C15 - Using our resources (Part 1 - Corrosion, Alloys, Ceramics and Composites, Polymers)

Question 1

What is corrosion

Answer 1

Corrosion is the destruction of materials by chemical reactions with substances in the environment

Question 2

What is rusting

Answer 2

A corrosion process where ONLY iron or steel reacts with BOTH water and oxygen

Question 3

How to set up the rusting experiment

Answer 3

• Set up 3 test tube
• First test tube with distilled water open to air
• Second with boiled water (removes O2) with a layer of oil over it
• Third with anhydrous calcium chloride (removes water) and a bung to stop water vapour entering

Question 4

Methods to prevent corrosion

Answer 4

• Paint
• Oil/grease
• Electroplating w/ aluminium which forms aluminium oxide

Question 5

What is galvanising and what does it do

Answer 5

• Coating a metal with zinc
• Zinc is more reactive so corrodes instead through SACRIFICIAL PROTECTION
• Acts as a barrier against water and oxygen

Question 6

What is sacrificial protection

Answer 6

A more reactive metal than steel or iron placed over it so it oxidises before the steel/iron and prevents it from rusting

Question 7

What is an alloy

Answer 7

A metal that have small amounts of another metal or carbon added

Question 8

What is bronze an alloy of and what are its uses

Answer 8

• Mixture of copper and tin
• Used to make statues and bells

Question 9

What is brass an alloy of and what are its uses

Answer 9

• Mixture of copper and zinc
• Used to make musical instruments and door handles

Question 10

Properties and uses of aluminium alloys

Answer 10

• Low density but strong
• Can be used for aeroplanes and armour plating
• Also used for OVERHEAD CABLES

Question 11

What metals are in gold alloys and what are they used for

Answer 11

• Gold is alloyed with silver, copper and zinc
• Used for jewelery

Question 12

What is used to measure the proportion of gold in an alloy

Answer 12

Carats e.g. pure gold is 24 carats

Question 13

Properties and uses of low carbon steel

Answer 13

• Soft + easily shaped
• Used to make car bodies

Question 14

Properties and uses of high carbon steel

Answer 14

• Strong but brittle
• Used in construction and cutting tools

Question 15

What is stainless steel an alloy of and what are its properties and uses

Answer 15

• Iron alloyed with chromium and nickel
• Hard and resistant to corrosion
• Used for cutlery

Question 16

What is soda lime glass used for and how is it made

Answer 16

• Made by mixing sand, sodium carbonate and limestone(calcium carbonate)
• This is then heated in a furnance
• It cools into any intended shape
• Used for windows, wine glasses etc.

Question 17

How is borosilicate glass made

Answer 17

• Made by melting a mixture of sand and boron trioxide

Question 18

Properties and uses of borosilicate glass

Answer 18

• High melting point
• Used in kitchenware and labware

Question 19

How are clay ceramics made

Answer 19

• Clay found in ground
• Clay is wettened and shaped
• It is put in a high temp. furnace and heated

Question 20

How are composites made

Answer 20

• You get a reinforcement which is small fibres or fragments of a material
• The reinforcement is surrounded by a maxtrix or binder material
• This means composites have different properties that the materials in them

Question 21

Examples of composites

Answer 21

• Carbon fibre - strong and light
• Reinforced concrete
• Plywood + MDF
• Fibreglass

Question 22

What does the properties of a polymer depend on

Answer 22

• The monomers they are made from
• The conditions used to make the polymer

Question 23

Things to change in order to change the properties of the polymer

Answer 23

• Reaction temperature
• Reaction pressure
• Catalyst

Question 24

What happens when you heat and cool a thermosoftening polymer

Answer 24

• They melt allowing reshaping (+recycling)
• They go back to a solid when cooled

Question 25

Structure of a thermosoftening polymer

Answer 25

Randomely tangled polymer chains with weak intermolecular forces
These break under heat, melting the substance

Question 26

What happens when you heat a thermosetting polymer

Answer 26

They burn and this means they can’t be recycled or reshaped

Question 27

Structure of a thermosetting polymer

Answer 27

• Strong covalent bonds (cross links) between polymer chains
• Bonds just as strong as the ones between monomers
• This means only when the polymer breaks will the cross links break leading to burning