It's a Gas!

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In this simple activity, learners see the production of a gas, which visibly fills up a balloon placed over the neck of a bottle. Inside the bottle, water and an effervescent antacid tablet are combined. The chemistry of the reaction is that an acid and base in the antacid tablet react once the tablet is dissolved in water, producing carbon dioxide gas. While gases are visible in liquids as bubbles, many gases aren't visible in air. Seeing the balloon inflate helps convince learners that a chemical reaction can produce products we cannot see. Extensions include experimenting with the amount of water, and the temperature of the water.

Quick Guide

Preparation Time:
Under 5 minutes

Learning Time:
5 to 10 minutes

Estimated Materials Cost:
1 cent - $1 per student

Age Range:
Ages 6 - 14

Resource Types:
Activity, Experiment/Lab Activity

English, Spanish

Materials List (per student)

  • Empty 4 oz. plastic bottle, clean
  • Water
  • Effervescent antacid tablet
  • Paper towel
  • Latex balloon (about 30 cm or 12 inches inflated diameter)
  • Clock or timer


  • Physical Sciences
    • Chemistry
      • Chemical Reactions
      • Acids and Bases
      • Solutions
    • States of Matter
      • Solids
      • Gases
      • Changes of Phase
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations


To use this activity, learners need to:

  • see

Learning styles supported:

  • Involves hands-on or lab activities


Access Rights:

  • Free access