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  • Fire is used as a part of these experiments. Please do not perform without an adult.

Learn the differences between chemical and physical change in this series of experiments. We’re playing with paper towels, blowing up balloons, and making all kinds of chemical reactions!

Required Materials

  • paper towel
  • matches or lighter
  • lemon (cut in half)
  • glass cup
  • baking soda
  • food coloring
  • popsicle stick
  • Alka Seltzer tablet
  • flask (or bottle)
  • water
  • 1 balloon

Step-By-Step Instructions

Step 1

Physical Change: In a physical change there can be a difference in the appearance, smell, or simple display of a sample of matter without a change in composition. To explore physical change, crumple up a piece of paper towel and observe that although the paper towel looks different, it is still a paper towel. We can reform it back into its previous state/shape and lay it flat.

Step 2

Chemical Change: In a chemical change a new substance is formed and energy is either given off or absorbed. To explore chemical change, we performed a number of experiments. First, with an adult present, crumple the paper towel back into a ball and use a lighter or match to light it on fire. Quickly drop it into a glass. Note what happens when the oxygen going into the fire is stopped by the glass. Is there a smell? Do you see smoke? After making your observations, be sure to put the fire completely out by pouring water into the glass. Use our fun hand trick from the video to remember that when chemical changes/reactions occur, you’ve mixed two things together to make something new! Another important thing to remember – you cannot reverse a chemical change, whereas you can reverse a physical change.

 

Step 3

We continued to explore chemical reactions with another experiment! ​​Put half a lemon into a cup, so that the rind is facing downwards, and put a spoonful of baking soda on top of the lemon. Add a few drops of food coloring on top of the lemon and baking soda. Take a popsicle stick and push the baking soda down into the lemon. Note what happens when the citric acid from the lemon and baking soda mix and a chemical reaction takes place!

Step 4

For our last experiment, we used a chemical reaction to blow up a balloon! Break up an Alka Seltzer tablet and put the pieces inside a balloon. Fill up your flask or bottle about halfway with water. Then stretch the balloon with the Alka Seltzer pieces over the opening of the bottle (you’ll probably need to hold the Alka Seltzer pieces in the bottom of the balloon as you do this. It helps to have two sets of hands!). Drop the Alka Seltzer pieces from the balloon into the water. Shake up the bottle and note what happens to the balloon!