Name _________________________________ Date _______ Period _______
Physical and Chemical Changes Lab
Experiment 1: Popcorn
Using the air popcorn popper, place a small amount of popcorn in the top yellow lid. Lift
up on the yellow handle to drop the popcorn into the metal chamber. Put the switch to on and
observe what happens.
Draw a picture of the popcorn before it pops, and what it looks like after it pops.
Before
*
After




1. What happened to the popcorn?
2. What caused this to happen to the popcorn?
3. Is this a chemical or physical change? Why?
4. Is this a homogeneous or heterogeneous mixture?
5. How could you make it a heterogeneous mixture?
Experiment 2: Heating of Sugar
In an aluminum pan, place a small scope of sugar. Place the pan on the ring stand. Put
your goggles on and light the candle. Observe the changes that occur. Remember the
chemical formula for sugar is C6H12O6
*Draw the contents of the pan before and after heating. Also describe what the sugar looks like
before and after heating.
Before
*
After


1. While watching the pan being heated, list the things you observe happening.
1.
2.
3.
4.
2. Sugar is a _____________________________(compound element, or mixture)
3. What substance escapes from the pan when it is being heated?
4. What substance is left in the pan after the sugar has been broken down?
5. Is this a physical or chemical change? Why?
Experiment 3: Hand warmer------Observe the contents of the hand warmer in the beaker.
1. What do you see?
2. Is it a heterogeneous or homogeneous mixture?
Take the hand warmer you have been given and shake it for 1 minute.
1. What do you notice?
2. Is this a physical or chemical change? Why?
3. Is this an endothermic or exothermic reaction? How do you know?
Experiment 4: Glow stick--------Observe the unlit glow stick.
1. What do you see?
2. Is it a heterogeneous or homogeneous mixture?
Observe the lit glow stick.
3. What do you see?
4. Is it a heterogeneous or homogeneous mixture?
5. . Is this a physical or chemical change? Why?
In the following experiment, you'll observe the differences in the brightness of the light given off
from a light stick placed in hot water and an identical light stick placed in cold water.
1. In a darkened room, remove one light stick from its package and feel the outside of the light stick to
determine its approximate temperature.
2. Bend the light stick until you hear it “snap” and the liquid begins to glow. Shake the light stick to mix
the liquid inside. Feel the outside of the light stick again. Has the temperature changed?
3. Ask an adult to fill one of the glass containers with cold water (a mixture of water and ice) and the
other with hot water. Ideally you would like to have the hot water around 50 degrees C / 120 degrees F.
Be careful not to make the water too hot (above 70 degrees C / 158 degrees F) because it can melt the
plastic of the light stick. Never place a light stick in water that is being heated.
4. At the same time, place one light stick in the hot water and place one light stick in the ice water. Leave
the third light stick at room temperature.
5. How long does it takes for a change to occur in the hot-water light stick and in the ice-water light stick?
What happens to the light intensity or brightness of each light stick? Look closely at the hot-water light
stick without removing it from its container. Notice the bubbles rising to the top of the light stick.
6. Compare the rate of bubble formation between the three light sticks. If you have difficulty seeing the
bubbles forming, you may have to remove the light sticks from their containers and hold them up to a light
source such as a window.
7. What causes the bubbles to form? After a few minutes, reverse the light sticks so that the warm light
stick will be placed into the cold water, and the cold light stick into the warm water.
8. How long does it takes for the intensity to change (how long will it take the dim light stick to brighten,
and the bright one to dim)?
9. Remove the light sticks from the hot water and the ice water. Allow them to come to room temperature.
What happens? How long does it take for you to observe any changes? –
How Does It Work? When light is produced from a chemical reaction, such as this one, the resulting light
is called “chemiluminescence” (say, “chemy-lew-min-ess-cents). The light is said to be “cool” because no heat is
produced during the reaction. The reaction between the different chemicals in a light stick causes a substantial
release of energy. When the chemicals are mixed, the atoms are excited, causing electrons to rise to a higher energy
level and then return to their normal levels. When the electrons return to their normal levels, they release energy as
light. This process is called chemiluminescence. The chemical reaction in a light stick usually involves several
different steps. A typical commercial light stick holds a hydrogen peroxide solution and a solution containing a
phenyl oxalate ester and a fluorescent dye. The chemical compounds are kept separated in the light stick in two
chambers. The phenyl oxalate ester and dye solution fill most of the plastic stick. The hydrogen peroxide solution is
contained in a small, fragile glass vial in the middle of the stick. The “snapping” or bending action breaks the glass
vial and allows the chemicals to mix. The chemicals immediately react to one another, and the atoms begin emitting
light. The particular dye used in the chemical solution gives the light a distinctive color. The chemical reaction may
last for a few minutes to a few hours to even a few days depending on the formulation. Most light sticks found in the
stores will last for a few hours.
As you discovered in this activity, temperature can speed up or slow down the rate of the reaction. If you
heat the solutions, the extra energy will accelerate the reaction, and the light stick will glow brighter. However, the
light stick will glow for a shorter amount of time. If you place the light stick in cold water, the reaction will slow
down, and the light will dim. So, if you want to preserve your light stick for the next day, put it in the freezer. The
cold temperature will not stop the reaction, but it will slow down the reaction until you warm up the light stick.