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Corrosion Experiment

Name of Corresponding Unit Plan: Artifact Conservation

Grade Level: 8-12

Common Core Standards:
RS.3. Follow precisely a complex multistep procedure when carrying out experiments.

RH/S.7. Conduct short as well as more sustained research projects to answer a question or solve a problem.

Content Areas: Science

Recommended Length/Duration: Initially one 45-60 minute lesson, 5-10 minute daily observations, 30-60 minute summary of findings

Learning Goals: Students will observe the changes in test samples over time.

Students will understand the factors that affect the process of corrosion.

Description/Sequence:

  1. This experiment should follow a discussion on the chemistry of corrosion.  Discussion questions might include:
    • What conditions are necessary for corrosion to take place?
    • What factors do you think will retard or accelerate corrosion?
    • What evidence of corrosion might we observe?
    • What will the rate of corrosive action be?
  2. The teacher should decide how many test samples students should observe.  The class may test three different metals in multiple samples or each student may test a different sample.  All samples may use the same electrolyte or several different solutions may be tested.
  3. Have students prepare metal samples and glass jars for the testing apparatus. The metal samples should hang from fishing line so that it does not touch the sides of the jar.  Jar lids should fit loosely to keep the electrolyte from spilling, but allowing gas to escape from the chemical reaction.
  4. Have students describe the characteristics of each test sample on their worksheet and hypothesize on the reaction they anticipate.
  5. Pour electrolyte solution into the jars and close the lids of the jars loosely.  Set the jars in a safe place where they will not be disturbed, but can be easily observed.
  6. Have students make daily observations for two weeks.  Have them describe in detail any changes they can see.  The teacher may lead periodic discussions about the comparative progress of the reactions.
  7. At the end of two weeks have students report out on the outcomes of their experiment.  These should be recorded on their worksheet and then shared as part of a class discussion. Discussion questions might include:
    • How did each sample change over time?
    • What evidence of corrosion took place?
    • Which samples showed the most corrosion? The least?
    • What metals would be best for use in corrosive environments?
    • How could this information be applied in engineering?

Assessments: Informal assessment of student worksheets for accuracy and effort.

Materials/Resources: Corrosion Experiment Worksheet (pdf). Various sample metals (iron, stainless steel, copper, brass, silver, gold, etc.) Clear glass jars large enough for samples to hang in Electrolyte. Suggested corrodents are limited to common substances for safety and convenience: household bleach (diluted with tap water in the ratio of 100:1), ammonia, Drano, weak hydrochloric acid, weak sulfuric acid, rain water, or calcium chloride solution (similar to road salt).

Special Considerations: Safety precautions for using acids should be employed.

The scale of this experiment can be easily adjusted by limiting or adjusting the number and kinds of samples tested.

Extensions: Students may want to test additional samples or adjust other variables in the testing situation.

Students may want to learn more about materials specifically designed to resist corrosion.