Concentrate: Concentrations and Reaction Rates

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Visitors incrementally increase the amount of iodate in three different test tubes containing the same amount of a starch solution. They observe the solutions to see which concentration of iodate reacts most quickly. Visitors learn that the speed of a chemical reaction is dependent on the concentration of the chemicals involved. Chemical reactions may cause color changes. In this experiment, iodate solution and starch mixture react and the color changes to blue-black.

Quick Guide

Preparation Time:
30 to 45 minutes

Learning Time:
Under 5 minutes

Estimated Materials Cost:
$1 - $5 per group of students

Age Range:
Ages 6 - adult

Resource Types:
Activity, Experiment/Lab Activity


Materials List (per group of students)

  • Three extra-small test tubes
  • One test tube rack
  • Three 50-ml beakers
  • One 10-ml graduated cylinder
  • One 30-ml dropper bottle
  • One 250-ml squirt bottle
  • Starch (soluble potato powder) (keep 100 g on hand)
  • 1.0M H2SO4 (sulfuric acid) (keep 100 ml on hand) — OR — 18M concentrated sulfuric acid (keep 100 ml on hand)
  • Na2S2O5 (sodium metabisulfite) (keep 25 g on hand)
  • KIO3 (potassium iodate) (keep 100 g on hand)


  • Engineering and Technology
    • Engineering
      • Chemical Engineering
    • Technology
  • Physical Sciences
    • Chemistry
      • Chemical Reactions
      • Solutions
  • Life Sciences
    • Human Body
  • The Nature of Science
    • Science and Society
  • The Nature of Technology
    • Technology and Society
      • Technology and the Environment


To use this activity, learners need to:

  • see
  • read

Learning styles supported:

  • Involves hands-on or lab activities


Components that are part of this resource:

This resource is part of:

Access Rights:

  • Free access



Funding Source:

  • National Science Foundation