Using Chemical Change to Identify an Unknown

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In this activity, learners will develop a method to test five similar-looking powders (baking soda, baking powder, cream of tartar, detergent, and cornstarch) with four test liquids (water, vinegar, iodine solution, red cabbage solution). They will use the characteristic set of reactions for each powder to identify an unknown powder, which is one of the five powders they have tested. [Activity is publicly available through a web crawler capture on Activity write-up only, images are unavailable.]

Quick Guide

Preparation Time:
10 to 30 minutes

Learning Time:
45 to 60 minutes

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

Age Range:
Ages 6 - 14

Resource Types:
Activity, Experiment/Lab Activity


Materials List (per group of students)

  • Baking soda
  • Baking powder
  • Cream of tartar
  • Detergent
  • Cornstarch
  • Water
  • Vinegar
  • Iodine solution
  • Red cabbage indicator
  • 5 Popsicle sticks
  • 4 Droppers
  • 10 Small cups
  • Student Activity Sheet


  • Physical Sciences
    • Chemistry
      • Chemical Reactions
      • Acids and Bases
  • The Nature of Science
    • The Scientific Process
      • Asking Questions
      • Conducting Investigations
      • Gathering Data
      • Formulating Explanations

Informal Categories

  • Food and Cooking


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:

Access Rights:

  • Free access


  • Kessler, James H. ; Galvan, Patricia M.


  • All rights reserved, American Chemical Society, 2007