C3

C3

1. Metals

   • Metallic model showing metallic bonding
     • Lattice of positive ions surrounded by a 'sea' of freely moving electrons'
       • <---
   • Properties
     • High MPT & BPT - due to strong forces of attraction. Flexible & malleable - atoms arranged in layers that can slide over each other
     • Strong & conduct electricity (strong forces of attraction between ions and freely moving electrons to carry charge)
   • Uses of metals
     • Conductors/wires/power lines as conduct electricity
     • Metal cans - malleable (can be bent)
     • Submarines/aeroplanes - strong, can withstand pressure

2. How are metals with different reactivities extracted?

   • Reactivity series
     • Potassium Sodium Calcium Magnesium Aluminium
       • Extracted by electrolysis of molten ores
         • Very Expensive - lots of energy required to melter and produce required current
         • Eg. Aluminium extracted from ore bauxite - containing Al2O3 - by electrolysis
           • Al2O3 has very high MPT so is mixed with cryolite to lower MPT
             • Molten mixture contains free ions - so will conduct electricity
               • Positive Al3+ ions are attracted to negative cathode where they each pick up 3e- = neutral aluminium atoms which sink to bottom of electrolysis tank
                 • Negative O2- ions attracted to positive anode where they each lose 2e-
                   • Al3+ + 3e- -> Al
                   • 2O2- -> O2 + 4e-
                   • Aluminium oxide -> aluminium + oxygen
     • Zinc Iron Tin Lead (Hydrogen) Copper
       • Reduction of ores using carbon
         • Some metals can be extracted from their ores chemically by reduction using carbon. In this reaction, the ore is reduced as O2 is removed from it, and carbon gains oxygen so is oxidised
           • Carbon can only take the oxygen away from metals which are less reactive than C itself
             • C used as a reducing agent to remove O2 - no C left behind = pure metal
     • Silver Gold Platinum
       • Metals occur uncombined
         • These few metals are so unreactive that they are found in the earth as the metal itself
     • (Carbon)
   • Redox
     • ReductionIs Loss = lose e- to become +
       • OIL
     • Oxidation Is Gain = gain e- to become -
       • RIG
   • Greener methods for extracting metals
     • Bioleaching
       • Uses bacteria present in old soil heaps to oxidise sulphide minerals. soil heaps can be sprayed with sulphuric acid to make conditions acidic -> enzymes can work optimally. The run off from heaps = carefully collected (CuSO4) copper extracted in displacement reaction with iron / by electrolysis
     • Phytoextraction
       • Uses plants to take metal ions from soils / mining waste. Not yet used to extract metals that are useful, but very useful for taking toxic metals out of soil to 'clean up' environment around old mines
   • Displacement
     • More reactive metal displaces less reactive metal = new compound + displaced metal
       • Eg. Iron + Copper Sulphate -> Iron Sulphate + Copper
         • Iron loses 2e- to become 2+ ion ... it is oxidised
         • Copper gains 2e- to become e- ion ... it is reduced
   • Electrolysis of Molten Salts
     • Eg. Zinc Chloride
       • as it is heated, zinc chloride melts (was solid = no free moving electrons = no electricity conducted)
         • as soon as melted, compound begins to decompose chemically - bubbling at anode -> gas made = chlorine
           • shiny pieces of Zinc metal can be seen when current is switched off & when it is cool enough
             • Electric current splits compound into separate Zn + Cl elements
               • ZnCl2 -> Zn + Cl2
   • Electrolysis of aqueous solutions
     • Ionic Salt = ions mixed with water molecules. Eg. NaCl = Na+ + Cl- + water molecules
       • Na is more reactive than hydrogen so H gas is produced at Cathode
         • Chlorine ions present in solution so chlorine gas produces at Anode
           • Na+ reacts with OH- to form NaOH solution

3. Crude Oil

   • What is it?
     • Thick, sticky, dark-coloured liquid from the remains of tiny plants and animals called plankton.Pumped out of Earth's crust/from wells underground/sea
     • Mixture of hydrocarbons (hydrogen and carbon atoms only). Compound that is very important in human life - fuel, diesel, petrol, central heating, bottled gas, roads, roofing, lubricants, etc.
   • How do you separate it?
     • Fractional Distilation
       • Mixture- different hydrocarbon chain lengths = different BPTs
         • Longer chains = more energy needed to break them as they have more bonds to break, intermolecular bonds are stronger = higher MPT & BPT
       • Crude oil heated in column, evaporates and condenses @ certain levels (=certain temps) , longer chains = higher BPT
       • As they travel higher up the column temp decreases, hydrocarbons reach their BPT and condense into separating levels
   • Homologous series
     • Alkanes
       • Methan, Ethane, Propane, Butane, Pentane, Hexane, etc.
       • Meth-1, Eth=2, Pro=3, But=4, Pent=5, Hex=6, etc.
         • (Amount of Carbon atoms)
       • Formula=CnH2n+2
       • Cracking alkanes
         • Alkane + heat + catalyst = smaller alkane + alkene
           • Useful as smaller hydrocarbons have more uses and have the biggest demand
       • Lower MPT & BPT, flammable, burn more easily, evaporate easier, useful as fuels, not very reactive
     • Alkenes
       • Formula = CnH2n
       • Contain C=C bond -> very reactive
         • NO METHENE
       • high MPT & BPT, become less flammable as C atoms increase, larger molecules = stronger intermolecular forces
         • Still very flammable, burn in combustion
     • Alcohols
       • Functional group = OH
       • Methanol, Ethanol, Propanol, Butanol, ...
       • Not very reactive, only in combustion, liquid @ room temp
     • Carboxylic acids
       • Functional group = COOH
       • low pH, react with metals & carbonates and make salts, less toxic, less reactive and less corrosive than the acids usually used in school labs
       • usually found in foods & cosmetic products
       • Methanoic, Ethnic, Propanoic, Butanoic, ... (acid)