topic 9

• alkanes

  • CnH2n+2
  • do not have double bond
• alkanes

  • CnH2n+2
  • do not have double bond
  • saturated
• alkenes

  • CnH2n
  • have carbon double bond
  • unsaturated
• isomer

  • isomers have the same molecular formula but different arrangement of atoms

  A) but-1-ene

  B) but-2-ene

  
• testing for alkenes and alkanes

  • bromine water tests for double bonds
  • alkenes turns colourless in bromine water
  • alkanes stays brown in bromine water
• addition reaction

  • a reaction in which reactants combine to form one larger product molecule and no other products
• naming products of addition reactions

  • carbon number added to , carbon number added to total number added prefix
  • prefix of element added
• alcohols

  • CnH2n+1OH
  • differs by CH2
  • alcohols are alkenes which have been oxididised
• chemical properties of alcohols

  • combusts completely to produce carbon dioxide and water
  • can be oxidised to form a carboxylic acid
  • react with reactive metals to form hydrogen as one of the products
• use of alcohols

  • varnish
  • renewable fuel
  • cosmetic solvent
  • antiseptic
• alcohol fermentation

  • fermentation of glucose -> produces ethanol + carbon dioxide
  • balanced equation C6H12O6 -> 2C2H5OH + 2CO2
  • conditions : yeast catalyst , anaerobic respiration , warmth , sugar dissolved in water
• advantages of production ethanol by fermentation

  • raw materials can be grown if land and climate is favourable
  • fractional distillation can be done to increase the ethanol content of the product
• disadvantages of producing ethanol by fermentation

  • product is impure
  • product only has 15% ethanol
  • slow process
• carboxylic acids

  • -COOH
  • CnH2n+1COOH
  • ends with -anoic acid
  • formed when alcohol is oxidised
  • example of oxidisation reaction ( gains oxygen )
• properties of carboxylic acid

  • turns blue litmus paper , red and universal indicator red
  • reacts with some metals to make -anoate salt and hydrogen
  • reacts with some bases to make -anoate salt and water
  • reacts with carbonates to form salts called -anoates and carbon dioxide and water
• carboxylic acid reaction with metal carbonate

  • effervescence / fizzing / bubbling of gas
  • solid disappearing over time
  • lime water goes cloudy
• production of ethanoic acid

  • ethanol is oxidised with oxygen in air
• Polymer : large molecules made from lots if monomers joined together

  synthetic polymers : a polymer manufactured in a lab or factory
• addition polymerisation : a type of polymerisation in which the monomers add on to each other and no small molecules are eliminated
• properties of polymers

  • poly(ethene) - flexible , cheap , good insulator
  • poly(propene) - flexible , shatterproof , high softening point
  • poly(chloroethene) / PVC - tough , cheap , long-lasting , good insulator
  • poly(tetrafluoroethene) / PTFE / Teflon -tough , slippery , resistant to corrosion , good insulator
• uses of polymers

  • poly(ethene) - plastic bags , plastic bottles , cling film , insulation of wires
  • poly(propene) - buckets and bowls
  • poly(chloroethene) / PVC - window frames , gutters , pipes ,insulation for electrical wires
  • poly(tetrafluoroethene) / PTFE / Teflon - non-stick coating for pans , bearings , containers for corrosive substance , stain proof carpets , insulation for electrical wires
• condensation polymerisation : a type of polymerisation in which the monomers join together and eliminate a small molecule such as water
• esters

  • alcohol + carboxylic acid -> ester + water
  • diol + dicarboxylic acid -> polyester + water
• naming ester

  • alcohol becomes first half of ester name
  • carboxylic acid becomes second half of ester name
  • eg , ethanol + methanoic acid -> ethyl methanoate
• disposal of plastics - recycling

  • advantage - saving finite resource , no need to use more of finite resource
  • disadvantage -not done effectively , long process , expensive -> cost of collection , processing
• disposal of plastics - incineration

  • advantages : gets rid of physical waste , energy produced
  • disadvantage : produces green house gases when burnt
• disposal of plastics - burying

  • adv - easy solution
  • disadv - chemical - microplastic leeching into soil , does not break down , take up landfill space
• nanoparticles

  • small particles of materials that have different properties to the bulk substance
• size of nanoparticles

  • very tiny
  • between 1-100 nm - bigger than an atom but not extremely big
  • contains few 100 atoms
• properties of nanoparticles

  • have small size
  • has extremely high surface area to volume ratio
  • more reactive
• Nanoparticles are used as a really good catalyst due to their high surface area.
• Nanoparticles of titanium dioxide are used in sunscreen, blocking UV rays from the sun.
• Metal nanoparticles, such as nanotubes, are used in electrical equipment for their ability to conduct electricity, creating mini electrical circuits for computer components.
• Hollow spheres of fullerenes with drugs are used in medical applications, diffusing out of the sphere, providing long term dosage.
• Silver nanoparticles are used in antimicrobial applications, such as wound dressings, surgical masks, and help stop the spread of deadly diseases.
• Iron nanoparticles are used to treat cancer, injected into tumours, heated using magnets, and destroy tumour without chemotherapy.