Rebel Science – Elephant Toothpaste
name:
Any of the red, italicized words must be
included/modified in you final report
Introduction/Background Section ( ¾ page)
This experiment shows the decomposition of hydrogen peroxide catalyzed by potassium iodide(with
a chemical formula of___________). Define a catalyst:_________________________________
______________________________________________________________________________
Must Add:
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what a supersaturated solution is
the variables we are changing and why
more background with dates and locations of first
how we will know if we succeeded
a solid, clear hypothesis
include the safety concerns
must put these
in the right order
The rapid catalyzed decomposition of hydrogen peroxide produces O2
gas which forms a foam with the liquid detergent:
2H2O2 (aq) + KI (aq)

2H2O + O2 (g) + I2
The I-1ion is a catalyst for the reaction. The brown color of the foam is evidence of iodine in the
reaction. It will stain clothes, skin, and carpet.
Provide a Clear set of variables using the headings:
Controlled
Independent
Dependant
Materials: You will need to add the correct items(and the number of each) that we used for the
modified set up (1/2 page)
250 mL and 25 mL graduated cylinder
food coloring
Dish detergent
30% hydrogen peroxide (H202)
saturated solution of potassium iodide (KI)
disposable gloves
Rebel Science – Elephant Toothpaste
name:
Hazards:
1. Wear safety goggles. Also, wear disposable gloves when pouring 30% hydrogen peroxide, as it
is a very strong oxidant. Define this term.
2. Wear an apron – they are located next to the fume hood on your right side of the class.
3. Do not stand over the graduated cylinder because steam and oxygen are produced quickly.
4. Use extreme caution when handling the H2O2 solution – it will burn you!!!
Procedure:
You must decide where to add in the correct steps here (1/2 to ¾ page):
1. Using a 250 mL graduated cylinder obtain 40 mL of 30% H2O2 from the instructor at the front
bench.
2. Put the cylinder into the sink on your bench (remove black cover) and add 20 mL of dish soap and
swirl it to mix.
HINT : how can you tell you have added the correct amount?______________________
3. Next measure out 15 mL of the KI solution located on the front bench and return it to your
workstation.
4. Obtain a disposable dropper and fill it with your choice of food colouring and return to you
workstation.
5. Tilt the 250 mL graduated cylinder in the sink and drip food coloring down the sides of the
graduated cylinder to make your toothpaste striped/swirled/whatever – you can share if you like to make
it multicoloured.
6. Quickly add the saturated solution of KI solution and stand back - Be sure to move your hand away
from the top of the graduated cylinder quickly or the hot foam will get on your hand and arm.
Observations (1/2 page) Include a table with your qualitative observations and quantitative
measurements. Make sure it simple, clear and has a descriptive title.
Conclusion and Evaluation (3/4 page max)
In this section you accept or reject your
hypothesis and give a justification for this. You also must
suggest some improvements to your procedure for someone
else to follow should they choose to try and repeat your
experiment.
Rebel Science – Elephant Toothpaste
name:
Here is how you will be marked:
Intro (13)
Clearly states the Aim of experiment
=1
Explains the background of the experiment = 4
States date/time/locations
=2
Hypothesis in form of If / Then statement = 2
Clearly identifies
1. Controlled variables
=4
2. independent variables
=1
3. dependant variable
=1
Materials(5)
Includes all necessary equipment/materials = 4
Missing 1-3 pieces of equipment
=3
Missing 4-6 pieces of equipment
=2
Missing 7 or more pieces
=1
Methods(10)
Missing no steps and they are clearly articulated
= 10
Missing only 1to 2 or up to 3 unclear statements
=9
Missing 3 to 6 steps and 4-7 unclear
=8
Missing 6 to 10 steps and 7 or more unclear steps
=7
Missing more than 10 steps and more than 8 unclear steps = 5
Results(8)
Clear observations table with clear title, units and uncertainties given
Conclusion(12)
Clearly accepts or rejects hypothesis with a justification
Lists 5 or more problems with the procedure
Suggests realistic improvements for each of the problems listed
=3
=2
=5
=5
Total = 50 marks
/ 30