Diffusion Lab Write-up
Question:
How does temperature of water affect the diffusion rate of potassium
permanganate through the water?
Hypothesis:
If the temperature of the water is high, then the particles will diffuse faster, and if
the temperature of the water is low, then the particles will take longer to diffuse,
because heat is energy, and energy causes particles to move faster, thus
spreading out faster.
Materials:
-potassium permanganate
-petri dishes
-stopwatches
-camera
-water (hot and cold)
Variables:
-manipulated: temperature of water (hot or cold)
-controlled: amount of water
-controlled: amount of potassium permanganate
Method:
To answer the question posed, we will see how fast potassium permanganate
spread out in hot water and in cold water.
Procedure:
Fill a petri dish with 60 mL of cold water.
Pour in a controlled amount of potassium permanganate and start the watch.
Once the deep purple has fully reached the edges, stop the stopwatch.
Record the time in a table.
Clean and dry the petri dish.
Repeat steps 1-5 twice.
Repeat steps 1-6 with 60 mL of hot water instead of cold water.
Data Table:
Temperature (˚C)
7
10
12
54
57
60
Graph:
Rate of Diffusion
(seconds)
273
262
253
188
184
143
Conclusion:
The data collected supports my hypothesis that the potassium permanganate would
diffuse faster in hot water than in cold. The line graph shows that the higher the
temperature, the less amount of time it took for the substance to diffuse. Thus, the
higher the temperature is, the higher the rate of diffusion will be, and vice versa.
Evaluation:
This lab was sufficient enough to gather data to answer the question posed, but I still
feel like a few things could be changed to make the lab better. For example, we could
have determined a more exact indicator for when to stop the timer. We considered the
potassium permanganate “diffused” when the deep purple had fully reached the edges
of the petri dish. This method is not completely accurate, as the naked eye is not the
best observer. With the potassium permanganate itself, each time, the powder was
poured into the water at a different rate and with different effort behind it, and there were
different amounts. This could cause the potassium to spread faster or slower depending
on how much and quickly the substance filled the water.
JOURNAL ENTRY:
Filling petri dishes with water and then pouring purple stuff into them? This is the life. It
was a simple and stress-free lab; bordering on nothing compared to previous labs I’ve
done. Relaxing, yet simple and effective, and related to what we are learning so we can
make real-world connections and gain a deeper understanding of cells.
This lab relates to the cell because diffusion does not require energy from the cell, and is
essential for a cell’s functions. Naturally, substances and particles move from areas of
high concentration to areas of low concentration. When a cell is low on proteins, there is
a low concentration of proteins in the cell. Particles move from outside the cell (high
concentration), through the semipermeable membrane, and into the cell. Through
diffusion, cells are able to excrete waste and unwanted material from the inside, and get
important substances from the outside.