Program 7: Having a “blast” with Geysers and Rockets

For our final Science Explorers Club program of the summer, I wanted all of our young scientists to have fun with some nifty (and sometimes messy) demonstrations and experiments. Our line-up for the evening included:

  • Inflated plastic bag “pillows” using baking soda, vinegar, and water
  • Film canister “rockets” using water and Alka-Seltzer tablets
  • My 2-liter bottle rocket demonstration
  • Soda & mentos geysers
  • …plus a little something unexpected at the end 🙂

In all of our demonstrations, carbon dioxide gas played a key role… [NOTE: For all of our demonstrations, I made sure that every scientist had a pair of safety glasses, just to be safe!]

The Exploding Lunch Bag (via Science Bob)


  • A zip-top plastic sandwich bag for each scientist (I used the kind with an actual zipper so they were easier to close)
  • Baking soda (3 tsp. per scientist)
  • Distilled white vinegar (1/2 cup per scientist)
  • Paper towels (you’ll need to provide each scientist with a palm-sized square)
  • Water (room temperature, or warmed if possible) (1/4 cup per scientist)

bag bombThis is a very simple way to demonstrate and actually see a chemical reaction unfold before your very eyes, combining liquids and a solid to create a gas!  There are a lot of versions of this demo online – I chose to follow Science Bob’s version. First, you pour 1/4 cup of water (warm, if possible) into a Ziploc bag. Next, you add 1/2 cup of distilled white vinegar to the bag. That’s all of our liquids. You then put 3 teaspoons of baking soda onto the center of a paper towel square (about the size of your palm), and fold it up into a little packet. You drop the baking soda packet into the bag, zip it closed as quickly as possible, and then watch the resulting reaction. All scientists in our group ended up with very firm “pillows” composed mostly of carbon dioxide gas – none of them exploded. If we were to repeat this experiment, I would probably use the kind of zip-closed bags that are just a closing seam (no zipper) since I think there was a small continuous leak of gas through the actual area where the zipper was positioned.

Film Canister “Rockets”


  • 1 empty 35 mm film canister [If you can’t find any around the house, you can purchase these online from several places – I got mine from the Steve Spangler store]
  • 1 Alka-Seltzer tablet per scientist
  • Water for each scientist

film canister rocketYou simply put a small amount of water in the film canister (fill it about 1/3 full), add 1/2 to a full tablet of Alka-Seltzer, firmly put the cap back on the container, put it lid-side down on a flat surface (preferably outdoors), and then stand back and wait for the reaction. The Alka-Seltzer reacts with the water and releases carbon dioxide. When the carbon dioxide expands so much that it no longer fits inside the sealed film canister, the canister blows apart and it shoots straight up into the air. Here is a fun video of Science Bob’s guest appearance on the Jimmy Kimel show…with film canister rockets galore!

My Soda Bottle Rocket Demonstration


  • 1 empty 2-liter soda bottle
  • 3 unsharpened pencils
  • Some tape (I used duct tape)
  • Distilled white vinegar
  • Paper towel or tissue (a palm-sized piece)
  • A cork that fits into the mouth of the bottle

DSC_0084I got the idea for this experiment online from the blog (“Epic Bottle Rocket“). The mom who writes this blog didn’t provide a lot of specifics in terms of measurements, so I did what all good scientists do – I tested until I was happy with the result 🙂 First, holding the bottle mouth-side down, I taped the 3 pencils onto the bottle to act like the rocket “legs” (see the picture to the right). I then poured about 2-3 inches of vinegar into the bottle. Using the same method from our Bag Bombs above, I put 1-2 tablespoons of baking soda into the center of a paper towel square…but unlike the Bag Bombs, I rolled the packet into the shape of a tube so that I could easily push it into the soda bottle. Once I added the baking soda packet, I firmly pushed the cork into the mouth of the bottle, turned it upside down and stood it on its legs on a foam board on the lawn. In a few minutes, once enough carbon dioxide gas had been released from the chemical reaction between the baking soda and the vinegar, the pressure pops the cork out and sends the bottle flying! And to quite an impressive height, I might add. We did this one twice during the program. The second time – at a young scientist’s request – I added twice as much vinegar. We definitely had a rocket launch, but with the additional liquid weight in the bottle, our rocket did not go nearly as high…

Soda Geysers & Mentos Candies


  • One 2-liter bottle of DIET soda per scientist
  • One roll of MINT Mentos candies (you’ll only need about 6 per scientist)
  • Preferably one Mentos Geyser Tube (I got mine from Steve Spangler’s web site)

You can find instructions for this demonstration all over the internet, but I always prefer getting my advice directly from Steve Spangler when possible 🙂 And while a handy Mentos Geyser Tube makes this demonstration very easy to complete, you can also create your own tube by simply rolling a piece of paper (wide enough to hold a stack of Mentos candies). If you choose to create your own tube, make sure you also have a piece of firmer paper or cardboard beneath the tube that you can then pull out to release the Mentos and drop them into the soda when you’re ready to go. Also, while this experiment can work using various types of soda, the hands-down favorite appears to be diet name-brand sodas. There are various theories for why diet coke is a champion product, but using a diet soda is definitely preferred since there is less sugar in the soda and thus less sticky mess after the eruption🙂 Our SEC scientists tested a variety of diet sodas – from name brands like Diet Coke, Diet Pepsi, and Diet 7-Up to store brands of similar sodas. Based on the results of our geysers, the name brands definitely produced the highest geysers – our wimpiest geyser was a store brand diet creme soda.

Why do Mentos candies create a soda geyser? When the Mentos are dropped into the soda, the hard coating on the candies helps to break apart the water molecule bonds that surround the carbon dioxide molecules…which allows the carbon dioxide to expand dramatically, and very quickly. Hence, the soda geyser eruption.

Interestingly, this demonstration first became popular in the 1980’s when teachers and educators used wintergreen Lifesavers candies for the same reaction. But along the way, the makers of these Lifesavers slightly altered the size, making the candies a smidgen larger…and they no longer could simply be dropped into the mouth of a soda bottle. A focused search led educators to Mentos candies – the perfect size AND capable of creating the same dramatic soda geysers.

Below is a video highlighting a few of our moments from the day. I look forward to seeing all of my SEC scientists in the Fall at Prosser Library for some more fun with science 🙂