Rust Race: Corrosion on Aging Infrastructure
Reaction rate chemistry, applied to why Detroit's bridges and water mains need protective coatings.
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Standards
HS-PS1-5 — Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of reacting particles on the rate of a reaction.
Why Does This Matter?
Bridges, water mains, and rail infrastructure across Detroit are built largely from iron and steel, and all of it is slowly corroding. Engineers use protective coatings and regular inspection schedules based on exactly the kind of rate data you'll collect in this lab.
Objective
Compare the corrosion rate of iron nails in different environments and explain the results in terms of reaction rate factors.
Materials
- 4 identical iron nails (uncoated)
- 4 clear cups or jars
- Plain tap water
- Saltwater solution
- Vinegar (dilute acetic acid)
- One cup left empty (control/dry air)
- Labels, camera or phone for daily photos
Safety: Handle vinegar carefully and avoid contact with eyes. Wash hands after handling nails and solutions.
Procedure
- Label four cups: Water, Saltwater, Vinegar, and Control (dry, no liquid).
- Place one nail in each cup, adding just enough liquid to submerge the nail in the first three (leave the control dry).
- Record a baseline description/photo of each nail (color, texture) before starting.
- Check and photograph each nail once a day for 5 school days, recording observations of rust (color, coverage %) each time.
- On the final day, rank the four environments from most to least corroded.
Data Table
| Day | Water | Saltwater | Vinegar | Control (dry) |
|---|---|---|---|---|
| 1 | ||||
| 2 | ||||
| 3 | ||||
| 4 | ||||
| 5 |
Analysis Questions
- Which environment produced the fastest corrosion? What does that tell you about the conditions iron needs to rust quickly?
- Why did the saltwater sample likely corrode faster than plain water, even though both contain water and oxygen?
- The dry control nail should show little to no rust. What does this tell you about what's actually required for the rusting reaction to occur?
- Detroit's water mains run underground, often in wet soil. Based on your data, what maintenance strategy would you recommend to slow corrosion in that environment?