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Learners observe two joined glass tubes containing a conductive salt solution. Electrodes are passing an electric current through the water. Oxygen gas is formed in the tube connected to the positive electrode. Hydrogen gas is produced in the tube connected to the negative electrode. As the gases are formed, they float to the top where they can be collected for demonstrations: 1) a hydrogen-filled tube will make an exploding sound when lit; 2) an oxygen-filled test tube will re-light a glowing splint; and 3) a hydrogen- and oxygen-filled rocket can be launched across the room. This is an exhibit and demonstration in OMSI's Chemistry Lab and would make a good demonstration for classroom students or other learners.

Quick Guide

Preparation Time:
1 to 2 hours

Learning Time:
Under 5 minutes

Estimated Materials Cost:
$10 - $20 per group of students

Age Range:
Ages 11 - adult

Resource Types:
Activity, Demonstration, Exhibit


Materials List (per group of students)

  • Hoffman electrolysis apparatus (WARDS Biology/lab Supplies, 1-800-962-2660)
  • Bobbitt low-Voltage (12V DC) Power Supply (Carolina Science and Math, 1-800-227-1150)
  • Concentrated H2SO4 (sulfuric acid) (keep 100 ml on hand)
  • Two clean, dry, medium-sized test tubes
  • 10-ml graduated cylinder
  • 600-ml beaker
  • Deionized water (dH2O) (keep 500 ml on hand)
  • Wooden splints
  • Candle
  • Butane lighter or matches


  • Physical Sciences
    • Electricity and Magnetism
      • Electric Charges and Currents
    • Chemistry
      • Chemical Reactions
    • States of Matter
      • Gases


To use this activity, learners need to:

  • see
  • see color
  • hear

Learning styles supported:

  • Involves hands-on or lab activities


This resource is part of:

Access Rights:

  • Free access



Funding Source:

  • National Science Foundation