Ideas for a corrosion experiment and investigation

Teachers Symposium

Blake Museum, Bridgwater 21st January 2010

Suitability

Ages 7+ under supervision. Woks best with small groups. Easy to set up. Low cost. Results a week or so later.

Purpose

To investigate which metals are least likely to corrode wooden sailing ships.

Apparatus

Boiling tubes, corks or bungs to suit, cotton wool, boiling tube racks. [Test tubes will do, but material samples will need to be smaller.]

Materials

Samples of, for example:

Seawater can be simulated by adding a little salt and a small crystal of washing soda to tap water. Genuine seawater is to be preferred, but may need to be filtered.

Method (Teacher instructions)

• Assemble a set of boiling tubes sufficient to hold all the sample materials (or as many as thought necessary).
• Observe and record the appearance of the sample materials.
• Place a sample of each in an empty boiling tube and stopper (care); seal with clingfilm. Use these as controls.
• Place second samples in boiling tubes. Add sufficient seawater to cover most or all of the surface of the sample. Loosely fit a plug of cotton wool in the mouth of each tube.
• Compare and record appearance after (say) a week and (possibly) a month if interest persists.

Teacher-led extensions/variations

Stopper and seal the tubes. Is the corrosion more or less extensive over a given period?

What happens if the nails are first coated in vaseline or painted before immersing in sea water?

Try out nails in wet oak and wet elm over a period.

Reactive metals in water or steam (e.g Ca or Mg). See textbooks.

^[1]  only developed in the 1920s