Corrosion

Question 1

Define corrosion

Answer 1

the reaction of metals to form compounds causing their properties to change

Question 2

metal + oxygen →

Answer 2

metal oxide

Question 3

metal + water →

Answer 3

metal hydroxide + hydrogen

Question 4

metal + acid →

Answer 4

salt + hydrogen

Question 5

CO₂ + H₂O →

Answer 5

H₂CO₃

Question 6

SO₂ + H₂O →

Answer 6

H₂SO₃

Question 7

What is Al³⁺ used for?

Answer 7

airplanes

Question 8

Write an ionic equation for:
Al + H₂SO₃ → Al₂(SO₃)₃ + H₂

What happens when the electrons move from Al to H⁺ ions?

Answer 8

2Al(s) + 3H₂SO₃(aq) → Al₂(SO₃)₃(aq) + 3H₂ (g)

2Al + 6H → 2Al ³⁺ + 3H₂

The properties of the metal changes

Question 9

Where does corrosion happen?

Answer 9

at the surface of metals

Question 10

Since metal oxides are insoluble, what happens when they corrode?

Answer 10

a protective layer is formed

Question 11

Why does aluminium appear much less reactive than is actually is?

Answer 11

because when the aluminium reacts with the oxygen from the air, it creates a protective layer and therefore the pure metal cannot corrode.

Question 12

What happens when iron reacts with oxygen/water?

Answer 12

it corrodes and rusts

Question 13

Complete the equation:
iron + oxygen + water →

Answer 13

hydrated iron(lll)oxide

Question 14

What does hydrated iron(lll)oxide represent?

Answer 14

rusting

Question 15

What look does rust have?

Answer 15

a flaky look

Question 16

Does rust protect the iron underneath it?

Answer 16

no, oxygen and water can still enter through the flakes of rust and the iron underneath it can still react

Question 17

What are the 2 methods that could be used to protect iron?

Answer 17

1) cover iron with paint, oil, or other metal (best option)

2) sacrificial protection

Question 18

Explain sacrificial protection used on iron

Answer 18

cover iron with a more reactive element that reacts instead of the iron

Question 19

What is the only metal that when used for sacrificial protection has another name? What is that name?

Answer 19

Zn - galvanising

Question 20

What is an experiment that can be used to show the conditions of iron for rusting?

Answer 20

tt 1 - iron, water, air
tt 2 - iron, boiled water, oil
tt 3 - iron, air, CaCl₂
tt 4 - iron, water, salt, air

tt - test tube

Question 21

What are the results for the experiment to show conditions of Fe for rusting and why?

Answer 21

tt 1 - rust
tt 2 - no rust because boiled water removes oxygen and oil prevents oxygen from entering
tt 3 - no rust because CaCl₂ is anhydrous so it removes water
tt 4 - rusts lots because salt is the catalyst for rusting

tt - test tube