Physical and chemical changes experiments are a hands-on way to engage middle school students in learning how matter reacts and transforms. These five activities will have students differentiate the differences between a physical change and a chemical change while having a lot of fun. Depending on your classroom, you may choose to do these as demonstrations or allow students to work in small groups.
A physical change is a change in the size, shape, or state of matter.
A chemical change is a change that creates something new.
Signs of Chemical Change
When a chemical change happens, a brand-new substance is formed, and there are usually some clear signs that let you know! Here are a few common clues that a chemical change has taken place:
Color Change – The substance turns a different color (without mixing in a dye or paint).
Temperature Change – It gets hot or cold without adding heat or cooling it yourself.
Gas Production – You might see bubbles or fizzing, even though you didn’t boil it.
Light or Sound – Some chemical changes release light (like fireworks) or make noise.
Formation of a Solid (Precipitate) – Two liquids mix and form a new solid substance.
If you notice one or more of these signs, chances are good that you’re seeing a chemical change in action!
5 Experiments to Explore Physical and Chemical Changes
1. Baking Soda and Vinegar Reaction (Chemical Change)
This experiment is an easy win to incorporate into your physical and chemical changes unit if you’re on a budget. Baking soda and vinegar are two staples in most kitchens. Bring these materials into your classroom.
Once you combine the two materials, students will be able to see bubbles form. Bubbles are one way to tell that a chemical change has occurred as it is a new substance that forms when baking soda and vinegar combine.
This physical and chemical changes experiment will take a few days to observe before seeing the results, but it’s a great example of a chemical change. To complete this experiment, you will need:
- An egg
- A glass
- White vinegar
Discuss the egg with the students. Then, ask them to predict what they think will happen when the vinegar meets the egg. Throughout the 3 days, students should observe that the eggshell breaks down because of the acid in the vinegar. Eventually, the entire eggshell will disappear, leaving just the insides of the egg.
Why does this happen? This chemical change occurs because the egg actually has little holes in its shell. The vinegar, an acid, finds its way into these tiny holes and starts to break it down. However, the egg’s insides will remain intact because a membrane surrounds it, holding everything together.
3: Gas Balloons (Physical Change)
Another fun but easy experiment to use in your classroom involves soda and a balloon. Take a 1-liter bottle of any brand of soda and place a balloon around the mouth of the bottle.
This experiment will take approximately ten minutes to observe the changes.
Over time, students should observe that the balloon begins to fill up and expand in size.
This experiment can be used to see if students are thinking critically about examples of chemical and physical changes. For example, while I teach students that bubbles can indicate a chemical change, the bubbles need to be a new substance. Since the bubbles are already in the soda bottle, this is not a chemical change. In addition, the size of the balloon is growing because the carbon dioxide from the soda is spreading out to fill the space in the balloon, which is a physical change.
4: Does surface area affect the rate of melting? (Physical Change)
This activity is another example of observing a physical change. The materials are simple,
- ice cubes,
- a timer
- a ruler
Students will use the timer to calculate how long it takes ice cubes of different sizes and shapes to melt. Then, students can make comparisons for crushed or cubed ice. Next, have students use the ruler to determine the surface area of the cubes, but caution them from touching the cubes as their body heat will affect the melting rate.
Since this activity is monitoring a change of the state of matter, it is a physical change. However, students will enjoy working with the ice cubes, and the simplicity of this activity is perfect for integrating into your science classroom.
5: Digestion (Chemical Change)
These physical and chemical change experiments are perfect for building student understanding in a fun and interactive way. For example, this experiment will mimic how the muscles of the human body help break down food to be digested.
For this experiment, you will need:
- 2 Ziploc bags
- Various food inside the bag
- 1/2 c Water
- Timer
Fill the same types of food inside each bag, trying to keep them as similar as possible. Pour about 1/2 c of water into each bag. Set your time for 5 minutes. Allow the bags to remain as they are.
After 5 minutes, mimic the movement of the stomach muscles to break down the food. Often, this is a classroom demonstration, so I will call students up to squeeze the bag to resemble stomach muscles.
Put the bags down, have students make observations, wait another five minutes, and repeat. Students should observe that the food in the bag that has muscle contractions will break down more than the other bag.
While this demonstration shows a physical change, remind students that acids and enzymes help to break down food further, which is a chemical change.
Want Your Students to Master This Concept?
Grab a FREE Chemical and Physical Changes Student Choice Pack — filled with ready-to-use activities, experiment ideas, graphic organizers, and even a tic-tac-toe board to make homework or early finisher work more engaging. It’s the perfect companion to the experiments in this post!
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These are 5 super easy experiments to integrate into your physical and chemical changes unit. If you are looking for ready-made resources to use, check out the following:
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