Chem: corrosion of metals

IGCSE

Define rusting

the corrosion of iron and steel to form rust ( hydrated iron) via oxidation

conditions required for iron and steel to rust..?

1. water

2. air

state the equation for rusting

iron + water+ oxygen ——> hydrated ron (II) oxide

name two ways to prevent rusting

barrier protection

sacrificial protection

Galvanising

define each of them.

Galvanising = the protection of iron and steel by covering the outer layer with zinc

Barrier method= coating the layer to prevent the iron/ steel to be contact with air and water

sacrificial method = when more reactive metals corrode in preference to less reactive ,etals where they lose elctrons in prefernce to iron

methods of barrier protection

1. Greasing

2. Painting

3. Plastic coatings

Explain why galvanising is both an example of barrier and sacrificial protection

since galvanising is the protection iron/ steel by coating it with a layer of zinc there are strictly two ways of galvanising one of the being barrier which is the same methos, and the second on ie sacrificial protection due to zinc being more reactive than iron.