Finding Red

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In this chemistry challenge, learners systematically investigate which combination of four solutions produces a deep red color. The four solutions are iron(III) chloride, ammonium thiocyanate, tannic acid, and oxalic acid. Background information explains that it is the iron ions in solution combining with ions from the other solutions to create the different colors. After learners discover the different colors, they are encouraged to add a third solution to see if the color can be changed, an example of how chemical equilibrium can be shifted. This activity may take a bit more time with younger learners. For safety reasons, adult supervision is recommended and can be conducted as a demonstration for younger audiences.

Quick Guide

Preparation Time:
10 to 30 minutes

Learning Time:
10 to 30 minutes

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

Age Range:
Ages 11 - 18

Resource Types:
Activity, Demonstration, Experiment/Lab Activity


Materials List (per group of students)

  • 5 pieces of white paper to provide a colorless background for the well plate
  • 5 24-well plates
  • 20 plastic dropping bottles
  • Dilute solutions of iron(III) chloride, ammonium thiocyanate, tannic acid, and oxalic acid.
  • Wash bottle with distilled water
  • Paper towels for spills
  • A container of clean water
  • A safe container to dump solutions into and seal (waste container)


  • Physical Sciences
    • Chemistry
      • Chemical Reactions
      • Solutions
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations
      • Gathering Data


To use this activity, learners need to:

  • see
  • see color
  • touch

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 Sources:

  • Camille and Henry Dreyfus Foundation, Inc.
  • American Chemical Society