Name ____________________________________
Date _________________
LAB 1.3
The Most Absorbent Paper Towel
You are being given fairly detailed instructions on how to design your own labs—instructions
will be given to you stating exactly what goes in each section of a lab report. As you progress
through the book, less information will be given as you become more accustomed to designing
your own labs.
Purpose To determine which paper towel is most absorbent for its price
Possible materials water, various paper towel samples, graduated cylinder, beakers, balance,
ruler
Safety No chemicals other than water are being used, and there is no heating of any chemicals.
Use caution with glassware.
Instructions You need to further define your purpose/problem. You know you’re going to
compare differently priced paper towels, but how will you define “absorbent”—by mass of water
absorbed or by volume? (Don’t write this down now, just decide—you’ll write it in a minute.)
Begin writing your lab report:
• Restate the purpose/problem. Remember to clearly state your variables in the
purpose/problem—don’t use the generic statement above.
• Write background information—what information do you already know about your
variables and how paper towels absorb water?
• Next, write a hypothesis. Which sample do you believe will perform best based on your
variables? Remember to write a hypothesis and not a prediction!
Copyright © 2009 by Kendall Hunt Publishing Company
Page 1 of 5
• List your variables (specify dependent and independent) and as many constants as you can.
Although the next sections typically appear in the order “materials, safety, procedure, data table,
calculations,” it is often most effective to write them in the order “calculations, data table,
procedure, materials, safety.”
• For the calculations/results, you will need to compare your dependent and independent
variables in some way. For this lab, the most appropriate way is to find a ratio of dependent
to independent measurement (amount of water absorbed/price of paper towel). Be sure to
specify how you’re going to measure “amount of water”—either “mass of water” or “volume
of water.” You’ll also need to average multiple trials for each paper towel. Set these
calculations up (you’ll plug in the numbers after performing the experiment, but get them set
up first).
• Once you determine what you need for your calculations, you can then determine what you
need to put in your data table. Make sure everything needed in your calculations is included
in your data table. You will need to take into account how you plan to measure the water:
volumes are measured in graduated cylinders, and masses on balances. Keep in mind when
making your data table and procedure that you should not put wet paper towels directly on
the balance—if you want to find the mass of a wet paper towel, you will have to put it in a
beaker to use the balance, so then you would also have to know the mass of the empty beaker
to find the mass of the paper towel. This type of calculation (finding the mass of the wet
paper towel from subtraction) would also need to be added to your calculations section that
you made above—not in the data table.
Copyright © 2009 by Kendall Hunt Publishing Company
Page 2 of 5
• Next, write the procedure. For each quantity that you need to measure in the data table,
write a procedure step to either set it up or to measure it. Include steps specifying how you
will know when to stop adding water to the paper towel. There are many ways to do this—
just pick one and be consistent. Use clear, concise language, and number your steps. Include
three trials of each type of paper towel.
• From your procedure, make a detailed materials list. Write down each item you need in
your procedure, and exactly how much you need of it. The only exception to this is water—
you have access to an unlimited supply of water in most situations, and therefore you do not
need to write down the amount you will use in the materials list. A list of possible materials
is provided above. You may not need all the materials listed, and you may think of
something not on the list. If you do, be sure to ask your instructor before you finalize your
plans to make sure that it will be available for you.
Copyright © 2009 by Kendall Hunt Publishing Company
Page 3 of 5
Safety
• Go through the materials list and write down any safety concerns about materials. Your
instructor will probably give you safety information about any chemicals that you are using. You
should also consider the safety of using glass (especially hot glass), hot plates, burners, open
flames near flammable chemicals, and anything else you see in your procedure that could cause a
problem. You should always use goggles if you are using any chemical other than water and if
you are heating any chemical (including water). Only after your lab is planned and written up,
perform your experiment. If you need to make adjustments to any section of your report, do so in
writing. For example, if you realize you forgot a step in the procedure, write it in as you do it.
When you are finished with the experiment, the report should accurately state exactly what you
did.
• Complete your calculations/results section by performing the calculations you set up earlier. You
should show each of the equations for these calculations, as well as the numbers plugged into the
equation for the first trial. For the second and third trials, you may just write the answer to the
calculations; it is assumed that you did it the same way as the first trial. After your calculations,
write a general statement of any trends or patterns in your results (such as “X brand absorbed a
higher volume of water per mass of paper towel than Y brand”). Do not attempt to explain why
you got these results, just state them in sentence form.
Copyright © 2009 by Kendall Hunt Publishing Company
Page 4 of 5
• Write your conclusion. It should restate the purpose/problem and completely answer it. Was
your original hypothesis supported or not? Explain why you think you got these results based on
the chemistry you understand up to this point. Give at least two possible sources of error
(remember, “human error” is too broad, and “calculations” won’t count). “Possible sources of
error” does not mean that you did things wrong, but points to places in the lab where error could
occur in data gathering to throw off the results. Also write one additional investigation or one
question that you now wonder about.
• Compare your results and conclusions as a class. Do this on whiteboards if your teacher
provides them. Discuss as a class the different ways that were used to determine when to stop
adding water. Include your answers to these questions in your conclusion as well.
• What are the pros and cons of these different methods?
• Did the different methods give similar or different results for the most absorbent
paper towel for the price? Explain why.
Copyright © 2009 by Kendall Hunt Publishing Company
Page 5 of 5