Chemistry unit 2 (materials)

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What Are the 5 main sources of raw materials?
Earth, living things, sea, air, crude oil
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What raw materials can be found in earth?
Lime (from limestone) salt (from rocksalt) aluminium (from bauxite) and iron (from haematite)
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What's the difference between natural materials and synthetic materials?
Natural materials are derived directly from raw materials eg cotton, wool, silk where as synthetic materials are man made and They are put through a manufacturing processes eg glass, PVC, polythene
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What is a nanometre?
A nanometre (nm) is a unit of length (10-9m)
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Nanoscience uses particles with sizes in the range... Because...
1-100nm because it gives them a very large surface area which gives them different properties to traditional materials
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Uses on nanotechnology...
Sun cream, silver nanopartickes in wound dressings and soaps,carbon nanotubes to strengthen materials
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Risks of nanotechnology...
The effects are relatively unknown, could catalyse reactions in the body, if breathed in causes irritation to the lungs
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How are metals low in the reactivity series extracted?
Reduction with Carbon or carbon monoxide
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How are metals which are high in the reactivity series extracted?
Metals above aluminium are extracted by electrolysis
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What is electrolysis?
Electrolysis is the decomposition of a liquid electrolyte using a direct current of electricity
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The electrodes have a positive and negative...
Positive is called the cathode, negative is called the anode
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All electrolytes conduct electricity because...
They have free ions that can move and carry charge
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Where do the positive and negative ions go during electrolysis?
The positive cations move to the negative cathode where they gain electrons to become atoms. The negative anions move to the positive anode where they lose electrons to become atoms
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What's the difference between oxidation and reduction?
Reduction is the gain of electrons and it happens at the cathode. Oxidation is the loss of electrons and it happens at the anode.
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What is aluminium ore called?
Bauxite
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Extraction of aluminium from its ore...
Bauxite us purified to form alumina which is dissolved in molten cryolite to reduce its melting point and increase conductivity, this is at a temperature of 900c. There are reactions at the cathode and the carbon anode.
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Why does the carbon have to be replaced periodically?
Because it wears away as it reacts with oxygen to form carbon dioxide
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The cost of extraction...
The cost of electricity and heat to keep molten alumina is very high so the cryolite and oxide crust reduces the cost. Recycled aluminium is also used as it saves resources and energy and costs less than new aluminium
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The solid material put into the blast furnace is called charge. What is this made up of?
Iron ore (haematite), limestone (calcium carbonate) and coke (carbon).
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Production of the reducing agent...
Coke burns in oxygen from hot air blasted in to produce carbon dioxide which reacts with more carbon to produce the reducing agent, carbon monoxide
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Reduction of iron ore to iron...
Iron (III) oxide reacts with carbon monoxide to produce molten iron and carbon dioxide. The iron loses oxygen in reduction and carbon monoxide gains oxygen in oxidation
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Removal of acidic impurities...
Calcium carbonate thermally decomposes to form calcium oxide and carbon dioxide. Silicon dioxide impurities reacts with calcium oxide to produce molten ****. The molten iron and **** sink to the bottom where they are tapped off seperately.
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Card 2

Front

What raw materials can be found in earth?

Back

Lime (from limestone) salt (from rocksalt) aluminium (from bauxite) and iron (from haematite)

Card 3

Front

What's the difference between natural materials and synthetic materials?

Back

Preview of the front of card 3

Card 4

Front

What is a nanometre?

Back

Preview of the front of card 4

Card 5

Front

Nanoscience uses particles with sizes in the range... Because...

Back

Preview of the front of card 5
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