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)
