S3.6.5 For the adult
Rusting and other reactions
Why do iron nails turn orange-brown outside, but stay shiny in a dry drawer?
What this chapter teaches
Iron rusts when it has oxygen from the air and water at the same time. Rust is a new substance, hydrated iron oxide, so rusting is a chemical change. A word equation shows a reaction: reactants, then an arrow, then products. A rusted nail weighs more than the iron, because oxygen and water have joined it.
Three questions to ask
There is no one right wording. Listen for the idea.
- What two things does iron need to rust?
- How could you stop a gate from rusting?
- Which side of a word equation holds the reactants?
After the chapter, the learner can
- Write word equations for rusting and other reactions
- Test what iron nails need to rust, using three jars
What they copy into their notebook
Iron + oxygen + water → hydrated iron oxide. Iron needs air and water to rust. Reactants go before the arrow, and products go after it.