C2
- Created by: Jasmine2157
- Created on: 31-05-15 10:39
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- C2
- Construction Materials
- Rocks
- Marble: Metamorphic, made from limestone under great heat & pressure over a long period of time
- Shiny, hard
- Usually found deep underground
- Granite: Igneous, molten rock which has cooled and solidified
- Chalk: Soft, powdery, white, found near Earth's surface
- Marble: Metamorphic, made from limestone under great heat & pressure over a long period of time
- Clay makes bricks
- Sand + limestone --> glass
- Limestone
- Thermal de-composition: breaking a substance down by heat into 2 or more substances
- CaCO3 --> CO2 + CaO
- CaO + H2O --> Ca(OH)2
- Ca(OH)2 + CO2 --> CaCO3 + H2O
- CaO + H2O --> Ca(OH)2
- Uses
- Building stone
- Toothpaste
- Bread
- Neutralising acid soil
- Glass
- Lime
- Cement
- Iron
- CaCO3 + H2SO4 --> CaSO4 + CO2 + H2O
- CaCO3 + 2HNO3 --> Ca(NO3)2 + CO2 + 2H2O
- Cement: powdered clay + powdered limestone - mixed & heated
- Limestone + iron ore --> iron
- Sand + cement + aggregate --> (water, chemical reaction) concrete
- Cement bonds agregate + sand; liquid concrete: then poured over steel bars or mesh to reinforce concrete
- Reinforced concrete: better construction material
- Has flexibility of steel, so doesn't break under tension
- Has hardness of concrete
- Can be imported in earthquake areas
- Reinforced concrete: better construction material
- Cement bonds agregate + sand; liquid concrete: then poured over steel bars or mesh to reinforce concrete
- Rocks
- Making Cars
- Rusting
- Only steel + Fe rust
- Fe: rust forms in tiny flakes + damp air can attack metal below
- In time, it rusts all the way through
- Fe + O + H2O --> Hydrated Fe (3) Oxide
- Al: thin coat of Al2O3 forms (tenacious), so protects it from oxygen
- Materials
- Al car body + hub caps
- Low density, malleable, doesn't corrode
- Cu electrical wiring
- Ductile, good electrical conductor
- Pb-acid battery
- Chemical reaction produces electricity
- Plastic dash-board, bumper
- Rigid shape, cheap, doesn't corrode
- Textile fibres in seats
- Can be woven + dyed, hard-wearing
- PVC Wire covering
- Electrical insulator, flexible
- Glass/plastic composite in windscreen
- Transparent, doesn't shatter
- Al car body + hub caps
- Al v. Steel
- Al2O3: impervious (won't let oxygen in to react with Al)
- Al2O3: tenacious (won't flake off Al)
- Al: lighter than Fe
- Mineral cryolite helps extract Al from ore
- Al: corrode less, lighter, more expens-ive than steel, better fuel economy, longer lifetime
- Recycling
- EU law will soon require 95% of car to be recyclable
- Makes sense because...
- Al, Fe + Cu ores are finite sources
- Saves energy + land needed for landfill + avoids environmental damage from mining
- Plastic: made from non-renewable crude oil
- Recycling batteries stops toxic materials entering environment
- Difficulties
- Expensive to sort all differ-enf materials
- Different alloys + metals
- Range of polymers (plastics) used
- Expensive to sort all differ-enf materials
- Rusting
- Superconduct-ors: materials that have no or little resistance
- Current: flow of electrons
- Only work at ~-200C; to be useful, they should work at 20C, room temperature
- Can be used in electricals
- Resistance stops currents from flowing in a circuit
- Metals have many free electrons, so currents can flow easily through them (low resist-ance)
- So they are good electrical conductors
- Insulators: opposite
- Benefits
- Fast electronic circuits
- More powerful electro-magnets
- Electricity can be transmitted through wires with no power loss
- Acids + Bases
- Indicators
- Contain dyes which change colour with pH
- Single indicators change colour suddenly at particular pH
- Different indicators change colour at different pH
- Universal indicator: mixture of dyes, changes colour grad-ually with pH
- All acids form H+ ions in water
- pH of acid depends on concentration of H+ ions
- Higher H+ ion concentra-tion: lower pH
- Alkali: soluble base
- Alkalis form OH- ions in water
- Equations
- Acid + base --> salt + H2O
- Acid + metal carbonate --> salt + H2O + CO2
- Key ionic equation for neutralisation: H+ + OH- --> H2O
- Acid + NH3 --> ammonium salt
- Neutralisa-tion: H+ ions react with OH- ions to make neutral water
- Indicators
- Fertilisers + Crop Yields
- % error: (error in apparatus / volume) * 100%
- % of N: (#atoms of N in compound * 14 / RFM of compound) * 100%
- Larger volume = lower % error
- Mass of reactants = mass of products
- Fertilisers
- HNO3 + NH3 --> NH4NO3
- 3H3PO4 + 9NH3 --> 3(NH4)3PO4
- H2SO4 + 2NH3 --> (NH4)2SO4
- HNO3 + KOH --> KNO3 (+ H2O)
- Advantage: increases crop yield
- Problem: eutrophication
- Making them in a lab
- Measuring cylinder to measure a particular volume of an alkali solution
- burette to add acid a little at a time
- Filter funnel to remove solid crystals of fertiliser from solution
- (Mass given / its Mr) * Mr of what you need to find
- Construction Materials
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