Transform classic baking soda science into something fit for Valentines STEM activities with these super-fun fizzing hearts reactions!
My preschooler is a huge fan of vinegar and baking soda reactions.
She always gets really excited when she sees me breaking out the vinegar and baking soda.
She loves watching the fizzy reactions and playing in the mixture when it’s done reacting. We’ve made fizzing rainbows, fizzing ornaments, and fizzing Easter eggs.
This time, I decided to make the experiment Valentine’s Day themed with these fizzing hearts!

My kids had a blast with this simple experiment, and it was so much fun to see the hearts melt away.
How to Do the Fizzing Hearts Reactions Experiment
Kids will love this fun Valentine’s Day twist on the classic baking soda and vinegar reaction science experiment.
It’s a fun way to bring a little love into your science classroom!
Kids will have a blast squeezing vinegar onto their hearts and watching them slowly melt away.
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WHAT YOU’RE LEARNING WITH FIZZING HEARTS REACTIONS
These fizzing hearts are the perfect way to introduce preschoolers to chemical reactions!
When baking soda and vinegar react, it creates a reaction that releases carbon dioxide gas.
This is what causes the baking soda to fizz.
The baking soda and vinegar reaction is what is known as an endothermic reaction, because the resulting reaction is cooler than the surrounding air.
Who knew science could be so fun! You can also learn what is a chemical reaction for kids to complete your chemistry lesson plan.
Also try these other chemical reactions: borax slime, laundry starch slime, melting pokeball, and fluffy slime!
Fizzing Heart Reaction STEM Integration
Science: Try different variables: will changing the temperature of the vinegar alter the reaction? Will other acids cause a reaction? Will adding more base ingredients stop the reaction?
Technology: Try filming the reaction and watch it again later!
Engineering: Do different shapes change how the reaction happens?
Math: See how long it takes for the reaction to stop.
What you’ll need to make fizzing hearts baking soda science:
Disclaimer: This post contains affiliate links at no cost to you for your convenience.
ARM & HAMMER Baking Soda, 13.5 PoundWilton 417-2588 6-Piece Nesting Fondant Double Sided Cut Out Cutters, Hearts
Food Coloring Liqua-Gel – 12 Color Variety Kit in .75 fl. oz. (20ml) Bottles
Heinz Distilled White Vinegar, 1 gallon
Doodle Hog Crafts Arts and Crafts Multi Purpose Medium Organizer Tray Set, Medium (Pack of 4)
- Baking soda
- Heart cookie cutter
- Vinegar
- Red food coloring
- Pipettes (to control how much vinegar is used)
- Small dish
HOW TO DO THE BAKING SODA HEART SCIENCE EXPERIMENT

First, mix just enough baking soda with water to make a paste. Add a couple of drops of red food coloring and mix.
Place your heart cookie cutter into your dish and place the baking soda paste into the cookie cutter.
Mash the paste with your fingers to mold it to the heart shape.
Carefully pull the heart cookie cutter away from the paste and you’ll be left with a heart.

Give the dish to your kids and give them a little dish of vinegar and a pipette.

Instruct the kids to use the pipette to scoop up vinegar and squeeze it onto the baking soda hearts. They will start to fizz and react.

Repeat the process until the reaction stops.
More Valentine’s Science Experiments
These science experiments are all preschool-friendly!
Coding Caterpillar Valentine Challenge