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Natural Indicators


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    Oregon Museum of Science and Industry

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Natural Indicators

Learners combine different plant solutions -- made from fruits, vegetables, and flowers -- with equal amounts of vinegar (acid), water (neutral), and ammonia (base). They compare the color changes of each plant solution in each of the three solutions. Learners learn that plant color often depends on acid/base balances. This can be related to the idea that living systems must maintain a constant pH to survive, and that many plants require a specific pH in the environment to grow. This activity is currently used in the Biochemistry and Envrionmental Chemistry Units in OMSI's Chemistry Lab. Cost estimates are per 100 learners.

Quick Guide


Preparation Time:
30 to 45 minutes

Learning Time:
Under 5 minutes

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

Age Range:
Ages 11 - adult

Resource Types:
Activity, Experiment/Lab Activity

Language:
English

Materials List (per group of students)


  • Household-grade NH3 (ammonia) (keep one quart on hand)
  • C2H4O2 (vinegar) (keep one gallon on hand)
  • H2O (water)
  • 24-well microwell plate
  • Three 125-ml or 250-ml dropper bottles
  • Six to ten 60-ml dropper bottles
  • 70% C3H7OH (isopropyl alcohol, 2-propanol) (keep one gallon on hand)
  • Table salt
  • An assortment of fruits and vegetables — examples: red cabbage, blueberry, blackberry, raspberry, cherry, radish skin, , turnip skin, concentrated grape juice, beet, red onion, red apple skin, plum skin, turmeric powder
  • An assortment of flowers – examples: red rose, purple pansy, purple orchid, purple iris, red valerian
  • Six to ten large beakers (500-ml or larger)
  • Three to five petri dishes with lids
  • An assortment of 500- to 1000-ml plastic storage bottles (enough for each fruit/vegetable sample being used)
  • Strainer
  • A blender (optional) (from general storage)
  • Coffee filters (optional)
  • Cheesecloth or other coarse fabric (optional)

Subjects


  • Life Sciences
    • Cells
      • Chemistry of Life
    • Diversity of Life
      • Plants
  • Physical Sciences
    • Chemistry
      • Acids and Bases
      • Chemistry of Life
      • Solutions

Informal Categories


  • Food and Cooking
  • Nature and Environment

Audience


To use this activity, learners need to:

  • see
  • see color
  • touch

Learning styles supported:

  • Involves hands-on or lab activities

Other


Components that are part of this resource:

This resource is part of:

Access Rights:

  • Free access

By:

Rights:

  • All Rights Reserved, Oregon Museum of Science and Industry, ©1997

Funding Source:

  • National Science Foundation

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