Using Resources
Cards (87)
- Corrosion happens when metals react with oxygen and water (vapour) in the air to form a metal oxide
- Rusting is the corrosion of iron and steel
- Rust = hydrated iron (III) oxide
- Iron +oxygen + water —> hydrated iron (III) oxide
- Aluminium corrodes but once aluminium oxide forms it acts as a protective layer as it doesn't flake off meaning no more aluminium is exposed to corrosion
- Hydrated iron oxide is prone to flaking so when ti comes off new iron is exposed and at risk of rusting
- An iron nail in a boiling tube with boiled water and a layer of oil will not rust as there is no oxygen
- An iron nail in a boil tube with calcium chloride will not rust as there is no water vapour
- An iron nail in boiling tube with salt water will rust very quickly as the salt acts as a catalyst
- Painting stops rust ais acts as a barrier between the air and the protected object
- Painting objects to prevent rust is low cost, and means less repairs are needed on vehicles
- Painting objects to prevent rusting means the object needs frequent paint touch ups
- Oiling or greasing to prevent rusting is done on moving mechanics
- Oiling or greasing to prevent rusting means long maintenance intervals and reduced friction
- Oiling or greasing to prevent rusting means the object is flammable and may attract bugs
- Galvanising to prevent rust is the coating of zinc on an iron object to act as barrier
- Galvanising to prevent rust means the object is reliable and has a long life
- Galvanising to prevent rust is expensive and can be toxic
- Electroplating is the use of electrolysis to put a thin layer of metal on an objects
- Anode - plating metal
- Electrolyte - contains ions of the plating metal
- Sacrificial protection to prevent rusting is coating a metal object in a more reactive metal coating meaning the more reactive metal will oxidise quicker
- an example of sacrificial protection is commonly when iron is coated in zinc
- An alloy is a mixture of a metal and at least one other element
- Alloys make metals stronger than they are in their pure form
- Low carbon steel is easily shaped, sued to make car bodies (0.1 -0.3% carbon)
- High carbon steel is very hard, inflexible, used to make bladed tools and bridges (0.22 - 2.5% carbon)
- Stainless steel is corrosion resistant, used to make cutlery and containers for corrosive substances
- Chromium + iron = stainless steel
- Bronze is harder than copper, used to make medals, decorative ornaments and statues
- Copper +tin = bronze
- Brass is more malleable than copper, used when low friction is needed, used on taps and door fittings
- Copper +zinc = brass
- 18 carat gold is harderend gold, used for jewellery and decoration
- Gold is usually alloyed with zinc, copper or silver
- Pure metals have their particles arranged in orderly patterns where they can easily slide over other but once another element is added it is much bigger so makes it difficult for the layers to slide over one another
- Ceramics are non-metal solids with high melting points that aren't made from carbon based compounds
- Clay is a ceramic which is soft and can then harder at high temperatures used to make bricks and pottery
- Glass is a ceramic which is generally transparent but can be moulded at high temperatures and brittle when thin
- Soda lime glass is made by heating sand, sodium carbonate and limestone