Rusting II - · PDF fileHave you ever wondered The bigger picture What is the cost of rusting? ©cgrahamphysics.com 2016

Rusting II ©cgrahamphysics.com 2016

Starter:

• Rusting of iron or steel needs two things: ____________ and ___________

• The colour of rust is ______________

• The chemical name for rust is ___________

• Which metals can rust?

©cgrahamphysics.com 2016

How is rusting prevented?


Aim

• Describe how rusting can be prevented

Keywords

• Galvanization

• Rust prevention


Have you ever wondered

The bigger picture

What is the cost of rusting?


Starter: collect you experiment

What has happened? ©cgrahamphysics.com 2016

Starter: explain you experiment

Fill in the results section on your own sheet


What affects the speed of rusting?


Rusting at the seaside


Rusting

Salt speeds up the rate at which iron rusts

iron + oxygen + water hydrated iron oxide

Photo of a rusty pier


How can we stop/slow down rusting?


Preventing rust

• Stainless steel

• Protects under normal conditions

• It is expensive


Galvanizing

• A protective layer of zinc is added on the iron object

• Zinc is more reactive than iron and will corrode away before the iron rusts

• Galvanizing is expensive


Protective coating

• Paint, grease, plastic and unreactive metals can be applied to the surface of the iron

• It prevents water and oxygen to reach the iron or steel surface

• Protective coating varies in cost


Rust Prevention

Read through the sheet and answer the questions


Question 1:

The paint prevents oxygen and water getting to the iron.

Painting is much cheaper than the alternatives.

It is like painting the Forth Rail Bridge ©cgrahamphysics.com 2016

Question 2:

Chromium is used to stop water and oxygen from reaching

the iron. It is also shiny which looks nice in bathrooms.

Question 3:

It is much cheaper to make the can out of iron and then cover

it in tin to stop it from rusting

Question 4:

Zinc is more reactive than iron so it reacts first – before the

iron – with oxygen and so stops the iron rusting.

Preventing rusting - answers


New products that contain iron are often boxed with a small

packet of drying agent.

Oiling – oil prevents the air or water to reach the iron or

steel

Preventing rusting

The drying agent absorbs any water that may cause rusting.


Plenary: 3, 2, 1

3. When you think of Rusting what three words come to mind?

2. What 2 questions would you like to ask about Rusting?

1. Write 1 simile or metaphor for Rusting


Key words

• Galvanization - is the process of applying a protective zinc coating to steel or iron, to prevent rusting

• Rust prevention - Surface protection of iron structures or equipment to prevent formation of iron oxide; can be by coatings, surface treatment, plating, chemicals, or other means


Documents

Rusting II - · PDF fileHave you ever wondered The bigger picture What is the cost of rusting? ©cgrahamphysics.com 2016