Hands-On Activity
A Chemical Reaction
Materials
• For each student:
o Pair of goggles
o Laboratory Apron
o Gloves
• Each group of students:
o 250 mL beaker
o Balance
o Copper(II) chloride dihydrate (cupric chloride, CuCl2•2H2O) crystals (1 small container for every
two groups)
o Piece of heavy aluminum foil (approx. 5 cm x 5 cm) or 1 piece cut from an aluminum pie pan
o Thermometer
o Stirring rod
o Test tubes
o Graduated cylinder
o 100 mL of tap water
o Paper towels
o science journal or notebook
• For Entire Class Demonstration”
o Potassium chlorate (10 g)
o Gummy Bear
o Match
o Wood Splint
o Rind stand
o Clamp
o Pyrex or other heat-resistant test tube
o Bunsen Burner
Demonstration
Caution: When the reaction proceeds with the addition of the gummy bear, there is a flame and great
deal of heat that is created. The open end of the test tube should never be pointed at anyone. It is
suggested that a fire extinguisher, and fire blanket be present at all times and students know the
location and proper use of each. Make certain that students know the location and proper use of the
eyewash station.
This demonstration shows three indicators of a chemical reaction; production of a gas, production of
new substances, production of heat/light, and color change. Point these out to students as you move
through the demonstration. Students are asked to observe the demonstration and record their
observation in their science notebooks. Then they interpret their observations as evidence that a
chemical reaction has occurred.
1. Place about 10 g of potassium chlorate in a Pyrex or other heat-resistant test tube.
2. Secure the test tube to the ring stand with a test tube clamp. Clamp the test tube firmly at a 45°
angle and be very sure the open end is not pointed at the class or yourself.
3. Light the Bunsen burner and heat the test tube to melt the potassium chlorate crystals. (As the
crystals melt, bubbles can be seen inside the test tube. Potassium chlorate is decomposing to
form potassium chloride-liquid, and oxygen gas which has created the bubbles)
4. Light the wood splint, blow it out, and while it is still glowing hold the glowing end just inside the
mouth of the test tube. The splint will burst into flame indicating the presence of oxygen gas.
Remove the splint. Describe to students what this test shows.
5. Place the gummy bear in the test tube.
6. The reaction will occur and a colorful flame will appear out of the test tube. (production of
heat/light)
7. When the reaction ceases, point out the charred remains in the test tube, but do not touch the
test tube- it will be extremely hot! (color change) Point out to students that the reaction is
caused the sugar (sucrose) in the gummy bear reacting with pure oxygen as it is released by
the molten potassium chlorate.
8. Tell students that the main products of the reaction are carbon dioxide, CO2, and water vapor,
H2O. Both are gases and are ejected from the mouth of the test tube.
Student Activity
Caution: Students should know the location and proper use of the eye wash station in case chemicals
enter the eye.
Before students begin the activity, review the proper use of the lab equipment.
Balance: Be sure students know how to measure mass by differences, using an empty container or a
clean piece of paper. Students should never place substances directly on the balance pan.
Graduated cylinder: Have students practice measuring volumes of liquids, reading the bottom of the
meniscus at eye level.
Thermometer: Students should understand that laboratory thermometers must be read while
immersed in the material whose temperature is to be recorded. They should not withdraw the
thermometer and hold it up to the eye.
Test tubes: Show students how to handle test tube using a spring-loaded test tube holder. Also caution
students that the mouth of the tube should never be pointed at another person.
Inform students that they are about to create a chemical reaction. Caution them that they must wear
goggles, aprons and gloves while doing this activity and that they should handle the chemical that you
are about to provide them with care, avoiding spills and contact with their skin. Remind them that they
should never taste any substance in the science laboratory. Tell students that they should wash their
hands when they have finished with this activity.
Ask the students to create a data chart with three columns: Before, During, and After in their science
journals or notebooks. In the first column, they should describe the initial appearance of the copper
chloride solution and the piece of aluminum foil, as well as the starting temperature. In the second
column, they should write down any changes they see taking place while stirring the solution and foil. In
the third column, they should describe the appearance of the products and the final temperature of the
solution. Divide students into small groups of no more than four. Once they have put on their goggles,
aprons and gloves each group should measure out about 4 grams of copper(II) chloride dihydrate
(cupric chloride) crystals. The students should measure 100 ml of water and place it in the 250 mL
beaker. Then they should add the copper chloride crystals, and stir until all of the crystals are
dissolved. Students should now fill a test tube half full of the solution. The thermometer should then
be placed in the solution in the test tube. Tell students to read the thermometer while it is still
submerged in the liquid. They should not remove the thermometer to read it. Students should record
the appearance of the solution and the foil, as well as the starting temperature, in the first column of the
data tables.
Next, the students should take a piece of aluminum foil, place it in the copper chloride solution, and stir
thoroughly for at least five minutes. They should then record all changes they observe, including any
change in temperature. If the reaction is slow to start, have students first crumple the aluminum foil.
This will expose fresh reaction surfaces at the creases. Students will make the following observations:
The blue liquid will turn gray, the piece of foil will break up and “disappear,” some bubbles will form, the
temperature will rise, and a reddish powder will accumulate on the bottom of the beaker. (The gray
liquid will be a solution of aluminum chloride resulting from a single-replacement reaction, the bubbles
are hydrogen from a side reaction, the reddish powder is copper metal, and the temperature rises
because the reaction is exothermic. You do not need to provide this information to students yet,
however.) Finally, instruct the students to carefully pour the liquid down the drain, with goggles still on
and water running, being careful to save the solid material at the bottom of the beaker. They should
scoop out some of this solid material onto a paper towel, dry it, and describe its appearance in the last
column of the data charts. You might want to save some of the powder to show students again after it
has completely dried.
After the students have cleaned up their work stations and washed their hands, remind them that what
they observed was a chemical reaction. Tell them that, during the reaction, the copper chloride and
aluminum combined to produce aluminum chloride (AlCl3) (the gray liquid) and copper (the red
powder). Ask the students to identify which substances were reactants and which were products. (The
reactants were copper chloride and aluminum; the products were aluminum chloride and copper.) Next,
ask the students to think about what evidence they have that this was, in fact, a chemical reaction. Give
them a minute to discuss this question in their groups, then call on students to share their ideas with the
class. Make a list on the board. (New substances were produced, heat energy was released, there was
a color change, gas bubbles and a precipitate were produced.)
Analysis and Conclusions:
1. What evidence did you observe during the demonstration that tells you a chemical reaction has
occurred. List all examples.
[Answer: Energy (heat and light) was released; color changed; gas was given off, different substances
were formed.]
2. What substances reacted during the demonstration? What products were formed in the reaction?
[Answer: Oxygen and sugar reacted. Carbon dioxide and water vapor formed.]
3. What elements were present in the test tube at the start of your experiment? What elements were
there after the reaction? Do not count the hydrogen and oxygen in the water used to dissolve the
crystals.
[Answer: The elements aluminum, copper and chlorine were there at the start. The same elements,
aluminum, copper, and chlorine, were there at the end. ]
4. What evidence did you observe during the reaction in the test tube that tells you a chemical reaction
has occurred? List all examples.
[Answer: Energy was released because the temperature increased. Color change and change in
appearance was evidence that new substances were formed, A solid substance different from
aluminum was formed. Gas bubbles were given off. (Note that this is a side reaction of aluminum with
the acidic CuCl2 solution. Students are not expected to know this.)]
5. Was your hypothesis supported by the results of your experiment? Write a conclusion describing
how you think the chemicals in the test tube changed during the reaction. Use the names of the
elements in your description.
[Answer: Student answers will vary depending on their hypotheses. Sample response: The aluminum
reacted with the copper(II) chloride solution and copper metal was released, while aluminum went into
solution with the chloride. The important point here is that students realize that all elements are still
present but have “rearranged” in some way. ]
In this activity, students will demonstrate the following Inquiry Skills:
• Design Investigations
o Practice lab safety by:
 Following lab safety procedures
 Using test tubes properly
 Recognizing safety equipment and materials and knowing their proper use
• Gather Data
o Use tools and the Use SI (metric) system) to accurately measure:
 Mass with a balance
 Volume with a graduated cylinder
 Temperature with a thermometer
o Use senses to observe:
 Seeing (color, shape, size, texture, motion)
• Use the appropriate format to record data in a lab journal or notebook
 Graph or chart
 Writing (journal, worksheet, electronic text)