In this activity you will play with exothermic and endothermic processes! During an exothermic process, energy is released. During an endothermic process, energy is absorbed. How do you know whether energy was released or absorbed? You can see released energy when you activate a glow stick. You can smell released energy when a match is lit. You can hear released energy when a firecracker goes off. You can feel released energy when things get warmer. You can feel absorbed energy when things get colder. Supplies:
1 glow stick
2 teaspoons Epsom salts
1 tablespoon water
1 teaspoon yeast
1 tablespoon hydrogen peroxide
2 plastic zipper baggies
Activity 1:
Put some water in a small bowl or cup – you don’t want it to be super warm or super cold - room temperature or slightly warm water works best. Add 2 teaspoons of Epsom salts to a zipper bag. Tilt the bag to collect the Epsom salts in a corner, and add 1 tablespoon of your room temperature water.
Gently squish/knead the bag to help the Epsom salts mix with the water. What do you notice? Do the Epsom salts dissolve? Form a solid? Make bubbles? Does the bag feel warmer or colder? Is this an endothermic or an exothermic process?
Hint: an endothermic process will turn colder, an exothermic process will turn warmer.
Activity 2:
Add 1 teaspoon of yeast to a clean zipper bag. Add 1 tablespoon of hydrogen peroxide to the bag, gently press most of the air out of the bag, and zip it up.
Tilt the bag back and forth a couple of times to help the peroxide come into contact with the yeast. Gently squish/knead the bag to continue mixing the yeast and peroxide. What do you notice? Does the yeast dissolve in the peroxide? Form a solid? Make bubbles? Does the plastic bag stay the same size or does it expand? Does the bag feel warmer or colder? Is this an endothermic or exothermic process?
You may have noticed the bag inflate. Oxygen gas is produced when the hydrogen peroxide comes into contact with an enzyme called catalase found inside the yeast cells.
Activity 3:
Find your glowstick and bend it gently to crack open the tiny glass vial inside that looks like a bubble.
As hydrogen peroxide is released from this vial, a chemical reaction happens that causes the dye molecules inside to become energized. As the dye molecules lose energy, light is released making your glowstick glow.
Is the release of light an endothermic or exothermic process?
Cleanup: safe to throw the glow stick in the trash, and to wash and reuse the bags or toss in the trash.
Click below to download a pdf of the Energy Exploration DIY science kit for easier printing.
Make messes, have fun and spread science joy!
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