Inorganic Chemistry

Know the Reactivity Series

Potassium, Sodium, Lithium, Calcium, Magnesium, Aluminium, Zinc, Iron, Copper, Silver, Gold

When does rusting of iron occur?

When water and oxygen are present

How can rusting be prevented?

Barrier Method (Painting/Oiling) , Sacrificial Protection, Galvanising

Explain the Barrier Method (Painting/Oiling)

The barrier method involves painting a protective layer, such as paint or oil, to iron surfaces to prevent it coming into contact with water and oxygen. However, if the coatings are washed away or scratched, the iron is once again exposed to water and oxygen and will rust, once iron begins to rust it will continue to corrode internally as rust is porous and allows both air and water to come into contact with fresh metal underneath.

Explain Sacrificial Protection

This prevents iron from rusting through the reactivity series where a more reactive metal can be attached to a less reactive metal. The more reactive metal will oxidize and corrode first, protecting the less reactive metal from corrosion. The more reactive metal will lose electrons more easily and is oxidized more easily. For continued protection the more reactive metal needs to be replaced before the completely corrode.

Explain Galvanization

The iron is covered with zinc, this can be done by electroplating or dipping it. If the coating is damaged or scratched the iron is still protected through sacrificial protection.

Where are reactive metals found?

Reactive metals are found in ores where they are usually chemically combined with other substances found in the earth’s crust. These need to be extracted chemically with processes such as electrolysis or reduction with carbon.

How are unreactive metals usually found?

They are usually found as an uncombined element. These do not have to be extracted chemically.

Uses of High carbon Steel and main property

Tools and chisels - Very hard

Uses and main property of Low Alloy Steel

Construction Bridges, high speed tools - Hard and strong, Low malleability and ducitility

Uses and main property of Stainless Steel

Cutlery, Sinks, Chemical Plants - Strong and resistant to corrosion

Explain properties of aluminum and its uses

Aircraft Bodies - High strength-to-weight ratio (low density)

Saucepans - Unreactive and good conductor of heat

Food cans - Non-toxic, resistant to corrosion and acidic food stuffs

Explain properties of copper and its uses

Electrical wiring - very good conductor of electricity and ductile

Saucepans - Good conductor of heat, unreactive and malleable

Water pipes - Unreactive and non-toxic

Explain properties of iron and its uses

Building material - Good strength, malleable and ductile

Catalyst - Increases rate of reaction without being used up