Using Resources

Question 1

What is corrosion?

Answer 1

The destruction of materials by chemical reactions with substances in the environment.

Question 2

What is the key term for the corrosion of iron and its alloys?

Answer 2

Rusting

Question 3

What is rusting?

Answer 3

When iron or its alloys are corroded

Question 4

What is rust caused by?

Answer 4

Air and water on iron (+alloys)

Question 5

What is hydrated iron (III) oxide and what is its equation?

Answer 5

It is rust and is formed by iron + oxygen + water ——> hydrated iron (III) oxide
This is ionisation.

Question 6

Aluminium corrodes partially, explain why.

Answer 6

The aluminium oxide (<- the oxide coating) that forms when being corroded doesn’t flake away, it forms a nice protective layer that sticks firmly to the aluminium below and stops any further reaction from taking place.

Question 7

Iron can fully corrode, explain why.

Answer 7

The rust that forms when iron is exposed to both oxygen and water is soft and crumbly and will flake off to leave iron available to rust again until it is all gone.

Question 8

What is the experiment that shows that both oxygen and water are needed for iron to rust?

Answer 8

Use three test tubes with an iron nail inside and a bung on top.

Question 9

What is the test that allows us to see that water alone is not enough for iron to rust.

Answer 9

Place an iron nail in a boiling tube with only boiled water (to remove any oxygen) and oil on top (stops any oxygen from reacting with the water and affecting the result) , the nail wont rust

Question 10

What is the test that allows us to see that only oxygen can’t corrode iron?

Answer 10

Put some calcium chloride into a boiling tube with the iron nail which will absorb any water from the air so it wont corrode the nail, the nail wont rust.

Question 11

How do you prove that it is only both oxygen and water that can make iron corrode?

Answer 11

Place the iron nail in water and leave a Half of the nail out in the air with a bung on top, the nail with corrode

Question 12

Why will the mass of the rusty iron increase?

Answer 12

The iron atoms in the nail have now bonded to the oxygen and water molecules which results in a compound that is heavier than the iron alone.

Question 13

What are the two ways to prevent iron from rusting? And what is the one that involves both?

Answer 13

1) barrier method (keep out oxygen and water)
2)sacrificial method
3)galvanising

Question 14

What are the three ways of using a barrier method to prevent iron from rusting?

Answer 14

1) painting/coating - ideal for both big and small structures and can be decorative.
2 electroplating - uses electrolysis to reduce metal ions onto an iron electrode. It can be coat the iron with a layer of another metal that wont be corroded away.
3) Oiling / Greasing - this has to be used when moving parts are involved, e.g bike chains.

Question 15

What is a sacrificial method?

Answer 15

Placing a more reactive metal, such as zinc or magnesium, with the iron. The water and the oxygen will react with the other metal rather than the iron.

Question 16

What is galvanising?

Answer 16

An object can be galvanised by coating it with a layer of zinc. The zinc layer is firstly protective, but if it is scratched the zinc works as a sacrificial method.

Question 17

What is an example of galvanising in the real world

Answer 17

Steel bars on the hull of a ship. These have to be replaced every couple of years but they do use a galvanising technique.

Question 18

What is the most common glass we use and how is it made?

Answer 18

Soda lime glass
made by heating a mixture of sand, sodium carbonate and limestone.

Question 19

What is Borosilicate glass made form?

Answer 19

sand and boron trioxide

Question 20

Is borosilicate glass harder or easier to melt than lime glass

Answer 20

Harder, it melts at higher temperatures

Question 21

What are some examples of clay ceramics?

Answer 21

Bricks and pottery

Question 22

How do you make a clay ceramic?

Answer 22

Shaping wet clay and heating in a furnace.

Question 23

How are most composites formed and why are they useful?

Answer 23

By combining two materials together. We have the reinforcements (fibres or fragments) of one material , this is then surrounded by a matrix or binder material

Question 24

What is the key purpose of composites?

Answer 24

Contain the different properties of materials

Question 25

What are two examples of composites?

Answer 25

1. Carbon fibre composite - reinforcement = carbon fibres , matrix = plastic resin
   Very strong and light which is good for cars or aircraft parts
2. Reinforced concrete - reinforcement = steel bars , matrix = concrete
   Very strong and used to make buildings

Question 26

How is a polymer formed?

Answer 26

By joining together lots of monomers

Question 27

1.What does an Ethene monomer look like?
2. What does an ethene polymer look like?

Answer 27

1. Two carbons double bonded together with two hydrogen atoms single bonded to each carbon
2. No. 1 but all joined together and there are no double bonds.

Question 28

What changes the properties of a polymer when using the same monomers?

Answer 28

The conditions they are made in.
1. Reaction temperature
2. Reaction pressure
3. Reaction Pressure or the catalyst

Question 29

What are the properties of thermosoftening polymers?

Answer 29

• melt when heated
• reshape when soft
• go back to a solid once cool

Question 30

Describe the process of melting and cooling a thermosoftening polymer

Answer 30

If we heat the polymer, the intermolecular forces brake, now the polymer strands can separate from each other and the polymer melts. If we cool the polymer , we reform the intermolecular forces and the polymer goes back to a solid.

Question 31

What is the property of thermosetting polymers and why?

Answer 31

They do not melt when heated this is because there are strong cross links between the polymer strands and they don’t melt by heat.