Type of Scientific Investigation: Cause of oxidation or rusting of metals (such as irons)
Problem: What causes iron to rust?
Hypothesis: If a metal such as iron is exposed to water and oxygen, then it will rust.
Variables - Experimental Group(EG) - Control Group(CG)
- Metal object - Nails (EG and CG, 1-3 trial)
- Presence of liquid (Deionised water) - Present, Absent (EG and CG, Present on 1-2 trial, absent in 3rd trial)
- Presence of oxygen - Present, Absent (EG and CG, Present on 1st and 3rd trial, not present on 2nd trial)
- Presence of boiled Deionised Water - Present, Absent (EG and CG, Present on 2nd trial, Absent on 1st and 3rd trial)
Materials :
- Iron nails
- Container
- Deionised water
- Boiled Deionised water
- Oil
- Calcium Chloride
Procedure :
- Label containers 1-3
- About 1/4, fill container 1 with deionised water and add a nail.
- About 1/4, fill container 2 with boiled deionised water and add a nail. Carefully pour a little oil over the surface to prevent air from reaching the water.
- Put a nail into container 4 and add about 2 cm depth of anhydrous calcium chloride granules (these absorb water). Put a bung in this tube to prevent any further water from getting in.
- Leave for at least three days and then note any changes in appearance of the nails.
- Container 1 - water and air
- Container 2 - water, no air (air removed during boiling and the oil prevents any extra from dissolving in the water and reaching the nail)
- Container 3 – air, no water (the calcium chloride removes the water from the air and the bung prevents any extra from entering)
