is complete. When we did the petri
dish with the hot water, we put the petri dish on a dark surface, so the color of the
water appeared to be darker, and we used that as our reference. However for the
normal water and cold water, we put the petri dish on a white paper to take better
pictures, which caused the water appear to be lighter. Therefore, we couldnʼt get the
same color as the one we got when we put the petri dish on a dark surface. Next
time I should have a consistent environment for testing, so the result will be kept
accurate.

5. Luke Wang
October 27, 2009
Mr. Ferguson
Biology 9 3B
Journal
How Is This Lab Related to the Cell
This lab was generally about how
temperature affects the rate of diffusion.
Since diffusion is very important to cells, so
this lab helped us understand how diffusion
will occur in a high temperature environment.
We used potassium permanganate and water
to simulate what will happen in cells. When
potassium permanganate was not put in the
water, the water had a low concentration of it.
After we put potassium permanganate in the
water, the potassium permanganate was a
high concentration area. By diffusion the
potassium permanganate will spread out in the water so the level of potassium permanganate
would be about the same level. When cells is lack of something, it has a low concentration of
that thing, by diffusion the area that has this thing will start to move in to the cell, until the
level of that thing is balanced. When temperature was increased in this lab, the whole process
took less time to complete, since the particles were moving faster in the water. In cells, when
they are in a hotter environment, the
particles will move faster in and out of the
cells, which will make the process of
diffusion faster. On the other hand, when
the temperature of the water in our lab was
decreased, the diffusion process took a lot
longer to complete, since the particles
were moving lot slower. This is the same
when cells are in a colder environment,
the particles will not move as faster as
they would in hot environment. Therefore,
the particles will move in and out of the
cells lot slower.