In the Classroom

  Science Discipline(s)
  • Chemistry
  • Math
Topics
  • Properties of gas
  • Acid/Base reactions
  • Averages
Activity Title Alka-Seltzer Rockets Materials
  • 4 Clipboards
  • Paper (with charts printed on them)
  • Pencils
  • Stop Watch
  • Meter stick
  • Goggles or Safety Glasses
  • Plastic Canisters (film canisters)
  • Water
  • Alka-Seltzer
  • Paper or Cloth Towels
  Procedure
  • Work in teams of six (two per canister to record time and height, three canisters per team)
  • Fill three canisters with water to about one quarter, three canisters to about half, and three canisters to about three quarters
  • Insert a quarter of an Alka-Seltzer tablet into the first three canisters, cap immediately, and flip upside down onto the ground and stand back
  • Use the stopwatch to time the reaction
  • Use a meter stick to measure the height of the canister
  • Use the chart provided for recording times and measurements
  • Repeat with the other canisters
  • Find an average height and average time for the pop based on the three trials
  • Repeat all steps using half of a tablet and compare results
  • If time allows, repeat all steps with a full tablet and compare results
Quarter Tablet Trial 1 Time Trial 1 Height Trial 2 Time Trial 2 Height Trial 3 Time Trial 3 Height
Quarter water  
Half water  
Three quarters water
   
Half Tablet Trial 1 Time Trial 1 Height Trial 2 Time Trial 2 Height Trial 3 Time Trial 3 Height
Quarter water  
Half water  
Three quarters water
   
Full Tablet Trial 1 Time Trial 1 Height Trial 2 Time Trial 2 Height Trial 3 Time Trial 3 Height
Quarter water  
Half water  
Three Quarters water
***SAFETY*** The reaction causes the canisters to launch into the air. Safety goggles should be worn at all times and a safe viewing distance should be maintained. Be sure to protect head and eyes from flying film canisters.   Questions
  • What factors do you believe will be important in causing the canister to pop the highest? How could you design an experiment to test the effect of these factors on the height of the pop?
  • What factors do you believe will be important in causing the canister to pop the fastest? How could you design an experiment to test the effect of these factors on how quickly the canister pops?
  • What are the averages for each experiment?
  • Which mixture produced the highest pop? The fastest?
  • How is the carbon dioxide produced?
  • How does the carbon dioxide make the canister fly into the air?
  Explanation PK – 3rd Grade: When water and Alka-Seltzer are mixed, the mixture begins to fizz and tiny bubbles of carbon dioxide are produced. When the bubbles pop, the carbon dioxide gas is released. Even though the gas cannot be seen, the gas can be captured inside the film canister until the canister can no longer hold the gas in. Lid and base are pushed onto one another but with enough pressure from the gas, the lid gets pushed off. It happens all at once resulting in a “pop” and the launch of the lid off of the base. 4th – 6th Grade: When water and Alka-Seltzer are mixed, the fizzing bubbles are a chemical reaction that causes a gas called carbon dioxide to be produced. Carbon dioxide is a molecule made of one carbon and two oxygen atoms; it is the gas that we exhale when we breathe. When these molecules are produced inside of closed canister, they build up pressure. Gases occupy space and the canister can only hold a certain amount of carbon dioxide. When the carbon dioxide has filled as much of the canister as it can, pressure has built up and the lid of the canister will pop off to allow the carbon dioxide gas to escape. The carbon dioxide pushes against the water remaining in the canister, forcing the lid off. This in turn sends the canister into the air like rocket.   Middle School: Everything is made of atoms. Bonds are formed between atoms to create molecules. During a chemical reaction, the bonds of some molecules break, allowing the atoms to form new bonds with other atoms. When Alka-Seltzer is mixed with water, a compound called sodium bicarbonate (also known as baking soda) reacts with an acid called citric acid. The reaction between these two substances produces carbon dioxide. The gas released from the fizzing bubbles is this new carbon dioxide molecule. Gases can occupy space and as the volume of a container is filled with gas, the pressure inside is increased. When there is no more space for the gas to occupy, it pushed against the water below it. This causes the lid of the canister to detach, sending water down and the canister up in the air. Next Generation Science Standards
  • K-2-ETS1-3: Analyze data from tests of two objects designed to solve the same problem to compare the strengths and weaknesses of how each performs
  • 3-5-ETS1-1: Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost.
  • 3-5-ETS1-2: Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem.
  • 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved.
  • MS-ETS1-3: Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success
  • MS-PS1-2: Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.