Pre-AP Chemistry
Instructor: Mr. Malasky
Name ___________________________________ Period _________ Due Date _____________
Laboratory Activity: Energy of Oxidation
Background
The smoke bomb you would purchase from a fireworks store usually is made from potassium
chlorate (KClO3 - oxidizer), sugar (sucrose - fuel), sodium bicarbonate (baking soda - to moderate the
rate of the reaction and keep it from getting too hot), and a powdered organic dye (for colored smoke).
When a commercial smoke bomb is burned, the reaction makes white smoke and the heat evaporates
the organic dye. Commercial smoke bombs have small holes through which the smoke and dye are
ejected, to create a jet of finely dispersed particles. Crafting this type of smoke bomb is beyond most of
us, but you can make an effective smoke bomb quite easily. Potassium nitrate will serve as the oxidizer
for your smoke bomb.
The choice of an oxidizer is always an important part of designing a reaction where a fuel is
expected to be consumed. When heated, potassium chlorate will decompose and produce an abundance
of oxygen. The oxygen in the presence of a fuel, like sugar, will ignite the sugar and produce a highly
exothermic reaction that can continue the oxidation of the sugar at a rapid rate of combustion. The vast
amount of energy from the oxidation of a carbohydrate (gummy bear) can easily be demonstrated.
Materials
KNO3
KClO3
sucrose
Al foil
hot plate
250 ml beaker
lighter/matches
stirring rod
tongs
ringstand
utility clamp
balance
large test tube
gummy bear
burner
weigh boats
Methods- Smoke Bomb
1. Combine 10.0 grams of KNO3 and 6.9 grams of sucrose in a 250 ml beaker. (An alternative is 10.0 g
of KClO3, 6.9 g of sucrose, and 1.0 g of NaHCO3)
2. Gently and carefully heat on a hot plate with continual stirring until the sugar just begins to
caramelize and the mixture is a semi-solid. DO NOT stir in a fashion that allows any of the mixture
to fall on the hotplate!!! Note properties of the mixture.
3. Remove from the heat and transfer into a pile (while shaping) on a piece of Al foil, making sure an
extended surface will serve as an ignition point. Immediately clean the beaker.
4. Allow the mixture to cool on the foil.
5. OUTSIDE- Pull back the foil put a small amount of lighter fluid on the foil, then ignite. Note
observations of the burning process.
Gummy Bear
6. Measure 5.0 grams of potassium chlorate and place in a large test tube. Clamp this tube to a
ringstand and heat with the burner until the chlorate appears molten; it will bubble with oxygen
being released.
7. UNDER THE FUME HOOD- Drop a gummy bear into the tube and observe. Note observations
related to the reaction. Once cooled, rinse the tube to remove as much solid material as possible,
then place the tube in a location designated by instructor.
-----over
Observations (60 pts)
1. smoke bomb mixture-
2. burning of smoke bomb-
3. oxidation of gummy bear-
Questions (40 pts)
1. Suggest a way that a smoke bomb is similar to gunpowder, and a way that it is different. (research if
necessary!)
similardifferent-
2. Why would any candy serve as a good oxidation substance in hot potassium chlorate?
3. Why would an oxidizer (like KNO3) also be called an oxidizing agent?
4. Why do these oxidation reactions essentially represent combustion reactions?
5. Potassium chlorate decomposes to produce potassium chloride, while potassium nitrate gives
potassium nitrite. Based on this information why would it be safer to use potassium nitrate? Hint:
balanced decomposition reactions.