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Background Information
The purpose of this activity is to give
you practice conducting experiments and writing lab reports. As
you work on this activity, think about what you are testing, how
you are controlling the experiment, and how it relates to weathering.
In order to discover factors that affect chemical
weathering of rocks, your mission is to dissolve an alka-seltzer
tablet as quickly as possible.
Watch the video of me modeling the blowing a
lid off a film canister using a whole alka seltzer tablet and plain,
room temperature and water. Time how long it takes between putting
the lid on the container and when it flips.
Materials
Alka seltzer tablet(s) - (only one is required, but who can resist
blowing the lid off several times!)
Water
1 film canister (you can usually get these from a film developing
store)
stop watch
optional: vinegar (acid) baking soda (base), hammer, or other
Hypothesis:
Your first step is to write a hypothesis. As we've discussed earlier
in this course, a good hypothesis contains two parts: background
information and a prediction. Background information can include
information you already know about a subject, information you read
and research, observations you have made during previous activities
and during your lifetime. Remember, the experiment we are doing
now is to model weathering of rocks, therefore your background information
should somehow relate to weathering. The second part of your hypothesis
is a prediction. This should include a specific prediction of what
will happen and why. If I xxx, then yyy, because zzz.
Look in Earth Science or Geology textbooks or
check out the following websites to conduct research about chemical
and physical weathering processes. Think about how the alka seltzer
experiment relates to what you read.
USGS:
Geologic Glossary
Utah
State Office of Education: Weathering of Rocks and Minerals
University
of Portsmouth: Gravestone Weathering
Procedure:
Once you have made a prediction, you should think of a procedure
that will help you test that prediction. Your procedure should be
in step-by-step format. Explain exactly what you will do so that
someone else could follow your experiment exactly.
Remember, an experiment should have only one
variable, or thing that is changed from one trial to the next. Think
about what you are going to do. Is it exactly the same as what I
did except for one change? If you have more than one variable then
it is hard to interpret your results.
Data:
Your data will depend on your procedure but should include the time
it took you to blow the lid of your film canister. If you have much
data, be sure that it is organized in a clear way.
Conclusion:
Write a conclusion that has three parts. One part should specifically
explain what happened. The next part should explain why you think
that happened. You should relate this information back to what you
discussed in the background information part of your hypothesis.
Finally, you should include some limitations ('If I could do it
differently'… 'In the real world'… etc.) and sources of
error.
Assessment:
Once you have conducted the experiment and written the entire lab
report, click the link below to submit it to me for grading. It
will probably be from one to two typed pages. The lab report will
be scored using the science-inquiry scoring-guide based on the state
CIM standards.
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