Fizzing Hearts Experiment: A Fun Valentine’s Day Activity

The fizzing hearts experiment is a perfect activity for Valentine’s Day. Your kids will have so much fun with baking soda and vinegar with this cute heart science experiment.

Fizzing Heart Experiment 3

Maybe it’s the fizzing and the bubbles produced by the chemical reaction.

Maybe it’s just super fun using a pipette to suck up water.

Whatever the reason is, my kids loved this Valentine’s Day fizzing heart experiment! Unfortunately, in the end, mommy had to break up a fight between who gets to melt the last heart. Next time I know to make an even number of hearts!

How to Make Melting Hearts



1. Mix the baking soda and a few drops of food coloring in a bowl. You can add more food coloring if you want a darker shade of red. I recommend using a spoon, otherwise, the red food coloring may dye your hands red.

2. Slowly add water to the mixture and stir with a spoon until the dough is moldable. If you added too much water, simply add a little more baking soda to the mixture.

3. Spoon the mixture into the heart silicone candy mold. Use your hands to press the mixture into the mold to ensure the baking soda/water mixture forms into 3D hearts.

Fizzing Heart

4. Put the heart silicon candy mold in the freezer for at least a couple of hours. We left ours overnight since the day got away from us (it happens more often than not as a mom, am I right?).

5. Take out the mold and pop out the hearts. The beauty of using a silicone mold is that you can push the hearts out fairly easily.


6. Put the hearts inside a baking sheet or pan.

7. Use the pipette to suck up the white vinegar.

8. Squirt the vinegar onto the hearts to melt them.

Fizzing Heart Experiment 4

Why do the Hearts Make Bubbles when We Add Vinegar to Them?

Like what we saw in the exploding snowman science experiment, the chemical reaction between baking soda and vinegar creates carbon dioxide. Hence, you observe the bubbles and hear the fizzing sound.

Final Thoughts on the Fizzing Hearts Experiment

I hope you and your kids enjoyed this simple yet fun Valentine’s Day activity! You can really do this science experiment for any occasion, just shape the baking soda/water mixture into whatever shape you like.

If you don’t have pipettes at home, you can just use a spoon to drip vinegar on the hearts. I have also used a dropper and condiment dispenser bottle.

For more Valentine’s Day fun, check out these posts:


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