Science Experiment: Alka Seltzer Grenades

This Alka Selzer Grenade experiment is similar to the Baking Soda Rocket experiment but instead of the bottle launching into the air by itself, you throw the grenade. The grenade explodes due to the build up of pressure and the impact of the bottle hitting the ground.

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Science Experiment: Alka Seltzer Grenade

Safety Goggles, please wear at all times.
1/2 cup white vinegar
3 antacid tables, like Alka Seltzer or generic store brand
1 small empy water bottle
Food coloring (optional)

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Science Experiment: Alka Seltzer Grenade

Step 1. Measure and pour vinegar into empty bottle. Add a few drops of red food coloring (optional). Break the antacid tablets into halves.

Step 2. Go outdoors. Add the 3 antacid tables quickly to the bottle of vinegar. Put the cap on. Make sure it’s closed tightly. Wait for the antacid and vinegar to react. You will feel the bottle getting firmer as the gas inside the bottle expands. Wait to the point where you may see the sides of the bottle bulge a bit.

Science Experiment Alka Seltzer Grenade - alka seltzer reacting with vinegar in bottle

Step 3. Go to an open area where there is a hard surface, like pavement or driveway. Throw the bottle as high as possible. When it lands, you should see an explosion and/or propulsion of the bottle. Make sure you keep a distance as the bottle may bounce back and hit you! Depending on how it lands on the ground, when the gas escapes from the bottle it can propel the bottle forward or backward so keep a safe distance. Sometimes the bottom of the water bottle gets blown away, and sometimes the top of the bottle cap.

Science Experiment Alka Seltzer Grenade - cap top broken off by impact

What just happened?

The vinegar (acid) and antacid tablets (sodium bicarbonate) reacts to form a gas. The gas that is formed is carbon dioxide. There is not enough volume or space for the gas in the bottle so that’s why you will see the sides of the bottle bulging. When the bottle hits the ground and breaks, the gas bursts out, the cap usually breaks and the bottle propels forward like a rocket.

Take this further:

Try different kinds of vinegar to see if that has any effect on the rocket: apple cider vinegar, balsamic vinegar, white vinegar, etc.
Vary the proportion of alka seltzer and vinegar and see if there is a difference in reaction and results.
Experiment with different size bottles. Do some bottles, 8 ounces, 16 ounces, etc. produce a different result?
What kind of result did you get?