Science in Sweatpants: Baking soda and vinegar

With baking soda and white vinegar, you can do countless at-home experiments. Here are three of them.

Safety first: wear eye protection for each of these experiments, adult supervision is highly recommended.

Extinguishing A Candle

  • 2 tbsp. baking soda
  • 2 tbsp. white vinegar
  • Glass or plastic bottle
  • Candle
  • Funnel

Combine your baking soda and vinegar into the bottle and immediately place your thumb over the mouth of the bottle. After about 30-45 seconds, remove your thumb and gently tip the bottle towards the candle’s flame. Don’t pour the solution on the candle, that’s not as exciting.

After a moment, the flame should go out.

This happens because the baking soda and vinegar combination creates carbon dioxide gas, which you’re trapping with your thumb. Once released, the carbon dioxide sinks because it’s denser than air. As the carbon dioxide displaces the air around the candle, it suffocates the flame.


Hot Ice

  • 4 cups of vinegar
  • 1/4 cup of baking soda
  • Saucepan
  • Clear, clean container
  • Stove burner or hot plate
  • Foil or lid to cover clear container

Combine your baking soda and vinegar…slowly…into a saucepan and boil the solution over medium heat for about an hour. The solution will reduce to between ¼ and ½ cup. You’ll want to watch the solution closely towards the end of the boiling time. Once crystals begin to form, stop boiling and remove from heat.

Pour the solution into a clear, clean container and cover it with foil. Let it cool to room temperature. You can do this by leaving it out for a few hours or refrigerating it for 30 to 45 minutes.

After the solution has cooled, collect a few crystals from the saucepan where you boiled the baking soda and vinegar, using a fork or a skewer.

Submerge the crystals into the solution and watch as crystals immediately begin to grow. As the crystals grow, the solution will warm to about 120° F…earning it the title "hot ice".

The science behind the scenes: For this experiment, we’re creating sodium acetate. Combining baking soda and vinegar gives you sodium acetate and carbonic acid. The carbonic acid immediately breaks down into water and carbon dioxide gas. The carbon dioxide gas escapes the solution, creating the fizzing.

After the carbon dioxide escapes, you’re left with sodium acetate and water. At this state, the sodium acetate isn’t concentrated enough for the experiment to work so we need to remove some of the water. We do this by boiling it.

After the solution has been reduced and allowed to cool to room temperature, the liquid is considered supercooled. This is a liquid that cools below its freezing point without freezing. The freezing point of sodium acetate is about 136°F.

You may remember from previous installments of Science in Sweatpants, adding a nucleation site to a supercooled liquid will result in instant freezing. That’s what we see when we add the sodium acetate crystals from the pot into the solution.

As the crystals form, the entire solution heats up. This is considered an exothermic reaction because there is more energy in the liquid solution than there is in the crystals. That excess energy is released in the form of heat.


Bottle Rocket

  • A 16 oz. plastic bottle
  • 3 or 4 pencils (popsicle sticks or thin wooden dowels work too)
  • Tape
  • Rubber stopper or cork
  • Paper towel, separated into layers
  • Baking soda
  • Vinegar

Tape the pencils around the bottle and make sure the ends of the pencils stick out farther than the mouth of the bottle. This will keep your rocket slightly off the ground. Fill the bottle ¼ to ½ of the way up with vinegar.

Then, pour ½ tbsp. to 1 tbsp. of baking soda onto a square of your paper towel. Gently roll the towel so that the baking soda is completely encased.

Go outside and get ready for blast off!

Drop your paper towel pouch into the vinegar, firmly place the rubber stopper into the bottle, then turn the bottle over with the pencils touching the ground.

After a few seconds, the bottle should be airborne.

This happens because the carbon dioxide gas builds up pressure inside the sealed bottle. Once the pressure is too great for the stopper to hold, it’ll be forced out and the rocket will be sent skyward.