Name: _______________________________________
Variables – Lab Review
Answer the following questions based on yesterday’s lab and your
understanding about variables. You should use your notebooks with your notes
and lab notes to aid you.
1. What was the Independent Variable being investigated?
IV: Temperature (evidenced by hot water, heating test tubes)
2. What was the Dependent Variable being solved?
DV: Reaction rate/speed (evidences by “racing” and mixing same time)
3. Identify as many controlled variables as you can from this experiment:

10 drops chem A in both A test tubes

10 drops chem B in both B test tubes

1 set test tubes (A&B) put into hot water same time
 1 set test tubes (A&B) placed in test tube rack/room temp
 Mixed both sets chemicals at same time
4. This experiment is known as a Controlled Experiment. Why is it
considered this?
Two sets of identical chemicals mixed with same results at same time but
only one change made; IV
5. How was the independent variable tested? Explain.
One set of test tubes put into hot water to warm temp; other set of test
tubes left at room temp; both sets mixed same time and results compared
by looking for which set reacted first.
6. There were two sets of chemicals tested. Write the formulas for the two sets
(be careful, not two chemicals, two sets):

KMnO4
And
KI

K2S2O8
And
H2C2O4
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Name: _______________________________________
7. How did the two different set of chemicals differ? List any observable
differences before and after the test.
 Before – one set both liquid, one colorless, one purple; second set both
liquid, both colorless
 After – both sets turned yellow liquid
The following questions are about only the one set of chemicals your group
tested:
8. You did two tests. Which test was the “normal” experiment?
The chemicals at room temp
9. Why is this set considered the “normal” experiment?
No changes were made to vary experiment
10.How did you make sure that there were no other factors that would
influence this test?
Exact measurements of drops, size and number were placed in each test
tube; chemicals were mixed at same time by stating “ready, set, go” with
partner; same type droppers/pipets were used
11. What factors could have changed your final results if your group wasn’t
careful (error – human error is not an answer)?
Too big or small of drops; miss counting drops; water left in test tube; not
mixing exactly at same time; holding “normal” set causing them to warm
up, etc.
12. How did you know when the experiment was “finished” or reacted?
Known color change of yellow was achieved
13. You completed two tests with same chemicals. Did both sets of chemicals
react the same way?
Yes, because it was the exact same chemical with only a temp change
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Name: _______________________________________
14. Why is this important (number #13)?
In conducting an experiment, only one variable can be tested at a time
which was temp
15. How did the second test differ from the first test?
For the second set of chemicals we changed only the temp of the chemicals,
everything else was the same
16. What parts of the second test remained the same as the first test?
Number of drops of each chemical, time waited to mix, mixing at same
time, etc.
17. Why is this important (number #16)?
When conducting controlled experiment only one factor can be tested at a
time or the results will change/be flawed
18.How did you know if the “changed” variable affected the reaction of the
chemicals?
By comparing the results of the “normal” set or controlled set of chemicals
19.In the end, the results of this experiment was (evidence of change)…
The observation of yellow color change, which occurred in the hot
chemicals first, shows that heating the chemicals speeds up the reaction
20. In making the statement in #19, could you say this statement is the
same for the other set of chemicals the other group tested? (more than a
yes/no answer- explain)
For the chemical test by the other group, their results showed also that
heating the chemicals speeds up the reaction
21. Make an inference regarding your final results using the data collected
from both your group’s experiment and the other groups’ experiments.
Heating up chemicals will cause them to react faster when mixed together
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Name: _______________________________________
22. Write a Theory for this experiment (look the definition up if you are
unsure).
(Theory is explaining why something happens) When heating chemicals,
this causes the chemicals to react faster because the particles that make
them up collide faster (work)
23. Write a Law for this experiment (look the definition up if you are
unsure).
(Law description of how something happens) When heating any
substances/chemical before mixing them, will cause their reactions to
occur faster
24. What is the difference in these two statements.
A Theory is an explanation of why something happens where a Law
describes what is happening
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