iGCSE Chemistry Section E

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Methods of extraction from the ore

potassium
sodium
lithium                              electrolysis of the molten chloride or molten oxide
calcium
magnesium
aluminium
carbon
zinc
iron                                 heat with reducing agent such as carbon or carbon monoxide
copper
silver                              occur naturally as the elements
gold

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Extraction of iron

(http://sciencepark.etacude.com/lzone/reactivity/furnace.jpg)

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Crude Oil

(http://www.bbc.co.uk/schools/gcsebitesize/science/images/5_fractional_distillation.gif)

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Cracking

Long chain hydrocarbons (alkane) molecules are passed over a catalyst and heated to about 600-700°C. They break down into short-chain alkane molecules and atleast one alkene. There is usually more than one possible different combination of things it breaks up into.

E.g.    C10H22(g)-->C8H18(g) + C2H4(g)
    OR C10H22(g)-->C7H16(g) + C3H6(g)
    OR C10H22(g)-->C7H14(g) + C3H6(g) + H2

 

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Addition polymers

Breaking a monomer's carbon=carbon bond and allowing the monomers to join together to form a long chain of carbon atoms all bonded together.

n CH2=CH2  -->  -(-CH2-CH2-)n-
 MONOMER    REPEATING UNIT

Uses of polyethene:
HDPE- milk jugs, garden furniture
MDPE- storage tanks for fuel
LDPE- plastic bags

Diposing of addition polymers
Landfill
Incineration
Recycling

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Condensation reactions

Two molecules react together to form a new, larger molecule with the elimination of a small molecule such as water.
Esterification: the reaction between an alcohol and a carboxylic acid.
Carboxylic acid: -COOH group
Amide: -NH2 group

  0                           0
  ||                           ||
-C-OH    H-O-  --> -C-O- + H2O
water eliminated    ester

A typical polyester: terylene
A typical polymide: nylon

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The Haber Process - Manufacturing ammonia

3H2(g) + N2(g) <-> 2NH3(g)        H = -92kJ/mol
Uses of ammonia:
Fertilisers
Nitric acid
Nylon

(http://johnvagabondscience.files.wordpress.com/2008/11/nh3.jpg)

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The Contact Process - Manufacture of sulfuric acid

Stage 1: S + O2 --> SO2
                  Making sulfur dioxide
Stage 2: 2SO2
(g) + O2(g) <-> 2SO3(g)
                 Making sulfur trioxide
Stage 3: H2SO4(l) + 2SO3(g) --> H2S2O
Paints
      
           

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Contact process flow chart

(http://wikieducator.org/images/thumb/a/a8/Contact1.jpg/500px-Contact1.jpg)

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The manufacture of sodium hydroxide and chlorine

Anode: 2Cl-(aq) --> Cl2(g) + 2e-
Cathode: 2H2O(l) + 2e- --> 2OH-(aq) + H2(g)
Overall equation: 2NaCl(aq) + 2H2O(l) --> 2NaOH(aq) + H2(g) + Cl2(g)
(http://www.chemguide.co.uk/inorganic/group7/membrane.gif)

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