Sandwich Bag Blasts {Learning About Acids and Bases}

Sandwich Bag Blasts {Learning About Acids and Bases}

Learn about acids and bases with a bang! These sandwich bag blasts make a really fun science lesson any day, but especially for holidays like 4th of July or New Year’s!

Sandwich Bag Blasts


  • Plastic sandwich bags
  • Paper towel
  • Baking soda (1-1/2 tbsp)
  • Vinegar (1/2 cup)
  • Warm water (1/4 cup)


  1. Check your sandwich bag for holes. If it’s not water-tight, you won’t get that magnificent BANG that young scientists crave. You can check with a visual inspection or by filling it with water or air to check for leaks.
  2. Pre-measure your 1/2 cup of vinegar and 1/4 cup of warm water. You can use measuring cups or kid-friendly plastic beakers, so that they can be part of the process!
  3. Rip your paper towel into a 6″ square (roughly, into quarters).
  4. Pour 1-1/2 tbsp of baking soda into the middle of one paper towel square.
  5. Fold up the paper towel, so the baking soda is safely nestled inside a pocket.
  6. Add the vinegar and warm water to the sandwich bag.
  7. Quickly, add the paper towel pocket into the sandwich bag and seal it. Emphasis on quickly. (Note: This is not the time to teach your toddler to seal a sandwich bag. Do this step for them!)
  8. Shake, shake, shake the bag to really get the reaction going.
  9. Set down your sandwich bag, step back, and watch it swell, before BANG! The bag pops and you can call yourself the Sandwich Bag Bomb Squad.

The Science:

Almost all liquids can be qualified as either an acid or a base. Acids produce more hydrogen  (H+) ions when added to water, which deems them more acidic. Meanwhile, bases produce more hydroxide (OH-) when added to water, which deems them more, you guessed it, basic. You can thank chemist Svante Arrhenius for this classification system!

Acids (the ones with more hydrogen ions) have a sour taste and can even dissolve other materials (we call that “corrosive”). In fact, the word acid is derived from the Latin word acidus, which means “sour”. An easy example of an acid is our own stomach acid, that helps us break down the foods we eat.

Bases (the ones with more hydroxide ions) can have a bitter taste and tend to be on the more slimy (think: icky) side. We also call bases “alkali” because they are “alkaline” (not acidic). An example of a base would be soap – the soap we wash our bodies with and even laundry or dish soap!

All of these liquids have a place within the pH scale, which ranges from 0-14. Strong acids make up the lower part of the scale (0-4), while strong bases make up the higher part of the scale (10-14). In the middle of the pH scale is 7, which is “neutral” and is neither acidic or basic. An example of a neutral is water!

For this experiment, we’re using the acidic vinegar, with a pH level of about 2.5, and basic baking soda, with a pH level of about 9. The vinegar and baking soda mix together to cause a chemical reaction that quickly produces carbon dioxide. That carbon dioxide fills the bag, runs out of room, and – BANG – pops the bag to continue expanding.

While we tend to think of acids as the more dangerous liquids, both very acidic and very basic liquids are equally dangerous. Professional chemists use strong acids and bases to create big reactions in chemistry labs. So, if you find that you like explosions and reactions, you might have found your future major or career!

When you try this experiment, be sure to come back to the comments to tell us about it! You can also tag us on Facebook or Instagram in your own pictures!

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