Extracion and uses of Metals

Question 1

where are most metals found?

Answer 1

• in ores
• and have to be separated
• metals that are unreactive don’t tend to form compounds with other elements. unreactive metals such as gold are found uncombined, so you have to find them and dig them up.

Question 2

what happens with metals that do react with other element to form compounds?

Answer 2

• most metals do react with other element to form compounds, which can be found naturally in the earth’s crust.
• if a compound contains enough of the metal to make it worthwhile extracting, the compound is called a metal ore.
• there are limited amounts of metal ores, they’re “finite resources”

Question 3

what happens the more reactive a metal is?

Answer 3

the harder it is to extract it from a compound

Question 4

what do lots of common metal oxides form?

Answer 4

• lots of common metals like iron and aluminium form metal oxides
• the metal can be separated from its oxide by a REDUCTION reaction
• the most common type of reduction reaction uses carbon as a reducing agent to separate the oxygen from the metal
• but carbon can’t be used for all metals.

Question 5

what are methods of extractions linked to?

Answer 5

• order of reactivity
• only metals that are LESS REACTIVE than carbon can be extracted by a reduction reaction with carbon, this is done by heating the ore with carbon monoxide. (e.g. iron oxide is reduced in a blast furnace to make iron)
• this is because more reactive elements form compounds more readily. carbon is more reactive than iron, so carbon “steals” oxygen from iron oxide
• in other words, carbon can only take the oxygen away from metals which are LESS REACTIVE THAN THE CARBON ITSELF

Question 6

what do very reactive metals form?

Answer 6

• very reactive metals form very stable ores
• i.e. its difficult to get the metal out of its compound
• so metals that are more reactive than carbon (higher in the reactivity series) have to be extracted using electrolysis
• electrolysis uses electricity to separate the metal from the other elements in the compound.
• for example, aluminium is extracted from aluminium oxide using electrolysis.

Question 7

what similarities do aluminium, iron and copper have?

Answer 7

• they are dense and shiny and have high melting points
• they have high tensile strength (strong and hard to break)
• they can also be hammered into a different shape (malleable)
• they are good conductors of electricity and heat energy

Question 8

what are the properties of iron and therefore what are its uses?

Answer 8

• iron has all the properties you’d expect of a metal. adding other materials can change its properties though
• wrought iron is almost completely pure iron.
• its malleable, so its used to make gates and railings
• the main problem is that it corrodes easily/rusts.
• alloys of iron called steels are often used instead of pure iron. steels are made by adding small amounts of carbon and sometimes other metals to iron.

Question 9

what are the properties of aluminium and therefore what are its uses?

Answer 9

• aluminium is also a typical metal. however, unlike iron it doesn’t corrode easily
• aluminium reacts very quickly with oxygen in the air to form aluminium oxide. a nice protective layer of aluminium oxide sticks firmly to the aluminium below and stops any further reaction taking place
• because aluminium doesn’t corrode its useful for products that come in contact with water e.g. drinks cans
• aluminium is also much less dense than iron, which makes it lighter
• this makes it useful when the weight of the metal is important, e.g. bicycle frame and aeroplanes

Question 10

what are the properties of copper and therefore what are its uses?

Answer 10

• copper is an especially good conductor of heat and electricity
• its used in electrical components and wiring as it has low resistance and so is efficient at transferring energy.
• its also used in heating systems, such as underfloor heating, as it allows speedy transfer of heat to the surroundings.

Question 11

why and how are alloys used?

Answer 11

• pure metals don’t always have the properties needed
• the regular structure of pure metals makes them soft, often too soft for use in everyday life
• alloys are made by adding other elements to the metal (usually other metals and/or carbon)
• different elements have different sized atoms. so when another element is mixed with a pure metal, the new atoms will distort the layers of metal atoms, making it difficult for them to slide over each other. this makes alloys HARDER than pure metals.
• alloys of iron called steels are often used instead of pure iron. steels are made by adding small amounts of carbon and sometimes other metals to iron.
• many other alloys are used in everyday life, e.g. brass (copper and zinc) and bronze (copper and tin)

Question 12

why are alloys harder than pure metals?

Answer 12

• different elements have different sized atoms.
• so when another element is mixed with a pure metal, the new atoms will distort the layers of metal atoms, making it difficult for them to slide over each other.
• this makes alloys HARDER than pure metals.

Question 13

what are the properties and uses of each type of steel?

Answer 13

1. LOW CARBON STEEL:
   - easily shaped
   - car bodies
2. HIGH CARBON STEEL:
   - very strong, inflexible, brittle
   - bridges
3. STAINLESS STEEL
   - corrosion resistant, hard
   - cutlery