C1

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  • C1
    • Esters + Perfumes
      • Alcohol + organic acid  --> ester + water
      • Volatility: ease of liquid evaporating
        • Because there are only weak attractive forces between particles in substance, which are overcome easily, so particles with enough energy can escape from liquid
      • Organic acid: acid based on carbon
      • Perfume properties
        • Easily evaporates so perfume particles can easily reach the nose
        • Non-toxic so it doesn’t poison you
        • Doesn’t react with water as so it doesn't react with perspiration
        • Doesn’t irritate skin: prevents you suffering rashes
        • Insoluble in water so it can’t be washed off easily
      • Testing chemicals on animals
        • For
          • Chemicals don't have to be tested on humans
          • We know the chemicals aren’t toxic and don’t cause irritation
        • Against
          • Animal suffering
          • Animals may not react in the same way as humans
          • It’s now possible to carry out tests on cell cultures, though it’s more expensive
        • EU has now banned testing cosmetics on animals
      • Esters as solvents
        • Whether a substance will dissolve in a particular solvent depends on relative strengths of attractive forces
          • Between solute particles
          • Between solvent particles
          • Between solute + solvent particles
        • There are dif-ferent forces of attraction between water molecules compared to nail varnish particles; forces between water/nail varnish particles: stronger than any that can form between water + nail varnish. So, as forces can’t form between them, nail varnish is insoluble in water
    • Paints + Pigments
      • Paint bahan
        • Pigment: gives paint colour
        • Binding medium (liquid poly-mer): hardens to form con-tinuous layer when paint dries
        • Solvent: dissolves binding medium + makes paint more fluid
      • Emulsion paint: water-based, solvent is water, dries when water evaporates
      • Oil paint: pigments are dispersed in oil (may itself be dissolved in solvent)
        • Solvent evaporates when paint dries, leaving pigment + oil behind
        • Oil oxidises to form hard film as it reacts with oxygen in air
      • Paints: Type of mixture called colloid
        • Particles of 1 substance are mixed + dispersed with particles of another substance, but aren't dissolved in it
        • Components don't separate out as their particles are small enough not to settle at bottom
      • Pigmen Termokromik
        • Suhu sensitif: colour (cool), colourless (hot)
        • Useful to in-dicate if drink in cup penas or if water in ketel penas
      • Pigmen Phosphor-escent
        • Glow in dark: they can absorb light + store it; stored energy is released as light energy over a period of time
        • Useful for watching faces that glow in dark; may be used in fire safety signs placed near fire extinguishers: if fire occurs, lokasi of fire extinguisher can be seen even if lights fail
      • How paints dry
        • Paints are put on as thin layer which dries when paint's solvent evaporates
        • Emulsion paints; water evaporates leaving binder + pigment on surface
        • Oil paints: solvent evaporates, oil binder reacts with O2 in air; cross-linking bridges form between oil molecules + they polymer-ise, forming hard glossy finish
    • Problems With Plastics
      • Not biodegrade-able
      • Can be recycled, but there're many types of plastic + all have to be sorted (mahal)
      • Can be put into landfill, but destroys habitats
      • Can burn to provide energy, but many give off toxic gases
      • So new polymers are developing
        • That are biodegrade-able + can be decayed by bacteria
        • Polymers that dissolve are often made of starch
    • Atmosphere
      • Present day composition
        • 78% N (because it's so un-reactive)
        • 21% O
        • 0.035% CO2
      • Carbon Cycle
        • Shows how CO2 is controlled
        • Respiration: C6H12O6 + 6O2 --> 6CO2 + 6H2O (+ Energy)
        • Photosynth-esis: 6CO2 + 6H2O --> C6H12O6 + 6O2
        • Combustion: fuel + O --> CO2 + H2O
        • Affected by humans
          • Deforestation
            • Less photo-synthesis, so CO2 levels increase
            • Trees rot + burn after being cut + CO2 levels increase
          • Population increase
            • More fossil fuels burnt for energy, more cars, more industry etc.
      • Evolution theory
        • 1) After Earth formed, volcanoes released gases from Earth interior (degassing), to produce CO2 + H2O vapour rich atmosphere
        • 2) Some H2O vapour condensed to form seas + oceans
        • 3) CO2 began to decrease in atmosphere as it dissolved in oceans
        • 4) Primitive plants developed + started to photosynth-esise
        • 5) Due to photosynth-esis, O2 levels increased + CO2 decreased
        • 6) N gas formed due to chemical reactions + actions of soil bacteria

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