P4 used vinegar and steel wool to create a chemical reaction. In pairs we soaked the steel wool in vinegar and then put the steel in a sealed plastic cup with a thermometer in it. We left it overnight and had to wait to see the results the next morning. The vinegar removed some of the protective coating on the steel wool and allowed the iron in the steel to rust. Rusting (or oxidation) is a chemical reaction between iron and oxygen. We saw some of the steel change from a shiny silver to a rusty brown colour.