U3-2-6 - Corrosion

Question 1

Corrosion

Answer 1

A chemical reaction in which the surface of a metal changes from an element to a compound.

Question 2

More _________ metals corrode faster.

Answer 2

reactive

Question 3

Rusting

Answer 3

Corrosion of iron and steel

Question 4

What is required for rusting to occur?

Answer 4

Oxygen and water

Question 5

During rusting, iron atoms change into _____.

Answer 5

iron ions

Question 6

Rust indicator

Answer 6

Ferroxyl

Question 7

Colour change of ferroxyl indicator

Answer 7

Yellow to blue (if iron ions present)

Question 8

Name the two types of rust prevention.

Answer 8

Physical and electrochemical

Question 9

Electrochemical protection prevents rusting by __________.

Answer 9

providing iron with electrons

Question 10

Physical protection prevents rusting by _______.

Answer 10

keeping oxygen and water away from the metal surface

Question 11

When using sacrificial protection, you attach iron to _____.

Answer 11

a metal above iron in the ECS (e.g. Mg)

Question 12

How does sacrificial protection prevent rusting?

Answer 12

The metal attached to iron corrodes and gives its e⁻ to the iron.

(Iron only rusts if the other metal is fully corroded.)

Question 13

Give one example of a substance used for physical protection from rusting

Answer 13

Any one of:

paint, oil, wax, grease, plastic, zinc (galvanising)