5) Rusting

Question 1

What causes iron to rust?

Answer 1

Water and oxygen

Question 2

Why would an iron nail in salt water rust more than an iron nail in tap water?

Answer 2

Because salt increases the rate of rusting

Question 3

What is the equation for iron rusting?

Answer 3

Iron + oxygen -> hydrated iron oxide (this is the chemical name for rust)

NOTE:
WATER MUST GO ON THE ARROW x It must be present for rusting to take place.

Question 4

Ways to prevent rusting:

Answer 4

SACRIFICIAL PROTECTION
GALVANISING
PAINT
OILING
RUBBER COATING
(Bottom 3 are known as barrier methods)

Question 5

How does sacrificial protection work?

Answer 5

It attaches big blocks if magnesium to iron (usually on a ship/ water pipe)

Magnesium is more reactive than iron, so it corrodes the iron, leaving it intact.

Question 6

How does Galvanising work?

Answer 6

The metal is covered in a thin layer of zinc.

The zinc creates a physical barrier between the metal and air and water.

Zinc is also slightly more reactive than iron, so it corrodes it, leaving it intact.

Question 7

Iron (rusts/ corrodes)

Metals (rust/corrode)

Answer 7

Rusts
Corrodes