Planet Earth
Composition of clean air: nitrogen (78%), oxygen (21%), argon (0.9%), other gases
(0.1%): carbon dioxide, water vapour, neon, noble gases
Uses of nitrogen: manufacturing of fertiliser in Haber process: N2 + H2  NH3, liquid
nitrogen is used to store embryos and living tissues, filling bags of crisps.
Uses of oxygen: production of steel from cast iron, oxygen cylinders is used to help the
breathing of sick people.
Uses of argon: used in light bulbs to prevent the tungsten filament from burning away.
Note: when you're asked for a use of oxygen, breathing is not considered to be a correct
answer because it is the air rather than oxygen that we breathe. Oxygen is just one fifth
of the air. You need to give a use of pure oxygen
Pollution of the air:
Methane: is a product of anaerobic decay of organic matter and is produced in large
quantities in rice paddy fields and landfill rubbish sites, it is also produced by the
digestive systems of animals  greenhouse effect
Carbon dioxide: is produced through respiration and burning  greenhouse effect
Sulphur dioxide: when coal is burnt, sulfphur combines with oxygen to produce SO2,
this
Nitrogen oxide: when air is burnt in furnace, nitrogen combines with oxygen to produce
NO2
acid rain wear away limestone buildings, statues, acidify lakes  kill fish
carbonmonoxide: incomplete combustion of hydrocarbon fuel produces CO, this is
highly toxic gas, it combines with haemoglobin in blood and stops it from carrying
oxygen. Catalytic converter is used to
green house effect: imagine a house made of glass, sunligh is easily get in through
transparent glass but is trapped by glass walls when it is reflected back  temperature
inside glass house increase
Why green house but not glass house  because glass house is used for growing trees
inside  the name green house stuck
When there is so much methane or CO2 in the atmotphere, it plays as a role of glass
ceiling, letting light pass through but trap heat when it is reflected
greenhouse effect  global warming (enhanced greenhouse effect)  climate change
glaciers and polar ice will melt  sea level rises
surface temperature of the Earth will increase
Water treament: removing solid particles and adding chlorine to remove bacteria from
water in rivers and lakes and underground water.
The nature of matter
Matter exists in 3 states:
- solid: has a fixed volume, high density, e.g. metal bar
- liquid: has a fixed volume, medium density, e.g. water
- gas: its volume is also container's volume, low density, e.g. oxygen
Kinetic theory of matter
Changes of state:
- melting: changes from solid  liquid, e.g. when ice is taken from refrigerator, it melts
to liquid
- freezing: changes from liquid  solid, e.g. when water is put inside freezer, it is frozen
to ice
- evaporation: changes from liquid  gas, e.g.
- condensation:
- sublimation: direct changes from solid  gas or gas  solid, e.g.
volatile liquid: evaporate easily and has a low boiling point
pure substance: e.g. distilled water (contain H2O)
impure substance, e.g. mineral water (contain H2O, other mineral, Ca, K, ..)
impurity makes a substance harder to melt  higher melting point
harder to freeze  lower freezing point
Diffusion
Brownian motion
Elements and compounds
Atom, molecule, element, compound, mixture
Seperating solid/liquid mixture: filtration, centrifuging, decanting, evaporation,
crystallation, distillation
Seperating liquid/liquid mixture: seperating funnel, fractional distillation
Seperating solid/solid mixture: chromatography
Chemical reactions
Acids, bases and salts
Quantitative chemistry
Ar: relative atomic mass (refer to periodic table of elements) Mg = 24  1 mol Mg
weighs 24g
Mr: relative molecular mass NaCl = 23 + 35 = 58  1 mol NaCl weighs 58g
1 mole of gas occupies 24dm3(l) at room temperature pressure (rtp)
Concentration of solution = mole/volume
Empirical formula: simplest ratio of atoms (C2H4  CH2)
Percentage yield = (actual yield/theoretical yield) x 100%
Percentage purity = (mass of pure substance/mass of impure substance) x 100%
How far? How fast
Patterns and properties of metals
Industrial inorganic chemistry
Organic chemistry
Petrochemicals and polymers
Chemical analysis and investigation