C1
- Created by: Jasmine2157
- Created on: 30-05-15 22:12
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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
- For
- 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
- Whether a substance will dissolve in a particular solvent depends on relative strengths of attractive forces
- 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
- Paint bahan
- 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.
- Deforestation
- 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
- Present day composition
- Esters + Perfumes
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