C20 - Making our resources (PAPER 2) Flashcards
What is corrosion
when a material reacts with substances in the environment and eventually wears away
What are the two ways corrosion can be prevented
- physical barriers
- sacrificial protection
How are physical barriers used to prevent corrosion
- the material is covered with a barrier such as grease or electroplated
- this outside layer will protect the material from corroding
How can aluminium be used as a physical barrier to prevent corrosion
the layer of aluminium around the metal reacts with oxygen in the air to form aluminium oxide.
- This layer protects the rest of the material from corroding
What is electroplating
covering a material with a thin layer of metal
How is sacrificial protection used to prevent corrosion
- a more reactive substance is placed on the material. The more reactive substance will react with the environment instead of the main metal
What is the term used for applying sacrificial protection to a substance
galvanising
What is rusting
iron corroding by reacting with oxygen and water from the environment
What is the use of alloys
allows us to tailor the properties of metals to specific uses
What is the
- composition
- properties
- use
of bronze
- copper and tin
- resistant to corrosion
- statues, decorative items, ship propellers etc.
What is the
- composition
- properties
- use
of brass
- copper and zinc
- very hard but workable
- door fittings, taps, musical instruments
What is the
- composition
- properties
- use
of gold alloys
- gold with copper, silver and zinc
- attractive, corrosion resistant, hardness depends on carat
- jewelley
How is the proportion of gold in a gold alloy measured
- What is the term for 100% gold
- What is the term for 75% gold
- carats
- 24
- 18
What is the
- composition
- properties
- use
of high carbon steel
- iron with 1-2% carbon
- strong but brittle
- cutting tools, metal presses
What is the
- composition
- properties
- use
of low carbon steel
- iron with <1% carbon
- soft, easy to shape
- extensive use in manufacture of cars, machinery, ships, containers, structural steel
What is the
- composition
- properties
- use
of stainless steel
- iron with chromium and nickel
- resistant to corrosion, hard
- cutlery, plumbing
What is the
- composition
- properties
- use
of aluminium alloys
- many different alloys possible
- low density, properties depend on composition
- aircraft, military uses
What are ceramics
materials with versatile properties
How is soda-lime glass
- manufactured
- what are its properties
- what are its uses
- heating a mixture of sand, sodium carbonate, limestone
- transparent, brittle
- everyday glass objects
How is borosilicate glass
- manufactured
- what are its properties
- what are its uses
- heat sand and boron trioxide
- transparent, brittle, higher melting point than soda-lime glass
- oven glassware, laboratory glassware
How are clay ceramics (pottery + bricks)
- manufactured
- what are its properties
- what are its uses
- shape wet clay then heat it in a furnace
- hard, brittle, easy to shape before manufacture, resistant to corrosion
- crockery, construction, plumbing fixtures
What two factors do the properties of polymers depend on
- the monomers that make them up
- the conditions under which they are made
What does LDPE stand for
- how is it formed
- why does it have a low density
Low density poly(ethene)
- when the addition polymerisation reaction of ethene is carried out under high pressure and in the presence of a small amount of oxygen
- the branched polymer chains cannot pack together
What does HDPE stand for
- how is it formed
- why does it have a high density
High density poly(ethene)
- when the addition polymerisation reaction of ethene is carried out using a catalyst at 50*C
- polymer chains are straight and so they can pack tightly together
